Redescription of Stolephorus ronquilloi Wongratana, 1983 and Description of Stolephorus hindustanensis , a New Anchovy from the Western Coast of India (Teleostei: Clupeiformes: Engraulidae) †

: The new anchovy Stolephorus hindustanensis n. sp., described on the basis of 11 specimens collected from Mumbai, western coast of India, closely resembles Stolephorus ronquilloi Wongratana, 1983 in sharing an indented preopercle posterior margin, long maxilla extending beyond the preopercle posterior margin, double pigmented lines on the dorsum behind the dorsal ﬁn, and lacking a predorsal scute. However, the new species differs from S. ronquilloi in having lower counts of gill rakers on the ﬁrst and second gill arches, higher counts of total vertebrae, a deeper body, greater distances between the snout tip and anal-ﬁn origin, origins of the dorsal and anal ﬁns, and pelvic-ﬁn insertion and anal-ﬁn origin, and longer pelvic ﬁn, third dorsal-ﬁn ray, third anal-ﬁn ray, and postorbital length.


Materials and Methods
Counts and proportional measurements followed Hata and Motomura (2017) [19]. All measurements were made to the nearest 0.01 mm using digital calipers. Standard and head lengths are abbreviated as SL and HL, respectively. "Pelvic scute" refers to a scute joined to the pelvic girdle, and "prepelvic scute", "postpelvic scute" and "predorsal scute" to hard spine-like scutes anterior to the pelvic fin, posterior to the pelvic fin, and just anterior to the dorsal-fin origin, respectively. Osteological characters, including vertebral counts, were observed on 11 specimens each of S. ronquilloi and the new species. Abbreviations are as follows-SL: standard length; HL: head length; and UGR, LGR, and TGR: rakers on upper limb, lower limb, and total gill rakers, respectively, with associated numbers indicating the specific gill arch. Institutional codes follow Sabaj (2020) [20]. Wongratana, 1983 [English name: Ronquillo's Anchovy] Figure 1; Tables 1-3

Stolephorus ronquilloi
Description. Data for holotype presented first, followed by data for other specimens in parentheses (if different). Counts and measurements expressed as percentages of SL or HL are given in Tables 1 and 2. Body laterally compressed, elongate, deepest at the dorsal-fin origin. Dorsal profile of head and body slightly convex from snout tip to dorsal-fin origin, gently lowering to the uppermost point of the caudal-fin base. Ventral profile of head and body slightly convex from lower-jaw tip to pelvic-fin insertion, thereafter slowly rising to lowermost point of the caudal-fin base. Abdomen somewhat rounded, covered with seven (five or seven) spine-like scutes. Pelvic scute without a spine. Postpelvic and predorsal scutes absent. Anus just anterior to anal-fin origin. Snout tip rounded; snout length less than eye diameter. Mouth large, inferior, ventral to body axis, extending backward beyond posterior margin of eye. Maxilla rather long, its posterior tip pointed, just reaching (short of or slightly beyond) posterior margin of preopercle. Lower jaw slender. Single row of conical teeth on each jaw and palatines. Several distinct conical teeth on vomer. Teeth patch on pterygoid. One or two rows of conical teeth on upper edges of basihyal and basibranchial. Eye large, round, covered with adipose eyelid, positioned laterally on head above horizontal through pectoral-fin insertion, visible in dorsal view. Pupil round. Orbit elliptical. Nostrils close to each other, anterior to orbit. Posterior margin of preopercle distinctly indented. Subopercle and opercle with smoothly rounded posterior margins. Gill membrane without serrations. Interorbital space flat, width less than eye diameter. Pseudobranchial filaments present, length of longest filament shorter than eye diameter. Gill rakers long, slender, rough, visible from side of head when mouth opened. Single row of asperities on anterior surface of gill rakers. Isthmus muscle long, reaching anteriorly to posterior margin of gill membranes. Urohyal hidden by isthmus muscle, not visible without dissection. Gill membranes on each side joined distally, isthmus muscle mostly exposed, not covered by gill membrane. Body scales deciduous, completely lacking on specimens, except for prepelvic scutes. Head scales absent. Lateral line absent. Fins scaleless, except for broad triangular sheath of scales on caudal fin. Dorsal-fin origin posterior to vertical through base of last pelvic-fin ray, slightly posterior to middle of body. Dorsal and anal fins with three anteriormost rays unbranched and closely spaced. First dorsal-and anal-fin rays minute. Anal-fin origin just below base of seventh (seventh to ninth) dorsal-fin ray. Posterior tip of depressed anal fin not reaching caudal-fin base. Uppermost pectoral-fin ray unbranched, inserted below midline of body. Posterior tip of pectoral fin not reaching to pelvic-fin insertion. Dorsal, ventral, and posterior margins of pectoral fin nearly linear. Pelvic fin shorter than pectoral fin, insertion anterior to vertical through dorsal-fin origin. Posterior tip of depressed pelvic fin not reaching to vertical through dorsal-fin origin. Caudal fin forked, posterior tips pointed.
Coloration of preserved specimens. Body uniformly pale yellow. Light ivory longitudinal band running from just behind upper opercular margin to caudal-fin base. Head uniformly light yellow. No black spots on suborbital area. A pair of dark patches on parietal region and a few pigment spots on occipital area. Scale pockets on dorsum with black posterior margin. Melanophores scattered along bases of dorsal and anal fins. Double pigmented lines dorsally posterior to dorsal fin. All fins transparent, melanophores scattered along fin rays of caudal fin and anterior part of dorsal fin. Caudal fin with black upper and posterior margins.
Remarks. Stolephorus ronquilloi was described by Wongratana (1983) [1] based on 15 type specimens and 59 non-type specimens collected from the Philippines. Subsequently, the species has appeared in revisional studies of the genus [3,4], or some ichthyofaunal studies (e.g., [5,21]). No studies however indicated voucher specimens, except for Hata et al., (2020) [16] who used the holotype of the species to compare with their new species. Because additional specimens have never been reported, non-type specimens reported in this study represent the second record of the species.
Remarks. Stolephorus ronquilloi was described by Wongratana (1983) [1] based on 15 type specimens and 59 non-type specimens collected from the Philippines. Subsequently, the species has appeared in revisional studies of the genus [3,4], or some ichthyofaunal studies (e.g., [5,21]). No studies however indicated voucher specimens, except for Hata et al., (2020) [16] who used the holotype of the species to compare with their new species. Because additional specimens have never been reported, non-type specimens reported in this study represent the second record of the species.
Description. Data for holotype presented first, followed by data for paratypes in parentheses (if different). Counts and measurements expressed as percentages of SL or HL are given in Tables 1 and 2. Body laterally compressed, elongate, deepest at dorsalfin origin. Dorsal profile of head and body slightly convex from snout tip to dorsal-fin origin, gently lowering to uppermost point of caudal-fin base. Ventral profile of head and body slightly convex from lower-jaw tip to pelvic-fin insertion, thereafter slowly rising to lowermost point of caudal-fin base. Abdomen somewhat rounded, covered with six (six or seven) spine-like scutes. Pelvic scute without spine. Postpelvic and predorsal scutes absent ( Figure 3C). Anus just anterior to anal-fin origin. Snout tip rounded; snout length less than eye diameter. Mouth large, inferior, ventral to body axis, extending backward beyond posterior margin of eye. Maxilla rather long, its posterior tip pointed, just reaching (short of or slightly beyond) posterior margin of preopercle ( Figure 4). Lower jaw slender. Single row of conical teeth on each jaw and palatines. Several distinct conical teeth on vomer. Teeth patch on pterygoid. One or two rows of conical teeth on upper edges of basihyal and basibranchial. Eye large, round, covered with adipose eyelid, positioned laterally on head above horizontal through pectoral-fin insertion, visible in dorsal view. Pupil round. Orbit elliptical. Nostrils close to each other, anterior to orbit. Posterior margin of preopercle distinctly indented (Figure 4). Subopercle and opercle with smoothly rounded posterior margins. Gill membrane without serrations. Interorbital space flat, width less than eye diameter. Pseudobranchial filaments present, longest filament length less than eye diameter. Gill rakers long, slender, rough, visible from side of head when mouth opened. Single row of asperities on anterior surface of gill rakers. Isthmus muscle long, reaching anteriorly to posterior margin of gill membranes. Urohyal hidden by isthmus muscle, not visible without dissection. Gill membranes on each side joined distally, isthmus muscle mostly exposed, not covered by gill membrane. Body scales deciduous, completely lacking on specimens, except for prepelvic scutes. Head scales absent. Lateral line absent. Fins scaleless, except for broad triangular sheath of scales on caudal fin. Dorsal-fin origin posterior to vertical through base of last pelvic-fin ray, slightly posterior to middle of body. Dorsal and anal fins with three anteriormost rays unbranched and closely spaced. First dorsal-and anal-fin rays minute. Anal-fin origin just below base of tenth (eighth to tenth) dorsal-fin ray. Posterior tip of depressed anal fin not reaching caudal-fin base. Uppermost pectoral-fin ray unbranched, inserted below midline of body. Posterior tip of pectoral fin not reaching to pelvic-fin insertion. Dorsal, ventral, and posterior margins of pectoral fin nearly linear. Pelvic fin shorter than pectoral fin, insertion anterior to vertical through dorsal-fin origin. Posterior tip of depressed pelvic fin not reaching to vertical through dorsal-fin origin. Caudal fin forked, posterior tips pointed. Description. Data for holotype presented first, followed by data for paratypes in parentheses (if different). Counts and measurements expressed as percentages of SL or HL are given in Tables 1 and 2. Body laterally compressed, elongate, deepest at dorsal-fin origin. Dorsal profile of head and body slightly convex from snout tip to dorsal-fin origin, gently lowering to uppermost point of caudal-fin base. Ventral profile of head and body slightly convex from lower-jaw tip to pelvic-fin insertion, thereafter slowly rising to lowermost point of caudal-fin base. Abdomen somewhat rounded, covered with six (six or seven) spine-like scutes. Pelvic scute without spine. Postpelvic and predorsal scutes absent ( Figure 3C). Anus just anterior to anal-fin origin. Snout tip rounded; snout length less than eye diameter. Mouth large, inferior, ventral to body axis, extending backward beyond posterior margin of eye. Maxilla rather long, its posterior tip pointed, just reaching (short of or slightly beyond) posterior margin of preopercle ( Figure 4). Lower jaw slender. Single row of conical teeth on each jaw and palatines. Several distinct conical teeth on vomer. Teeth patch on pterygoid. One or two rows of conical teeth on upper edges of basihyal and basibranchial. Eye large, round, covered with adipose eyelid, positioned laterally on head above horizontal through pectoral-fin insertion, visible in dorsal view. Pupil round. Orbit elliptical. Nostrils close to each other, anterior to orbit. Posterior margin of preopercle distinctly indented (Figure 4). Subopercle and opercle with smoothly rounded posterior margins. Gill membrane without serrations. Interorbital space flat, width less than eye diameter. Pseudobranchial filaments present, longest filament length less than eye diameter. Gill rakers long, slender, rough, visible from side of head when mouth opened. Single row of asperities on anterior surface of gill rakers. Isthmus muscle Coloration of preserved specimens. Body uniformly pale yellow. Light ivory longitudinal band running from just behind upper opercular margin to caudal-fin base. Cheek and opercle silver. A few melanophores scattered on dorsum of snout. No black spots on suborbital area. A pair of distinct dark patches on parietal region, a few pigment spots on occipital area. Scale pockets on dorsum with black posterior margin. Melanophores scattered along bases of dorsal and anal fins. Double pigmented lines dorsally posterior to dorsal fin. All fins transparent, melanophores scattered along fin rays of caudal fin and anterior part of dorsal fin. Caudal fin with black upper and posterior margins.
Distribution. Stolephorus hindustanensis n. sp. is currently known only from Mumbai, northwestern coat of India (Figure 2).
Etymology. The specific name "hindustanensis" is derived from the Persian name for India (Hindustan), the type locality of the new species.
Comparisons. The new species is assignable to the genus Stolephorus, as defined by Whitehead et al. (1988) [4] and Wongratana et al. (1999) [5], having a long isthmus muscle reaching anteriorly to the posterior margin of the gill membrane, and hidden urohyal and prepelvic scutes, and postpelvic scutes absent. Stolephorus hindustanensis n. sp. most closely resembles S. ronquilloi, the two species sharing a long maxilla with the posterior tip slightly short of or just reaching the posterior border of the preopercle, indented preopercle posterior margin (Figure 4), and the dorsum with double pigmented lines behind the dorsal fin. Both species lack a predorsal scute, a spine on the pelvic scute, and black spots below the eye and lower-jaw tip ([1,4,5,14,16]; this study). Moreover, the new species differs