Synopsis of Neotropical Trogolaphysa Mills, 1938 (Collembola: Paronellidae) with Reduced Eye Number, and Description of Two New Troglobiontic Species from Belize †

: The genus Trogolaphysa comprises 81 described species distributed across the Neotropical and Afrotropical regions. In the Americas, just over half of the species found in subterranean habitats have a reduced eye number (0–5 eyes). Subterranean species are of interest as models to study the evolution of morphological adaptations. Many subterranean species of Trogolaphysa were described before the introduction of chaetotaxy as a diagnostic tool and thus remain incompletely described and diagnosed. To identify gaps in descriptions and facilitate the identification of newly collected forms, we provide standardized summary descriptions, species diagnoses, diagnostic tables, and a dichotomous key to the 33 Neotropical species of Trogolaphysa with reduced eye number. As a result of this synthesis, we describe two new troglobiontic species, Trogolaphysa reneaui n. sp. and Trogolaphysa welchi n. sp. from Belizean caves.


Introduction
Trogolaphysa Mills, 1938 is a medium size genus of Paronellidae (Hexapoda: Collembola) characterized by the presence of apically rounded or truncate scales covering the head, body, and ventral face of the furcula, three bothriotricha on the fourth abdominal segment, one or two rows of spines dorsally on the dens, and a relatively short mucro with three to five teeth.The genus is restricted to the Americas and Africa.The 81 described species are unevenly distributed between biogeographic regions, with 13 species restricted to Africa [1] and the remaining 68 found in the Neotropics [2,3].The African fauna is poorly known, and all described species are surface forms with color patterns and six to eight eyes.The Neotropical fauna is significantly more morphologically diverse.The 68 New World species are commonly found in leaf litter and subterranean habitats.Just over half of the Neotropical species (36) are restricted to subterranean habitats; most (30) are colorless or, if pigmented, lack a color pattern, and are either eyeless or have fewer than six eyes [2][3][4][5][6][7].
Subterranean Trogolaphysa are of general evolutionary interest because many species exhibit morphological adaptations to hypogean life [4].Contrary to Pseudosinella Shäffer, which has diversified mostly in temperate subterranean habitats ( [8] but see [9]), all troglophilic and troglobiontic Trogolaphysa are found in the tropics.This provides a system to potentially tease apart subterranean environments from latitudinal effects.
During a recent visit to caves in the Belize District, Belize, Central America, junior author JJW collected several specimens of colorless and eyeless springtails.This material Taxonomy 2024, 4 200 appeared to represent two new species in the genus Trogolaphysa.While comparing the new material to previously described species, it became clear that most subterranean forms with reduced eye number remain poorly and/or unevenly described.Few descriptions before the work by Mari Mutt [10] referred to chaetotaxy and the only characters of diagnostic utility consistently described were eye number, labial chaetotaxy, claw complex, and mucro.
To facilitate the comparison between described species and specimens from Belize, and to call attention to gaps in diagnostic character descriptions across species, we present summary descriptions, diagnostic tables, and a species-level identification key for all Neotropical species of Trogolaphysa with fewer than six eyes.We also describe two new troglobiontic species from Runaway Creek Nature Reserve in central Belize.

Study Area
Runaway Creek Nature Reserve (RCNR) is a 2428-hectare private reserve located on the east side of the Coastal Highway, approximately 16 km south by southeast of La Democracia, Belize, Central America (N 17.3185, W 88.4457).Vegetation is characterized as pine savanna in the lowlands and broadleaf forest in the karst hills [11,12].RCNR is nestled within the Sibun River and Northern and Southern Lagoon watersheds [13] and the key biodiversity area of the Peccary Hills [14], while the surrounding coastal plain is considered an important bird conservation area [15].All caves are in the karst hills.

Field Sampling
From 22 through 30 July 2019, four caves were sampled within the RCNR boundary.Arthropods were collected via direct intuitive searches within cave deep zones and opportunistically while traversing the length of each cave [16].Three observers spent four hours collecting arthropods within each cave.RCNR personnel and JJW searched for arthropods on flood detritus, mud floors, bat guano, other mammal scat, animal carcasses, and along the edges of pools.
During the sampling period, the region experienced a widespread drought.With the exceptions of several small subterranean pools, the caves were muddy but rapidly becoming desiccated.In subsequent site visits, JJW observed three of the four study caves as largely flooded from the entrance to the deep zone.

Analysis and Preparation
Specimens were cleared in Nesbitt's fluid and mounted using Marc André II fluid [17].Slides were studied with an Eclipse E400 phase/contrast Nikon microscope.Habitus photographs were produced with an Axiocam HRC camera attached to a Zeiss Discovery V-20 dissection microscope.Photographs were enhanced using Adobe Photoshop Elements (v.19).Original drawings were made using a Y-IDT drawing tube attached to the Nikon microscope.New line drawings and new renditions of previously published hind claws were inked using Microsoft Power Point (v.16).

Morphological Description Conventions
The traditional macrochaeta formula proposed by Gisin and others [18] displays the number of macrochaetae on the thorax and abdomen in the form of Th. 2, Th.3/Abd.1, Abd. 2, Abd. 3, Abd. 4 element C1 + Abd. 4 macrochaetae in column B. A modified version of this formula can also be used to describe the dorsal macrochaetae in Trogolaphysa and in all other Paronellini sensu [19].We propose two versions of the formula: (1) the long, or complete, formula with structure as follows: anterior head macrochaetae (rows A, M, S, Ps), posterior head macrochaetae (rows Pa and Pm)/Th. 2 (a5 and number of macrochaetae in the p3 complex), Th. 3/Abd.1, Abd. 2, Abd. 3, Abd. 4 inner macrochaetae (columns A and B, including B6), Abd. 4 outer macrochaetae (columns D, E, and F) + Abd. 4 meso-/microchaetae along posterior margin of segment; and (2) the short macrochaeta formula, which includes only the paired macrochaetae of the head, mesothorax, metathorax and Abd. 4, and Abd. 4 posterior margin chaetae.The short version of the formula is proposed because, for all neotropical Trogolaphysa in which the chaetotaxy is known, variation in macrochaetae number is limited to the paired macrochaetae of the head, thorax, and Abd. 4, whereas Abd.1-3 are invariably carrying zero, two (m3 and m5), and four (m3, am6, pm6, p6) macrochaetae, respectively.Thus, for Trogolaphysa welchi n. sp., the long and short formulae are 42/72/02435 + 13-14 and 32/72/35 + 13-14, respectively.The short formula is used in individual species diagnosis and in the diagnostic tables.
Nomenclature and homology of the chaetotaxy on Abd. 4 are according to [20].The homology of lateral elements on Abd. 4 in [3] differs from that in [20,21].Provided that homologies in [20,21] are based on evaluation of primary chaetae that agree in all relevant points, we report the macrochaeta of species described in [3] using the homologies accepted by [20,21].In any case, the chaetotaxy of the lateral section of Abd. 4 (external to column T) is complex.Multiple supplementary elements develop into macrochaetae in different species, especially near the postero-lateral margin of the segment.Homology of most postero-lateral supplementary elements is unclear; for that reason, we do not include them in the formula or description.Thus, we only report the condition of macrochaetae in columns D, E, and F. The only exception is element Te3, which in Trogolaphysa sotoadamesi Ferreira, Oliveira and Zeppelini, 2022 [3] is developed into a large macrochaeta.Macrochaetae with large sockets are short, thick, and blunt, whereas macrochaetae with small (relatively speaking) sockets are long, slender, and acuminate.In the descriptions below, macrochaetae with large sockets are represented by upper-case letters and macrochaetae with small sockets are represented by lower-case letters.
As the hind claw complex has been the most important character system for diagnosing Trogolaphysa species, we provide simplified renderings of the hind claw complex for all species with fewer than six eyes described before 2022.Drawings of the claw of the 11 species recently described in [3] are not reproduced, but these species are included in the identification key, diagnostic tables, summary descriptions, and abbreviated diagnosis.Differences in unguis inner teeth origin distribution, relative length, and shape are the main features described.Tooth origin distribution (Figure 1A) is calculated as the distance between the origin of the inner edge of the unguis and the tooth's origin, divided by the total length of the inner edge, multiplied by 100.The term "subequal" is used if the teeth are of similar size.Description of relative length of a tooth is qualitative and described as small (Figures 2I and 3A), well-developed or -marked (Figure 2A), or enlarged (Figure 2E).Basal teeth are referred to as symmetric when they are the same general shape and asymmetric when they differ in shape (e.g., T. maya Mills, 1938 [23] has asymmetric basal teeth, Figure 3B, as one tooth is acuminate and elongate, and the other is wedge-shaped).
Measurements from published drawings were standardized as follows: tenent hairs were measured from tip to the base of the chaeta itself, not including the socket; the unguiculus was measured from its origin on the tarsus to the most distal point (Figure 1A); the length of the inner edge of the unguis was linear and did not account for the curvature of its distal half; the insertion of the inner teeth was measured to the approximate middle of the curvature of the tooth's origin as shown in Figure 1A.The width of the mucro was measured at the origin of the basal tooth, while the mucronal length was measured from the tip to the midpoint of contact with the dens (Figure 1B).Mucrones with a length-towidth proportion smaller than 2.49 are described as paraquadrate, those with proportions between 2.5 and 2.9 are sub-rectangular, and they are rectangular if the proportion is ≥3.0.width proportion smaller than 2.49 are described as paraquadrate, those with proportions between 2.5 and 2.9 are sub-rectangular, and they are rectangular if the proportion is ≥3.0.In the descriptions, size refers to the combined length of head and trunk, excluding antennae and furcula.Some caves in Mexico and South America are well known, and coordinates for entrances can be easily found by an online search.The actual location for other collecting sites could not be determined based on original descriptions.Therefore, coordinates for cave locations should be treated as approximations, within 1 km distance from the entrance.
Abbreviations used in the text, tables, and figure captions are as follows: Abd. for abdomen; Ant. for antenna(e), BT for basal paired teeth of unguis, Mc for macrochaeta, and Th. for thorax.

Annotated Checklist of Neotropical Trogolaphysa with 0-5 Eyes
All measurements for previously described species were obtained from published drawings.Complete descriptions are provided for the new species.For already described species, we present abbreviated descriptions comprising characters most often included in the original descriptions.Abbreviated descriptions include body size, color, eye number, dorsal chaetotaxy (when available), prelabral chaetae ornamentation, labial triangle chaetotaxy, claw complex morphology, and mucro shape, and number of teeth.Dorsal macrochaetotaxy is summarized using the short formula proposed above.The In the descriptions, size refers to the combined length of head and trunk, excluding antennae and furcula.Some caves in Mexico and South America are well known, and coordinates for entrances can be easily found by an online search.The actual location for other collecting sites could not be determined based on original descriptions.Therefore, coordinates for cave locations should be treated as approximations, within 1 km distance from the entrance.
Abbreviations used in the text, tables, and figure captions are as follows: Abd. for abdomen; Ant. for antenna(e), BT for basal paired teeth of unguis, Mc for macrochaeta, and Th. for thorax.

Annotated Checklist of Neotropical Trogolaphysa with 0-5 Eyes
All measurements for previously described species were obtained from published drawings.Complete descriptions are provided for the new species.For already described species, we present abbreviated descriptions comprising characters most often included in the original descriptions.Abbreviated descriptions include body size, color, eye number, dorsal chaetotaxy (when available), prelabral chaetae ornamentation, labial triangle chaetotaxy, claw complex morphology, and mucro shape, and number of teeth.Dorsal macrochaetotaxy is summarized using the short formula proposed above.The macrochaetotaxy of several species is only partially described and the gaps in knowledge are represented in the short formula by questions marks (e.g., ??/40/3 + 3 means the state of the dorsal macrochaetae of the head is unknown).The claw complex is illustrated for all species described before 2022.
A few other useful diagnostic characters are not included in the short descriptions because they have been reported for only a handful of recently described species.The excluded diagnostic characters are presence/absence and shape of distal labral papillae, number of appendages on the sublobal plate of the outer maxillary lobe, shape of the lateral appendage on labial papilla E, and number of lenticular organs on the intersegmental membrane between Abd. 4 and Abd. 5.The number of ocellar setae appears to be useful for diagnosing species with 6-8 eyes, but it is not included because the absence of eyes makes it almost impossible to determine the actual number and homology of chaetae.The relative size of chaetae on the proximal row of the labrum may also contain good diagnostic information, but it is rarely reported.All these characters should be revisited and reported for all species.A more extensive discussion of the diagnostic value of additional character systems can be found in [3,19,20,22].
Synonymies are not exhaustive; they are limited to changes in nomenclature, new distributional records, identification keys, and redescriptions.Citations of new combinations in the synonymy follow the current convention of author publication year: page where species is mentioned, and brief explanation of citation context.All other references in the synonymy are cited as authors (publication year): page.
All species were collected in caves, unless otherwise noted.

Type Material Repository
Holotypes and one paratype of each new species are deposited at the Florida State Collection of Arthropods (FSCA).All other type material is deposited at the Northern Arizona University (NAU) collection.
Remarks.Trogolaphysa aelleni is probably a troglobiont and the only white member of the genus with 2 + 2 individually pigmented eyes, ciliate prelabral chaetae, three inner ungual teeth, and a long and narrow lanceolate unguiculus.
Remarks.This presumed troglobiont is the only eyeless species with two inner teeth inserted on basal quarter of unguis and basally swollen, tear-shaped unguiculus.Based on claw shape, T. bessoni is most similar to T. equatorica (Palacios, Ojeda and Christiansen) but whereas in T. bessoni the unguiculi on all legs are of similar shape, in T. equatorica the fore and hind leg unguiculi are different (Figure 2C, D).In addition, the hind leg unguiculus is much shorter (0.58× unguis) in T. bessoni than in T. equatorica (0.72× unguis).
The original description states that the dorsal macrochaetotaxy of T. bessoni is similar to that in Trogolaphysa cotopaxiana Thibaud and Najt, but the rendering of the general distribution of macrochaetae for that species lacks the detail needed to infer the homology of elements on Abd. 4.
Remarks.The Venezuelan species is a troglobiont unique among eyeless species with three inner ungual teeth in having the basal teeth asymmetric and unequal, with the lunate tooth much larger than the wedge-shaped tooth.All other eyeless species with three inner ungual teeth have subequal or marginally unequal size teeth.
Remarks.Among eyeless species with four inner ungual teeth, this is the only troglobiont with basal ungual teeth subequal and symmetric, four macrochaetae in the p3 complex of the mesothorax, with Abd. 4 macrochaeta A5 and more than 70 external spines on the dens.Trogolaphysa chapelensis is most similar to T. lacerta Lima, Oliveira and Zeppelini, but the later species carries six macrochaetae in the p3 complex of the mesothorax and lacks macrochaeta A5 on Abd. 4. Trogolaphysa zampauloi Lima, Oliveira and Zepelini is also similar to T. chapelensis in claw structure, but that species has four macrochaetae in series A on the head, whereas in T. chapelensis series A has only one macrochaeta.Trogolaphysa bellinii is also similar to T. chapelensis, but in the later species the tenent hair is acuminate.
Remarks.This troglobiont is the only eyeless species with acuminate tenent hair and three inner ungual teeth which also carries five macrochaetae in the p3 complex of the mesothorax and five inner macrochaetae on Abd. 4. Trogolaphysa crystallensis is most similar to T. epitychia Oliveira, Lima and Zeppelini and T. gisbertae Brito and Zeppelini but the three species differ in summary macrochaetae formula as shown in Table 1.
Remarks.This troglobiont is the only eyeless species with large, paired teeth inserted on the basal quarter of the unguis, lacking unpaired teeth, and having heteromorphic unguiculi.Claw shape is most similar to T. bessoni, also from Ecuador, but in T. equatorica the fore and hind unguiculi are different shape and neither of them approach the basally swollen, tear-shaped unguiculus present in T. bessoni.
Remarks.This presumed troglobiont is the only eyeless form with three well-marked inner ungual teeth, two anterior head macrochaetae and lacking Abd. 4 macrochaeta A5.Trogolaphysa gisbertae is most similar to T. crystallensis and T. epitychia, but they can be reliably distinguished using dorsal chaetotaxy (see Table 1).
Remarks.This presumed troglobiont is the only eyeless species with four inner ungual teeth in which one basal tooth is much larger than the other and overlaps both unpaired teeth (Figure 3E).No other species with a four-toothed unguis approaches this morphology.
14. Trogolaphysa haitica (Palacios-Vargas, Ojeda and Christiansen, 1985) [7] (Figure 2F, Table 2) Remarks.This presumed troglobiont is the only eyeless species with four inner ungual teeth in which one basal tooth is much larger than the other and overlaps both unpaired teeth (Figure 3E).No other species with a four-toothed unguis approaches this morphology.
Remarks.This troglobiont is the only eyeless member of the genus with two elongate and sharply acuminate ungual teeth, labial chaeta M2 ciliate and chaeta 'r' smooth.Trogolaphysa haitica is most similar to T. reneaui n. sp. and the differences between the two forms are discussed in the remarks to the new species.Trogolaphysa sauron Soto-Adames, Baquero and Jordana has a similar claw morphology but differs from T. haitica in having 8 + 8 eyes and a distinctive color pattern.
Remarks.This troglobiont is the only eyeless species with two inner ungual teeth, one of which is lunate and much larger than the other, and a long narrow unguiculus.All other eyeless species with two markedly unequal basal ungual teeth (i.e., T. haitica and T. reneaui n. sp.) have acuminate inner teeth and wide lanceolate unguiculi.
Remarks.This troglophile is the only Trogolaphysa species with four eyes, two minute lunate basal ungual teeth and wide lanceolate unguiculus.No other species has a similar combination of unguiculus and unguis morphology.
Remarks.This troglobiont is the only eyeless species with tridentate unguis, basally swollen unguiculus and all labial triangle chaetae, except M1, smooth.Among species for which the dorsal chaetotaxy is known, this is the only form with summary formula 52/41/47 + 6-7.Trogolaphysa jacobyi is most similar to T. marimutti (Ojeda, Palacios and Christiansen) from Mexico and T. beliziana.The Mexican species has a four-toothed mucro (three teeth in T. jacobyi), labial chaetae L1 and L2 ciliate (both smooth in T. jacobyi) and the unguiculus is lanceolate (basally swollen in T. jacobyi).The differences between T. jacobyi and T. beliziana are detailed in the remarks of T. beliziana.
Remarks.This troglobiont is the only species with 0-3 eyes, acuminate tenent hair, four well-marked ungual teeth and smooth lanceolate unguiculus that also bears six macrochaetae in the mesothoracic p3 complex and lacks Abd. 4 macrochaeta A5.Trogolaphysa lacerta is most similar to T. chapelensis, but this last species has a serrated unguiculus and a different summary macrochaetae formula (see Table 3).
Remarks.This troglobiont is the only eyeless species with the tenent hair spatulate and longer than the unguiculus, and three-toothed unguis in which the basal teeth completely overlap the unpaired tooth.Trogolaphysa mariecurieae is also unique among species with three-toothed unguis in having only three inner macrochaetae on Abd. 4 2L) with three inner teeth, all small and distributed as 27, 27, 59: basal teeth weakly lunate, symmetric, small, subequal not reaching unpaired tooth, unpaired tooth well-developed, wedge-like.Unguiculus lanceolate, 0.64× as long as inner edge of unguis, posterior margin serrate.Mucro sub-rectangular, 2.5× as long as wide, with four teeth.
Remarks.This troglobiont is the only eyeless species with acuminate tenent hair, three ungual teeth where the basal teeth are symmetric, the unguiculus is lanceolate and serrated, and labial triangle chaetae E is smooth.Five other species, T. caripensis, T. crystallensis, T. epitychia, T. gisbertae, and T. jacobyi, are eyeless, have acuminate tenent hair and three-toothed unguis; however, all of them have clearly rectangular mucrones (between 3.2 and 4.4 times as long as wide in other species and 2.5 times in T. marimutti), and in all, except in T. jacobyi, labial triangle chaetae M2 and E are ciliate (smooth in T. marimutti).Trogolaphysa jacobyi has a basally swollen unguiculus and three-toothed mucro, whereas in T. marimutti, the unguis has four teeth and the unguiculus is lanceolate.Trogolaphysa oztolica Ojeda and Palacios-Vargas, may be confused with T. marimutti if the minute distal unpaired tooth is overlooked.However, in T. oztolica labial chaetae E is coarsely ciliate and the inner membrane of the unguiculus is weakly excavate (see Figures 2L and 3D).
Remarks.This is the only eyeless species with four large inner ungual teeth where the basal teeth are asymmetric and overlap the proximal unpaired tooth, the tenet hair is longer than the unguiculus, and the mucro is short and almost square.
Trogolaphysa delamarei was described from individuals collected at a single cave in Cuba and according to the original description, it differs from T. maya in the shape and relative size of the basal teeth of the unguis and in having a smooth unguiculus.Gruia [6] provided details of the dorsal and labial chaetotaxy of T. delamarei based on type material from Cuba.In support of Massoud and Gruia's [33] justification for recognizing T. delamarei, the original description shows a claw complex with unequal but symmetric basal teeth, a smooth and broadly lanceolate unguiculus, and tenent hair shorter (0.87×) than the unguiculus.However, Thibaud and Najt [27] examined the type specimens of T. delamarei and affirmed that there were no differences in claw structure between the holotype of T. delamarei and the illustrations accompanying the original description of T. maya.Mari Mutt [33] also reported T. maya (as T. delamarei) from a cave in the Dominican Republic, potentially extending the range of the species to the neighboring island of Hispaniola.
It seems unlikely that the Mexican and Cuban/Hispaniolan populations of such a specialized form are conspecifics.An alcohol preserved syntype of T. maya deposited at the Illinois Natural History Survey is in poor condition and little information on chaetotaxy would likely be drawn for it.Therefore, in the absence of information on the dorsal chaetotaxy in the population from Yucatan, and until fresh material from Mexico is obtained, and the morphological and genetic relatedness of the Mexican, Cuban and Dominican populations is examined, we accept the synonymy proposed by Thibaud and Najt [27].
The combination of external macrochaetae on Abd. 4 illustrated by Gruia [6] is unusual in suggesting that lateral macrochaetae E3 and E4 are present but E2 is absent.Since all other species reported here carry E2 it seems possible that either the specimen Gruia chose to illustrate was not typical or that the macrochaeta was left out of the drawing by mistake.Either way, we accept the description as stated.This is the only species treated here having surface and subterranean populations, suggesting it is a troglophile.
Remarks.This is the only species with 2 + 2 eyes, three inner ungual teeth and truncate unguiculus.Trogolaphysa aelleni also has 2 + 2 eyes and three ungual teeth, but the basal teeth are minute and do not reach the unpaired tooth, and the unguiculus is lanceolate and slender.Nine other species have three inner ungual teeth (Table 1), but they either lack eyes or have a different number of eyes.This is an epigean species.
Table 2 provides diagnostic characters for all Neotropical species with two inner ungual teeth and fewer than six eyes.25.Trogolaphysa sotoadamesi Ferreira, Oliveira and Zeppelini, 2022 [3]  Furcula.Dens with two rows of ciliate spines, inner row with up to 54 spines, outer row with 50 spines.Mucro paraquadrate, 2.44 times as long as wide, with four teeth (Figure 7F).
Remarks.Trogolaphysa reneaui n. sp. is the only member of the genus with summary chaetotaxy formula 42/42/45 + 7.In addition, the new species is the only form with 0 + 0 to 1 + 1 eyes, inner edge of hind claw with two teeth, tenent hair acuminate and subequal in length to the unguiculus, and labial microchaeta r ciliate.Four other species (T.barroca, T. haitica, T. hauseri and T. sotoadamesi) are eyeless, carry two inner ungual teeth and have a four-toothed mucro.The species most similar to T. reneaui n. sp. is T. haitica, which shares the same general shape of the hind ungues.However, the two species differ in that the tenent hair is shorter (0.62×) relative to the unguiculus in T. haitica (up to 1.08× in T. reneaui n. sp.), and in having labial triangle chaeta M2 ciliate and r smooth (chaeta M2 smooth and chaeta r coarsely ciliate in T. reneaui n. sp.).Trogolaphysa hauseri also has only two inner ungual teeth, but they are asymmetric (symmetric in the new species) and the unguiculus is lanceolate narrow (lanceolate wide or weakly truncate in the new species).Trogolaphysa barroca and T. sotoadamesi also have two-toothed unguis but they have five macrochaetae in the p3 complex on Th. 2 and do not carry macrochaetae on Th. 3, whereas in the new species the p3 complex on Th. 2 carries three macrochaetae and Th. 3 carries two macrochaetae.
Remarks.This troglobiont is the only eyeless species with two well-marked asymmetric inner ungual teeth, four mucronal teeth, and Abd. 4 with macrochaeta Te3.Trogolaphysa sotoadamesi is most similar to T. barroca, but whereas in the latter form the basal ungual teeth are asymmetric (one wedge-like and one lunate), in the former species both basal teeth are lunate.
Remarks.This troglophile is the only species of Trogolaphysa with 5 + 5 eyes, spatulate tenent hair and three small ungual teeth.None of the other species with reduced eye number approaches T. strinatii.According to Yoshii [5], T. strinatii is similar to Mexican populations of what he identified as T. carpenteri (Denis), however, T. carpenteri has 8 + 8 eyes and smooth prelabral chaetae, whereas T. strinatii has 5 + 5 eyes and ciliate prelabral setae.
Remarks.No other Neotropical member of Trogolaphysa has 2 + 2 eyes, two unequal inner ungual teeth, and truncate unguiculus.Only T. millsi and T. trioculata Soto-Adames also have a clearly truncate unguiculus, but both species have three inner ungual teeth.
The presence of color pattern and collection location suggest this is a troglophile.The species was collected in leaf litter in a cave and in surface forest.
Distribution.Brazil, Rio de Janeiro, Maciço da Tijuca, in an unnamed grotto and in surface forest leaf litter, S 22.9521, W 43.2907.
Remarks.This is the only species of Trogolaphysa with three ungual teeth, 3 + 3 eyes and truncate unguiculus.The species is also unique in the peculiar asymmetry and distal displacement of one basal ungual tooth (Figure 2O).Trogolaphysa millsi is the only other member of the genus with three ungual teeth and (weakly) truncate unguiculus, but the basal teeth are paired, subequal, and considerably larger than the proximal unpaired tooth (Figure 2N).
Trogolaphysa trioculata was collected in surface leaf litter and despite having a reduced number of ocelli it is not associated with subterranean habitats.
Remarks.No other species of Trogolaphysa has two eyes, unguis with four inner teeth, two metathoracic macrochaetae, and acuminate tenent hair.In addition, T. welchi n. sp. is the only member of the genus with the summary macrochaetae formula 32/72/35+13-14.Trogolaphysa bellinii from Brazil is the only other Neotropical species with 2 + 2 eyes and four inner ungual teeth, but the Brazilian species has spatulate tenent hair (acuminate in T. welchi n. sp.), lacks metathoracic macrochaetae (two in the new species) and has seven posterior chaetae on Abd. 4 (13-14 chaetae in the new species).Furcula.Dens with two rows of ciliate spines, in males both rows with up to 33 spines; largest female with 44 inner and 34 outer spines.Mucro paraquadrate, 2.26× as long as wide, with four sequential teeth (Figure 9H).
Remarks.No other species of Trogolaphysa has two eyes, unguis with four inner teeth, two metathoracic macrochaetae, and acuminate tenent hair.In addition, T. welchi n. sp. is the only member of the genus with the summary macrochaetae formula 32/72/35 + 13-14.Trogolaphysa bellinii from Brazil is the only other Neotropical species with 2 + 2 eyes and four inner ungual teeth, but the Brazilian species has spatulate tenent hair (acuminate in T. welchi n. sp.), lacks metathoracic macrochaetae (two in the new species) and has seven posterior chaetae on Abd. 4 (13-14 chaetae in the new species).
The reduced number of eyes, pigment, the relative length of the antennal, and the fact that it was collected deep in the dark zone indicate this species is a troglobiont.
Remarks.This troglobiont is the only eyeless member of the genus with serrated unguiculus, all ungual teeth acuminate and elongate, and labial chaetae r, E, L1 and L2 smooth.The organization of inner ungual teeth in T. xtolokensis is similar to that in T. variabilis, but the shape and size of the teeth is quite distinct (see Figure 3C,G).Only T. maya has unpaired ungual teeth as well-developed as in T. xtolokensis, but they differ in shape (in T. maya three teeth are wedge-shaped, whereas in T. xtolokensis all are acuminate); in addition, the basal teeth in T. maya are asymmetric and reach the proximal unpaired tooth whereas in T. xtolokensis the basal teeth are symmetric and do not reach the unpaired teeth.
Remarks.This troglobiont is the only species with four inner ungual teeth in which the basal teeth are symmetric, subequal and well-marked, there are four anterior head macrochaetae and the mesothoracic p3 complex has five macrochaetae.The general morphology of the unguis in T. zampauloi is similar to that in T. bellini, T. chapelensis, T. lacerta, T. oztolica, and T. variabilis, but T. bellini has a spatulate tenent hair (acuminate in T. zampauloi), T. oztolica has an excavate unguiculus (lanceolate in T. zampauloi), T. variabilis has a smooth M2 in the labial triangle (ciliate in T. zampauloi), and T. chapelensis and T. lacerta have only one anterior head macrochaeta (four in T. zampauloi).

Character Analysis
1. Ratio antennal length to head diagonal.This is a continuous character and as such difficult to use for diagnosis.Partitions are arbitrary, and only useful to diagnose species with ratios at the ends of the distribution (antennae either much longer or much shorter than the average).The problem is compounded because head measurements may not be consistent across authors.Head diagonal is typically measured on a sideview of the head, from its posterior margin to the tip of mouth cone; however, some authors measure the head on flattened, slide-mounted specimens, which consistently yields shorter head lengths.Some authors (e.g., [2,3,22]) calculate the antennal ratio with respect to trunk length, instead of head length.Although this new ratio may be more consistent than the traditional ratio, it prevents comparisons with most published data.
Additionally, it is unclear that in Trogolaphysa long antennae is a result of adaptation to cave habitats, as many surface species also have long antennae (see [20,22]).
2. Eye Number.All states, from 0 + 0 to 5 + 5, are represented in the species included here, but the most common character state is absence of eyes (in 20 species).Four species have been reported as having a variable number of eyes per side (e.g., T. zampauloi with 0 or four, T. bellini with 0 or three, T. lacerta with 0 or two, and T. reneaui n. sp.0 or one); the appearance of variability may be an artifact of the slide mounting process.It is possible that in some specimens the eyes were over cleared during the digestion process, thus giving the appearance of being eyeless when they are not.This matter may be settled by the examination of several specimens under a scanning electron microscope.
Eye number is considered a character that responds readily to adaptive pressure in subterranean systems [38], but it is not clear if eye reduction is the direct result of selective pressure to subterranean life or a preadaptation derived from living in soil.Typical soil forms have relatively short appendages, irrespective of eye number, whereas cave-adapted species tend to have long antennae, legs, and furcula [4,38].If most of the reduction in eye number took place in the soil, before the species colonized caves, we would expect incongruence between eye number and the level of adaptation to subterranean life in other characters.This should be further evaluated.
3. Paired Dorsal Macrochaetae of the Head.There is complete information for 19 species, whereas for 13 species the information is incomplete or totally absent.Eleven paired macrochaetae are varible in comparisons between species; a twelfth macrochaeta, A2, is always present.The order in which macrochaeta are added in comparisons between species is not fixed beyond the observation that all species with three macrochaetae carry A2, Pa5, and one other macrochaeta, and all species with four macrochaeta have A2, Pa5, Pm3, and one other macrochaeta.Macrochaeta A3 is always present when there are five or more macrochaeta, and M2 is always present if there are more than seven macrochaetae.There are 10 patterns of macrochaetae; the most common pattern is the presence of three macrochaetae in the combination of A2, Pa5, and Pm3, and is shared by eight species.All other patterns are present in one or two species.
4. Ornamentation of Prelabral Chaetae.All species have four prelabral chaetae and they are either ciliate or smooth.This character has been reported for all species except T. millsi, T. tijucana, T. caripensis, and T. maya.
5. Labral Chaetae.All reported species fit the formula 554.Characters derived from the labral chaetae are not included in the summary description because the chaetae are smooth in the 27 species for which we have information.There are other potentially diagnostic characters to be found on the labral chaetae, but they have not been reported for most species.For example, the external chaetae of the proximal row maybe shorter (chaeta B2 in figure 27 in [2]), subequal (chaeta C2 in figure 4B in [28]) or much longer (chaeta p2 in Figures 5D and 8E here) than the inner chaetae.This character system merits further evaluation.
6. Labral Papillae.This character has been reported for 17 of the 33 species treated here.Only two character states are found among the species reported: the papillae are either absent or independent and unfused.This contrasts with surface species which display several levels of fusion and papilla shape transformations (e.g., [2,20]).
7. Labial Triangle Chaetotaxy.This character is almost always reported and is described for 30 of the 32 species.The only states scored are whether the chaetae are smooth or ciliate.All chaetae on the anterior row are smooth and variation is limited to the posterior row.Chaeta M1 is invariably ciliate, but all other chaetae can be either ciliate or smooth.There are eight patterns of chaetae but the most common pattern, present in 21 species, is M1M2rEL1L2, (all chaetae ciliate, except r).Two patterns are shared by two species each and the other five patterns are autapomorphic.
8. Number of Chaetae Along Cephalic Groove.As circumscribed here, this character only refers to the number of chaetae inserted along the section of the ventral groove found on the head.This character has been reported for 18 species.The number of chaetae varies from 3 to 8 but most species have 4 chaetae.The number of chaetae along the ventral groove (and anywhere else on the post-labium) seems to be related to the density of scales on the ventral face of the head.Species with a less dense scale cover tend to have more chaetae (e.g., T. jacobyi, see [2]).This may be one of the few chaetotacic characters that reflects adaptation to subterranean life.However, the density of scales on the ventral surface of the head has been poorly reported in the literature and the meaning of the variation observed in the number of chaetae along the ventral groove is unclear.9. Number of Macrochaetae in p3 Complex of the Mesothorax.This character refers to the number of setae with enlarged sockets forming a cluster on the medio-posterior area of Th. 2 (Figures 5B and 8B).Macrochaetae in the p3 complex almost invariably fall off during the mounting process, and their condition is derived from the relative size of the sockets.This character has been reported in 19 species and is present in three states: three, five, or six macrochaetae.The distribution of the states among species is even, with two groups of seven species each having three or five macrochaetae, and a group of five species with six macrochaetae.
10. Number of Metathoracic Macrochaetae.This character has been reported for 19 species and there are four character states: 14 species lack macrochaetae, one species has one macrochaeta, two species carry two macrochaeta, and two species bear three macrochaetae.
11. Fourth Abdominal Segment Inner Macrochaetae.There is complete information for 18 species.In T. bessoni, the homology of the chaetae is intractable from the information provided in the original description.For 13 species, no information is available.
Across species, the number of macrochaetae varies from three to five.Macrochaetae B5 and B6 are fixed and present in all species and macrochaeta A3, A5, and B4 are variable.The pattern of macrochaeta addition is not fixed: species with three macrochaetae carry B5, B6, and either A5 or B4, whereas species with four macrochaetae have B5, B6, plus two others in any combination of A3, A5, or B4.As a result, there are six patterns of macrochaetae.The most common number of macrochaetae is four (ten species), but the most common pattern is the combination of all five macrochaetae.
There are two other sources of variation in this system, the shape of the macrochaetae, and their insertion relative to other components of the chaetotaxy.Macrochaetae can be relatively short and parallel sided or strongly tapered and long.That difference is not clearly reflected by the sockets in this system and could be scored only if the macrochaeta cover remains intact on the mounted specimens.Thus, the diagnostic utility of macrochaeta shape in this system may remain unfulfilled.Exploration of the relative position of the macrochaetae as a source of diagnostic information may prove more fruitful.
The traditional characters scored for the dorsal chaetotaxy of Abd. 4 are the number of macrochaetae, their combination, and shape.However, there is also considerably variation among species in macrochaetae insertion with respect to each other, to the pseudopore, and the bothriotricha complex.This information is easily extracted from drawings of the specimens.It is recommended that drawings of actual chaetae distributions (e.g., Figure 9C) be published, even if maps of macrochaetae distribution are also included with the descriptions (e.g., Figure 8B).The spatial distribution of macrochaetae is not considered here but will be further examined in a future study.
12. Fourth Abdominal Segment Outer Macrochaetae.There is complete information on this system for 18 species.The homology of chaetae in T. bessoni is not discernable from the original drawings, and information is lacking for 13 species.
This system is more difficult to circumscribe than the inner macrochaetae because there are differences in the number, arrangement, and relative shape of the elements, all of which are reflected by the sockets.For the purpose of this study, we have restricted the observations to the subset of primary outer macrochaetae: D3, E1, E2, E3, E4, F1, F2, and F3.The only secondary macrochaeta considered here is Te3 because it is inserted close to D3 and is unlikely to be missed if elements in series E and F are illustrated.Other secondary macrochaeta, such as Fe2 and Fe3, are often well-developed, but they are external to column F and may be omitted from illustrations; thus, they are not considered here.The discussion that follows is then limited to the number of primary elements and their combination patterns.
The number of macrochaetae varies from four to seven, with most species (eleven) carrying six.There are seven combinations of the eight macrochaetae, and no single species carries all macrochaetae.Elements D3, E3, and F1 are invariably present; D3 and F1 are always parallel-sided macrochaetae with large sockets, whereas in six species E3 is a long, strongly tapered chaeta with the socket distinctly smaller than that of D3 and F1.Element E2 is only absent in T. maya, but the drawing provided by [6] is difficult to interpret and, in fact, the missing element may be E4.Most of the variation is attributable to the presence or absence of F2, F3, and E4 and to the relative size of E3 and E4.Presence or absence of F2 is unambiguous in all species and the most useful diagnostic character of the lateral chaetotaxy.Macrochaeta Te3 is present only in T. sotoadamesi.
13. Number of Posterior Chaetae on the Fourth Abdominal Segment.This character is included because in species with six to eight eyes, the number of chaetae is variable and diagnostic.However, this character has been reported in only four of the 32 species included here.Three species have seven chaetae, and the fourth species has 13-14 chaetae.
14. Shape and Relative Length of Tenent Hair.All original descriptions have illustrations of the tenet hair of the hind legs or provide explicit descriptions of the characters considered here.Variation in the tenet hair can be coded into two characters: the relative size of the chaeta and the shape of its tip.A third character, whether the chaeta is smooth or ciliate, is not included here because all species with 0 + 0 to 5 + 5 eyes have smooth tenent hair.The shape of the tip is a discrete character with two states, the tip can be either acuminate or capitate spatulate.In species where the spatula is small, the tip of the chaeta appears to be rounded on side views.However, dorsoventral views invariably show the tip to be spatulate.The relative size of the chaeta is reported in relation to the length of the unguiculus.The size of the chaeta is continuous, from less than half the length of the unguiculus to longer than the unguiculus.Tenent hairs with acuminate tips span the range of sizes, from less than half to subequal to the unguiculus.Species with spatulate tips invariable have tenent hairs subequal to, or longer than, the unguiculus.
15. Number, Shape, and Spread of Inner Teeth on Hind Legs.The hind claw complex has been illustrated or described for all species.There are at least seven characters that can be derived from unguis morphology, but here we consider only four: number of teeth; inner teeth spread; inner teeth shape; and inner teeth relative size.
The number of inner teeth varies from two to four.Teeth may originate anywhere along the inner edge of the unguis, but the basal pair (BT) are never inserted on the distal half (the most distal BT origin is 49, in T. lacerta) whereas the two unpaired teeth are usually inserted on the distal half.The number of teeth and their spread are not correlated, although when only the BT are present, they are most likely inserted on the basal quarter of the inner edge.The two exceptions to this generality are T. dandarae with the BT originating at 39, and T. tijucana, with BT at 43.Otherwise, the spread of teeth is diagnostic, even if the continuous nature of the states makes it difficult to apply.
In most species, teeth take one of three distinct shapes: they can be lunate (Figure 2A), acuminate (Figure 2F), or wedge-shaped (Figure 2N).The shape of at least one tooth in T. barroca, T. hauseri, and T. caripensis is difficult to assign to either of the three classes, but seems to be transitioning between wedge and lunate, and they have been designated as transitional lunate.In most species, the BT are the same shape, and are referred to as symmetric.However, in T. trioculata, T. maya, and T. caripensis, each basal tooth is a different shape, and thus, the teeth are asymmetric.The size of teeth also varies across species; in some species, the BT are of different size.We describe as minute those teeth barely visible at 400× (Figures 2I and 3D); teeth are small when they do not project much (Figure 2M,K), developed teeth are projected (Figure 2A,D), and well-developed teeth are relatively large (Figures 2F and 3B,C).The term enlarged is used only for the largest tooth in uneven-sized BT, and the enlarged tooth is usually wedge-or transitional-lunate-shaped (Figure 2E,J and Figure 3E).The proximal unpaired tooth is never larger than the BT and the distal unpaired tooth is most often minute or absent.
16. Unguiculus Shape.The unguiculus has been illustrated for all species.Three general shapes are represented across species: lanceolate, basally swollen, or truncate.Three species (T.tijucana, T. millsi, and T. trioculata) have truncate unguiculus; the unguiculus is clearly basally swollen in T. bessoni, and T. jacobyi, and weakly swollen in T. beliziana and T. ecuatorica; whereas all other species show variations in shape that can be generally described as lanceolate.The term lanceolate fails to address variation that encompasses unguculi that are very narrow (T.aelleni and T. hauseri), asymmetrically convex (T.marimutti, T. ecuatorica, and most other species), or symmetrically convex (T.honduraensis).17.Number of Teeth and Mucro Shape.The mucro has been reported for all species.The number of teeth varies from three to five, but the vast majority carries four teeth.Trogolaphysa beliziana, T. jacobyia, and T. dandarae have three teeth, whereas T. ecuatorica is the only species with five real teeth.
The shape ratio length/width varies from 1.93 to 4.35.Seventeen species have rectangular mucrones (shape ratio of ≥3.00), in six species the mucro is sub-rectangular (2.50 to 2.99), and in five species it is paraquadrate (shape ratio 2.00 to 2.49).Only T. guacharo has an almost square mucro.All species with three or five teeth have rectangular mucrones.

Identification Key to Neotropical Species of Trogolaphysa with 0 + 0 to 5 + 5 Eyes a
Thirty-three species of Neotropical Trogolaphysa have been described as having a reduced eye number (Tables 1-3).The complete dorsal chaetotaxy is known for seventeen species; for one species, drawings were so diagrammatic that no homology of elements was possible; there was partial information on three other species.No chaetotaxy information was available for thirteen species.Given the information gap on dorsal chaetotaxy, the key below is based on eye number, labial triangle chaetotaxy, hind claw complex, and mucro morphology.Dorsal chaetotaxy is used to separate only a few of the most recently described species.
1a  [26], T. delamarei is a junior synonym of T. maya and therefore it is not included in the key.See additional comments under the remarks to T. maya.
b. Specimens of T. oztolica will key out here if the minute distal unpaired tooth is not seen clearly.However, in T. oztolica all labial chaetae are ciliate, except r, the basal inner teeth are wedge-shaped, subequal and small, and the inner membrane of the unguiculus is weakly excavate.

Discussion
The independent evolution of cave systems in different geographic regions, with the concomitant development of unique underground assamblages derived from local surface communities, provide the ideal experimental conditions to study the evolution of morphological adaptations.The genus Trogolaphysa is one of several springtail genera that have radiated extensively in subterranean environments across the Americas [4].Other genera with many specialized subterranean species, like Pseudosinella and Pygmarrhopalites Vargovitsh, have centers of diversification in temperate North America and Eurasia, whereas Trogolaphysa has diversified in the neotropics, a region that has received relatively little attention.Factors that have discouraged the study of Trogolaphysa include the absence of a clear understanding of the morphology and character systems that reflect species-level discontinuities; access to the scattered scientific literature necessary to identify cave-adapted Trogolaphysa; and a lack of synthetic treatment of described species.A series of recent papers [10,19,21] have helped to circumscribe character systems that consistently identify independent lineages.
The main goal of this contribution was to synthesize available diagnostic information about all species of Trogolaphysa with 0 to 5 + 5 eyes.The purpose of early descriptions was to diagnose putative new forms from the few other forms already known.Descriptions were not intended to provide data to evaluate phylogenetic relationships between species or adaptive evolutionary pathways.Hence, species descriptions were incomplete by current standards.Although the breadth of characters included in descriptions gradually increased over time (compare the transition from [23,28] through [7] and [5]), it was not until [10] that descriptions began to include explicit statements of the dorsal chaetotaxy.Mari Mutt [10] further expanded descriptions to include characters of the chaetotaxy routinely reported for two genera of scaled Entomobryidae with similarly reduced macrochaetotaxy (Lepidocyrtus and Pseudosinella), but never explored in Trogolaphysa.
Soto-Adames et al. [19] presented a list of 24 character systems found to provide information useful for species identification.The evaluation of 32 species in the present study reaffirms the diagnostic value of classical characters and confirms the diagnostic utility of chaetotaxy.All species for which chaetotaxy has been reported (19 of 32) can be diagnosed using the combined distributions of macrochaetae on the head, thorax, and fourth abdominal segments-that is, the information synthesized in the summary macrochaetae formula.The diagnosis of species differing even by a single macrochaeta on the head or trunk is supported by other characters of the chaetotaxy (i.e., condition of prelabral chaetae, the number of post-labial chaetae, etc.) and/or structural characters (i.e., number of eyes, claw and mucro shape, and claw teeth pattern).In addition to the evident value of a larger number of characters, chaetotaxy provides an independent set of characters to evaluate hypotheses about the evolution of subterranean adaptations.Among Trogolaphysa with 0 to 5 + 5 eyes, classical diagnostic characters (eye number, morphology of hind leg claw complex, and mucro) show strong response to adaptive evolution [4,38], whereas the chaetotacic characters evaluated here were largely uncorrelated to the level of adaptation to the subterranean environment.This is consistent with a previous phylogenetic analysis of a limited number of species showing that chaetotacic characters supported clades of species congruent with geographic distribution, whereas structural characters supported clades congruent with habitat distribution (Soto-Adames and Taylor [2]).The polarity of putative subterranean adaptive characters must be evaluated as part of a larger data set that also includes surface species.A cursorial review of surface forms shows that large antennal length/head diagonal and mucro shape ratios are not an exclusive characteristic of cave-adapted species (see [20,22,39] for some examples).The condition of some structural characters in several surface lineages may be the reason for the success of Trogolaphysa colonizing deep cave habitats.

Figure 7 .
Figure 7. Trogolaphysa reneaui n. sp.(A) Fourth abdominal segment, arrangement of dorso-lateral chaetotaxy in a different individual.(B,C) Hind claw complex in female and male, respectively, tooth shown in (B) is homologous to left tooth in (C).(D) Ventral view of basal teeth.(E) Different perspective of hind unguiculus in female.(F) Mucro.Furcula.Dens with two rows of ciliate spines, inner row with up to 54 spines, outer row with 50 spines.Mucro paraquadrate, 2.44 times as long as wide, with four teeth (Figure 7F).Remarks.Trogolaphysa reneaui n. sp. is the only member of the genus with summary chaetotaxy formula 42/42/45+7.In addition, the new species is the only form with 0 + 0 to 1 + 1 eyes, inner edge of hind claw with two teeth, tenent hair acuminate and subequal in length to the unguiculus, and labial microchaeta r ciliate.Four other species (T.barroca, T. haitica, T. hauseri and T. sotoadamesi) are eyeless, carry two inner ungual teeth and have a four-toothed mucro.The species most similar to T. reneaui n. sp. is T. haitica, which shares the same general shape of the hind ungues.However, the two species differ in that the tenent hair is shorter (0.62×) relative to the unguiculus in T. haitica (up to 1.08× in T. reneaui n. sp.), and in having labial triangle chaeta M2 ciliate and r smooth (chaeta M2 smooth and chaeta r coarsely ciliate in T. reneaui n. sp.).Trogolaphysa hauseri also has only two inner ungual teeth, but they are asymmetric (symmetric in the new species) and the unguiculus is lanceolate narrow (lanceolate wide or weakly truncate in the new species).Trogolaphysa barroca and T. sotoadamesi also have two-toothed unguis but they have five macrochaetae in the p3 complex on Th. 2 and do not carry macrochaetae on Th. 3, whereas in the new species the p3 complex on Th. 2 carries three macrochaetae and Th. 3 carries two macrochaetae.Table2provides diagnostic characters for all Neotropical species with two inner ungual teeth and fewer than six eyes.

Figure 7 .
Figure 7. Trogolaphysa reneaui n. sp.(A) Fourth abdominal segment, arrangement of dorso-lateral chaetotaxy in a different individual.(B,C) Hind claw complex in female and male, respectively, tooth shown in (B) is homologous to left tooth in (C).(D) Ventral view of basal teeth.(E) Different perspective of hind unguiculus in female.(F) Mucro.

Table 1 .
Diagnostic table for Neotropical species of Trogolaphysa with fewer than six eyes and unguis with three inner teeth; BT = paired basal teeth of unguis; Mc = macrochaetae.

Table 2 .
Diagnostic table for Neotropical species of Trogolaphysa with fewer than six eyes and unguis with two inner teeth; BT = paired basal teeth of unguis; Mc = macrochaetae.

Table 3 .
Diagnostic table for Neotropical species of Trogolaphysa with fewer than six eyes and unguis with four inner teeth.All species also have 4-toothed mucro; BT = paired basal teeth of unguis; Mc = macrochaetae.