The Influence of Volcanism, Soils, and Climate in the Endemicity Levels of Asteraceae in the Arequipa Region (Southern Peru)

Abstract

We present the diversity of Asteraceae in the Arequipa Region of southern Peru, an area strongly influenced by volcanism, which has given rise to different soil types and has determined a very wide bioclimatic and vegetational zonation. We present the distribution of Asteraceae endemisms of Peru and Arequipa, and of the dry puna. For this purpose, we have used the bioclimatic methodology of Rivas-Martínez, the characteristic soils of each collection point, and the distance of the collection localities from the volcanoes. In the Arequipa Region, we found 232 species of Asteraceae, of which 49 are endemic to Peru or to the dry puna and 7 are endemic to the studied area. Of these endemics, 10 are thermotropical, 1 is mesotropical, 3 are supratropical, and 3 are orotropical bioindicators, being mainly distributed in two large groups of soils: sandy and saline or gypsiferous soils, mostly located within the thermotropical belt of the coastal desert, and andosols and cambisols distributed from the thermotropical to the cryorotropical belts of the Andes. The greatest number of endemics and semi-endemics are found in the vicinity of the arc formed by the Misti, Chachani and Pichu-Pichu volcanoes.

1. Introduction

The Asteraceae family, together with the Orchidaceae, Poaceae, and Piperaceae, is one of the most diverse families in Peru [1]. The most recent list of the New World Flora [2] reported 1474 species of Asteraceae, although various taxonomic studies led to a reduction to 1244 between synonymies and species absent from the Peruvian territory [3,4].

Perhaps the first author to synthetically study the Asteraceae in southern Peru was Weddell [5], including genera such as Mutisia L.f., Perezia Lag., Plazia Ruiz & Pav. or Werneria Kunth (=Rockhausenia D.J.N. Hind), based on the work of post-Linnaean authors such as Linnaeus filius, Ruiz and Pavón, Humboldt et al., or Lessing [6,7,8,9]. Without forgetting the data of Weberbauer [10] in southern Peru, with the ecological behavior of Ambrosia, Diplostephium Kunth, Grindelia Willd., Lepidophyllum Cass. (=Parastrephia Nutt.), Onoseris Willd., Proustia Lag. Or Senecio L., we have added numerous contributions restricted to certain groups or genera, such as Chersodoma Phil. [11], Mutisia [12,13], Gochnatia Kunth [14], Plazia [15], Senecio [16,17,18,19]), Werneria (=Rockhausenia) [20,21], Xenophyllum V.A. Funk (=Werneria) [21,22,23], and to floristic and vegetational studies [24].

The Arequipa Region is located in southern Peru, between the coordinates 15°11′45.72″ S/73°27′54.70″ W and 16°47′08.93″ S/70°03′51.28″ W, longitudinally, and 14°37′51.08″ S/71°59′04.75″ W and 16°35′21.08″ S/72°47′05.95″ W, transversely, and presents six large areas with habitat types of different climatic characters: (a) coastal desert hills (‘lomas’) with ephemeral vegetation and isolated Cactaceae (0–1000 m a.s.l.), (b) inter-desert barrier as a large plain with Quaternary fluvial and aeolian sedimentation only with the vegetation of the streams (1000–2000 m a.s.l.), (c) western Andean slopes with Cactaceae and shrub communities (2000–3100 m a.s.l.), (d) western Andean slops with mesophytic shrubs (3100–3800 m a.s.l.), (e) volcanic reliefs with deep soils of the dry highlands with shrubs and grasslands (‘dry puna’), the humid highlands with a predominance of grasslands (‘humid puna’) (3800–4800 m a.s.l.), and (f) the coldest areas with cryogenic processes with small grasslands, usually above 4800 m a.s.l. [25]. These landscape units reach their greatest extensions in the Arequipa Region with respect to others in Peru, with volcanic soils and morphology, making it a model area for establishing ecological relationships in various plant families.

Volcanoes have undoubtedly marked the landscape of Arequipa with super-eruptions dating back 490 million years (Ordovician) [26], Pleistocene stratovolcanoes (2.59 m.y. BP) [27], such as the Chachani complex [28]), with relatively modern eruptions, such as those of Misti in the 15th century [27], Huaynaputina, in the 17th century (Moquegua Region) [29] or Sabancaya at present (Figure 1). The Pichu-Pichu volcano represents an older geomorphological pattern, as it is known to have been active 6.7 m.y. ago (Miocene) and part of it collapsed 1 m.y. ago [30,31].

Several studies have revealed the relationship between plant diversity, climatic factors, soil types, and volcanic activity in different parts of the world [32,33,34,35]. Dimopoulos et al. [32] indicated that areas more distant from the most modern volcanism have the highest floristic diversity, while materials derived from the most modern volcanism have a low diversity and tend to be terophytes or bisannuals. Schwarzer et al. [33] studied the distribution and dispersal of plants due to the Huaynaputina super-eruption, concluding that some species had dispersed from very distant Andean areas from Argentina or Chile to southern Peru with the substrate originated by the eruption having a strong influence. Ghermandi et al. [34] comparing plant composition before and after a volcanic eruption in Patagonia observed that plant cover is higher in areas with volcanic ash than in areas without volcanic ash, and that ash deposition removes exotic terophytes but increases the presence of geophytes. Martín Osorio et al. [35] studied the colonising vegetation in a recent eruption on the Canary Island of Tenerife, observing a high number of endemic species in the lower vegetation belts.

The aim of this work was to obtain an updated catalogue of the species of Asteraceae in the Arequipa Region, establishing the distribution patterns of its endemisms and semi-endemisms in relation to bioclimatology, soil types, and volcanism in order to identify future conservation areas within the territory studied.

2. Materials and Methods

2.1. Studying and Arranging Herbarium Vouchers

To know the number of Asteraceae species growing in the Arequipa Region, 2206 herbarium sheets from the CUZ, F, HBG, HUSA, K, MA, MO, NY, P, US, and USM herbaria (acronyms following Thiers, continuously updated [36]) were studied. For each, the locality, collector and collection number, month, year, altitude, and coordinates were detailed (Supplementary Table S1). The Asteraceae of Arequipa with the distribution in other Peruvian regions (Supplementary Table S2) were extracted from the Supplementary Table S1 in order to discover which are the endemisms and semi-endemisms of the territory studied.

Endemisms are species that inhabit within the borders of the Peruvian territory or the Arequipa Region, while semi-endemisms are species distributed throughout the regions of Ica, Ayacucho, Arequipa, Moquegua, and Tacna in Peru, even though they extend to Bolivia, Chile and Argentina; they are species that are spread throughout the driest part of the Andes, from the Ica Region to the highlands of Bolivia, Chile and Argentina (Xerophytic Punenian biogeographic province) according to the biogeographical sectorisation by Rivas-Martínez et al. [37].

Appendix A,

Table A1. Table with the values taken to obtain the PCA of Figure 2, bioclimatic diagnosis, volcanoes closest to the localities studied, and percentage of soil types per pixel of SoilGrids database in a locality (Synthesis of the Supplementary Table S3).

Locality Number	Locality of Table S1	Endemisms and Semi-Endemisms of Arequipa Region	Regional Distribution in Peru	Locality of Arequipa Region	Bioclimatic Diagnosis	H	It	P	DIST	And	Are	Reg	Lep	Cal	Cam	Luv	Flu	Sch	Gyp	Kst	Pha	Ver	Volcano
1	17	Ambrosia pannosa	AR	Tingo	Mes sem	2224	428	134	12.72	0	0	26	14	19	11	0	6	0	0	0	0	0	Misti
2	79	Heiseria irmscheriana	AR	Mejia	The ulha	30	641	3	81.03	0	11	19	12	0	9	10	0	0	0	0	0	0	Cerro Nicholson
3	82	Helogyne hutchisonii	AR	Atico	The ha	57	511	19	92.56	0	30	21	16	5	5	0	0	0	0	0	0	0	Sara-Sara
4	101	Lomanthus mollendoensis	AR	Atiquipa	The sem	500	532	111	98.05	0	8	15	20	0	15	12	0	0	0	0	0	0	Sara-Sara
5	130	Paquirea lanceolata	AR	Orcopampa	Sup suh	3790	193	600	14.32	6	0	14	16	0	34	0	7	0	0	0	0	0	Andahua-Orcopampa
6	182	Senecio smithianus	AR	Atiquipa	The sem	275	530	111	106.16	0	11	19	20	0	9	9	0	0	0	0	0	0	Sara-Sara
7	214	Wedelia hoffmanniana	AR	Mejia	The ulha	444	552	0	138.48	0	11	20	16	13	0	0	0	11	0	0	0	0	Sara-Sara
8	524	Aldama dilloniorum	AR MO TA	Cerro Verde	Mes sem	2600	438	116	20	0	9	26	22	22	0	0	5	0	0	0	0	0	Misti
9	525	Idem	AR MO TA	Yura	Mes sem	3100	346	188	8.17	17	0	21	10	0	15	11	0	0	0	0	0	0	Chachani
10	526	Idem	AR MO TA	Chachani	Mes sem	2800	374	134	4	10	0	14	12	0	22	7	0	0	0	0	0	0	Chachani
11	527	Idem	AR MO TA	Ojuli	Sup sem	2500	243	179	7.38	0	10	19	18	18	11	0	0	0	0	0	0	0	Misti
12	1092	Ambrosia dentata	AR IC	Jahuay	The ulha	300	503	0	146.61	0	11	23	13	9	0	0	0	13	0	0	0	0	Sara-Sara
13	1094	Idem	AR IC	Atico	The ha	277	517	19	91.82	0	25	18	27	7	0	0	6	0	0	0	0	0	Sara-Sara
14	1100	Idem	AR IC	Chala	The sem	430	531	114	88.98	0	15	22	15	7	0	0	0	0	6	0	0	0	Sara-Sara
15	1101	Idem	AR IC	Los Cerrillos	The ulha	800	532	0	149.12	0	13	17	14	16	0	0	10	0	0	0	0	0	Sara-Sara
16	1103	Idem	AR IC	Atiquipa	The ar	500	530	97	102.27	0	11	16	22	0	10	14	0	0	0	0	0	0	Sara-Sara
17	19	Aphyllocladus denticulatus	AR MO TA	Huancarqui	Mes ar	2600	417	37	27.19	0	10	16	18	11	10	0	0	0	0	0	0	0	Huambo
18	653	Idem	AR MO TA	Polobaya	Mes sem	2900	407	122	47.57	0	8	27	9	16	0	0	0	11	0	0	0	0	Huaynaputina
19	654	Idem	AR MO TA	Quebrada Escalerilla	Mes ar	2754	247	76	13.9	0	0	23	23	11	16	0	4	0	0	0	0	0	Ubinas
20	655	Idem	AR MO TA	Socabaya	Mes sem	2160	475	141	13.21	0	10	24	16	20	7	0	0	0	0	0	0	0	Misti
21	656	Idem	AR MO TA	Yura	Mes sem	2200	426	188	11.89	16	8	21	13	0	9	0	0	0	0	0	0	0	Chachani
22	1177	Idem	AR MO TA	Atico	The ha	1274	521	19	91.27	0	0	26	28	0	7	0	6	20	0	0	0	0	Sara-Sara
23	1178	Idem	AR MO TA	Quicacha	Mes sem	2673	433	226	36.98	0	0	28	21	10	8	0	8	0	0	0	0	0	Sara-Sara
24	1716	Idem	AR MO TA	Puyca	Cry hum	3659	42	1009	53.62	0	0	9	16	0	18	0	0	0	0	11	10	0	Cerro Auquihuato
25	1717	Idem	AR MO TA	Pampamarca	Oro hum	3300	138	993	31.09	0	0	0	11	0	21	12	0	0	0	8	14	0	Cerro Auquihuato
26	1488	Aristeguietia cursonii	AR MO TA	Salamanca	Sup hum	3600	297	1001	11.29	0	0	9	12	7	27	11	0	0	0	0	0	0	Coropuna
27	21	Idem	AR MO TA	Cotahuasi	Oro hhum	4200	90	1603	14.99	0	0	10	22	4	25	13	0	0	0	0	0	0	Nevados Firura
28	321	Diplostephium meyenii	AR AY MO TA	Arequipa	Mes sem	2363	471	141	16	0	14	16	14	15	8	0	0	0	0	0	0	0	Misti
29	324	Idem	AR AY MO TA	Chiguata	Oro dry	4000	85	324	2.75	12	0	15	11	0	32	0	6	0	0	0	0	0	Pichu-Pichu
30	330	Idem	AR AY MO TA	Misti	Sup dry	3640	235	324	2.15	14	0	11	11	0	23	7	0	0	0	0	0	0	Misti
31	332	Idem	AR AY MO TA	Chachani	Oro dry	4000	72	329	2.27	10	0	15	14	0	20	8	0	0	0	0	0	0	Chachani
32	337	Idem	AR AY MO TA	Pampa de Arrieros	Sup dry	3700	209	442	14.49	13	0	11	9	0	26	11	0	0	0	0	0	0	Chachani
33	338	Idem	AR AY MO TA	Rio de Lomas	Sup sem	2850	192	179	6.16	0	0	17	20	13	14	7	0	0	0	0	0	0	Misti
34	339	Idem	AR AY MO TA	Yura	Mes sem	2700	383	234	10	15	0	16	18	10	11	0	0	0	0	0	0	0	Chachani
35	341	Idem	AR AY MO TA	Yura, Chingana	Mes sem	3000	337	134	7	21	0	12	13	0	10	13	0	0	0	0	0	0	Chachani
36	1017	Idem	AR AY MO TA	Cahuacho	Sup dry	3380	316	381	12.54	9	11	14	11	0	0	11	0	0	0	0	0	0	Sara-Sara
37	1477	Idem	AR AY MO TA	Condesuyos	Cry shu	4300	44	733	11.43	0	0	13	26	6	27	0	5	0	0	0	0	0	Nevados Firura
38	1478	Idem	AR AY MO TA	Chuqui-bamba	Mes ar	2300	404	45	21.23	0	0	17	24	9	14	9	0	0	0	0	0	0	Coropuna
39	1688	Idem	AR AY MO TA	Tauría	Oro hum	4000	144	926	26.46	14	0	11	12	0	28	10	0	0	0	0	0	0	Sara-Sara
40	57	Idem	AR AY MO TA	Polobaya-Pocsi	Mes sem	3100	352	202	19.78	15	11	11	10	0	0	16	0	0	0	0	0	0	Misti
41	659	Gochnatia arequipensis	AR AY MO TA	Arequipa	Mes sem	2755	398	122	17.67	9	10	22	21	11	0	0	0	0	0	0	0	0	Pichu-Pichu
42	662	Idem	AR AY MO TA	Arequipa, aeropuerto	Mes sem	2600	426	134	13.74	0	0	26	15	19	11	5	0	0	0	0	0	0	Chachani
43	663	Idem	AR AY MO TA	Cerro Verde	Mes sem	2600	432	116	26.99	0	10	24	20	20	7	0	0	0	0	0	0	0	Cerro Nicholson
44	665	Idem	AR AY MO TA	Chiguata	Mes sem	3000	370	251	3.29	10	0	15	9	0	29	0	12	0	0	0	0	0	Pichu-Pichu
45	668	Idem	AR AY MO TA	Misti	Sup dry	3624	235	324	2.6	11	0	12	13	0	21	13	0	0	0	0	0	0	Misti
46	669	Idem	AR AY MO TA	Mollebaya	Sup sem	2400	245	141	11.61	8	17	21	0	8	10	0	0	0	0	0	0	0	Misti
47	670	Idem	AR AY MO TA	Chachani	Mes dry	3050	342	329	5.16	10	0	12	19	0	17	8	0	0	0	0	0	0	Chachani
48	672	Idem	AR AY MO TA	Quebrada Lajas	Mes sem	2300	462	152	12.41	0	6	31	16	18	0	0	7	0	0	0	0	0	Chachani
49	673	Idem	AR AY MO TA	Socabaya	Mes sem	2344	460	141	22.04	0	9	18	16	19	7	0	0	0	0	0	0	0	Misti
50	674	Idem	AR AY MO TA	Queque	Mes sem	2300	459	166	14.7	0	0	26	18	18	9	0	6	0	0	0	0	0	Cerro Nicholson
51	1179	Idem	AR AY MO TA	Atiquipa	The sem	350	551	105	103.76	0	13	15	21	0	12	12	0	0	0	0	0	0	Sara-Sara
52	1389	Idem	AR AY MO TA	Cabanaconde	Sup dry	3200	306	496	19.92	8	0	13	14	0	13	11	0	0	0	0	0	0	Sabancaya
53	1718	Idem	AR AY MO TA	Cotahuasi	Mes sem	2700	341	144	26.64	0	0	10	17	0	23	9	0	0	0	0	7	0	Nevados Firura
54	1057	Helogyne apaloidea	AR MO	Caravelí	Mes sem	2626	490	207	37.93	0	8	27	12	0	0	6	0	0	0	0	0	0	Sara-Sara
55	1058	Idem	AR MO	Atico	The ha	50	590	19	87.64	0	0	32	30	0	13	0	5	11	0	0	0	0	Sara-Sara
56	99	Lomanthus icaensis	AR IC	Acarí	The ar	650	535	37	126.44	0	16	18	11	13	0	0	0	9	0	0	0	0	Sara-Sara
57	1244	Idem	AR IC	Los Cerrillos	The ar	865	532	85	143.65	0	0	19	15	14	0	0	13	12	0	0	0	0	Sara-Sara
58	1254	Lomanthus mollendoensis	AR	Toro	The sem	350	557	109	103.56	0	10	23	21	0	8	7	0	0	0	0	0	0	Sara-Sara
59	1255	Idem	AR	Atiquipa	The sem	200	532	110	104.11	0	11	16	22	0	10	14	0	0	0	0	0	0	Sara-Sara
60	1662	Idem	AR	Islay	The ulha	10	490	3	80.48	0	0	26	20	0	10	10	4	0	0	0	0	0	Cerro Nicholson
61	1664	Idem	AR	Rio Tambo	The ar	680	578	50	94.07	0	27	12	29	6	0	0	0	0	9	0	0	0	Huaynaputina
62	1666	Idem	AR	Mollendo	The ar	928	517	62	73.44	0	0	31	33	0	10	6	0	11	0	0	0	0	Cerro Nicholson
63	102	Lomanthus okopanus	AR IC	Lomas de Cháparra	The sem	500	611	143	76.15	0	0	39	21	0	7	0	10	13	0	0	0	0	Sara-Sara
64	1258	Idem	AR IC	Lomas de Ocopa	The sem	700	532	110	100.12	0	11	19	20	0	9	9	0	0	0	0	0	0	Sara-Sara
65	105	Lophopappus cuneatus	AR TA	Arequipa	Mes sem	2447	386	123	22.19	0	14	16	14	15	8	0	0	0	0	0	0	0	Pichu-Pichu
66	1393	Idem	AR TA	Caylloma	Oro suh	3200	119	750	25.41	0	0	11	20	0	20	14	0	0	0	5	0	0	Sabancaya
67	1499	Idem	AR TA	Chuqui-bamba	Oro suh	3900	160	706	15.21	9	13	14	13	0	18	0	0	0	0	0	0	0	Coropuna
68	1394	Lophopappus foliosus	AR MO	Cabanaconde	Sup suh	3700	232	693	12.95	0	0	8	11	0	17	14	0	0	0	12	0	0	Sabancaya
69	106	Idem	AR MO	Chivay	Oro suh	4000	83	688	36.74	0	0	11	14	0	25	10	0	0	0	9	0	0	Sabancaya
70	1401	Mutisia arequipensis	AR AY	Caylloma	Oro suh	3200	119	750	25.28	5	0	8	19	23	9	0	0	0	0	0	0	0	Sabancaya
71	1727	Idem	AR AY	Cotahuasi	Oro hum	4284	72	1202	10.8	0	0	9	24	5	26	9	0	0	0	0	0	0	Nevados Firura
72	1728	Idem	AR AY	Puyca	Oro hum	3600	82	1030	13.54	0	0	0	13	0	17	10	0	0	0	11	10	0	Nevados Firura
73	1730	Idem	AR AY	Huaynacotas	Oro hum	3931	144	1238	20.89	0	0	0	15	0	23	16	0	0	0	0	8	6	Nevados Firura
74	1731	Idem	AR AY	Tauría	Oro hum	4200	110	1434	22.71	7	0	11	13	0	36	8	0	0	0	0	0	0	Solimana
75	1732	Idem	AR AY	Toro	Oro hum	4400	61	1487	3.67	6	0	7	17	0	40	0	10	0	0	0	0	0	Solimana
76	1770	Idem	AR AY	Sayla	Sup suh	3600	238	755	19.63	7	0	0	9	0	25	22	0	0	0	0	6	0	Sara-Sara
77	706	Mutisia orbignyana	AR MO TA	Arequipa	Sup sem	3156	312	264	1.9	16	0	15	0	12	14	11	0	0	0	0	0	0	Misti
78	709	Idem	AR MO TA	Arequipa-Cusco	Sup sem	3375	264	261	13.15	0	0	16	15	11	20	9	0	0	0	0	0	0	Chachani
79	1299	Idem	AR MO TA	Pampacolca	Oro suh	3900	148	600	6.82	0	0	12	11	0	26	15	6	0	0	0	0	0	Coropuna
80	1300	Idem	AR MO TA	Andahua	Sup suh	3611	238	668	8.6	11	0	9	15	0	24	0	7	0	0	0	0	0	Andahua-Orcopampa
81	1303	Idem	AR MO TA	Castilla	Sup suh	3600	170	754	29.38	0	0	10	17	0	24	9	0	0	0	8	0	0	Andahua-Orcopampa
82	1402	Idem	AR MO TA	Chivay	Oro suh	4400	104	574	34.14	0	0	11	27	0	18	7	9	0	0	0	0	0	Sabancaya
83	1403	Idem	AR MO TA	Puquina	Sup suh	3600	286	575	20.91	11	0	15	13	0	16	7	0	0	0	0	0	0	Huambo
84	1404	Idem	AR MO TA	Caylloma	Sup suh	3639	214	574	30.08	0	0	14	9	0	19	7	0	0	0	0	0	7	Sabancaya
85	1406	Idem	AR MO TA	Cabanaconde	Sup suh	3700	199	754	15.55	9	0	8	8	0	26	10	0	0	0	0	0	0	Huambo
86	1407	Idem	AR MO TA	Huambo	Sup suh	3800	187	600	1.1	9	0	15	12	0	34	7	0	0	0	0	0	0	Huambo
87	1502	Idem	AR MO TA	Condesuyos	Sup suh	3800	178	533	13.82	12	0	19	8	0	16	9	0	0	0	0	0	0	Coropuna
88	122	Onoseris minima	AR MO	Arequipa	Oro dry	4436	89	352	0.83	7	0	16	17	0	27	9	0	0	0	0	0	0	Misti
89	124	Ophryosporus bipinnatifidus	AR MO	Cachendo	The ar	400	597	48	110.8	0	9	13	0	0	0	9	0	0	0	0	9	11	Huaynaputina
90	126	Ophryosporus hoppii	AR MO TA	Atiquipa	The sem	300	502	113	105.23	0	10	19	21	0	12	12	0	0	0	0	0	0	Sara-Sara
91	459	Idem	AR MO TA	Arequipa	Mes sem	2700	398	122	2.53	11	0	9	10	0	31	8	0	0	0	0	0	0	Pichu-Pichu
92	958	Idem	AR MO TA	Camaná	The ar	600	611	44	106.59	0	15	10	29	11	0	0	0	11	0	0	0	0	Huambo
93	960	Idem	AR MO TA	Ocoña	The ar	205	589	52	90.61	0	15	25	15	7	10	0	0	0	0	0	0	0	Coropuna
94	1287	Idem	AR MO TA	Aplao	The ar	657	522	50	46.47	0	12	20	0	12	10	0	22	0	0	0	0	0	Huambo
95	1552	Idem	AR MO TA	Mollendo	The ha	230	507	26	69.17	0	22	16	25	9	0	0	0	0	6	0	0	0	Cerro Nicholson
96	142	Pluchea absinthioides	AR	Arequipa	Mes sem	2287	476	148	14.86	8	0	22	20	10	11	0	0	0	0	0	0	0	Misti
97	745	Idem	AR	Tiabaya	The sem	2100	504	110	15.87	0	35	23	0	7	0	0	9	0	0	0	4	0	Misti
98	144	Polyachyrus annuus	AR IC MO TA	Atico	The ar	50	630	50	106.39	0	22	20	26	8	5	0	0	0	0	0	0	0	Coropuna
99	991	Idem	AR IC MO TA	Mollendo	The ar	650	534	47	63.67	0	0	24	40	0	0	0	4	23	0	0	0	4	Cerro Nicholson
100	992	Idem	AR IC MO TA	Camaná	The ar	300	611	44	96.2	0	15	10	29	11	0	0	0	11	0	0	0	0	Huambo
101	994	Idem	AR IC MO TA	Arantas	The ar	680	614	47	81.38	0	0	37	29	0	15	7	8	0	0	0	0	0	Cerro Nicholson
102	1214	Idem	AR IC MO TA	Chala	The sem	50	541	143	88.11	0	0	25	25	0	8	11	0	0	0	0	0	9	Sara-Sara
103	1645	Idem	AR IC MO TA	Mejía	The ar	200	576	46	89.48	0	18	11	31	7	7	0	0	0	0	0	0	0	Misti
104	1649	Idem	AR IC MO TA	Islay	The ar	181	594	47	78.22	0	15	10	30	0	7	0	0	11	0	0	0	0	Cerro Nicholson
105	806	Senecio calcicola	AR IC	Chucarapi	The ar	750	578	53	104.47	0	21	0	26	8	0	0	0	8	7	0	0	0	Huaynaputina
106	807	Idem	AR IC	Quebrada Guerreros	Mes sem	2766	372	116	22.05	0	8	19	20	16	0	0	11	0	0	0	0	0	Misti
107	1004	Idem	AR IC	Arantas	The ar	980	534	47	81.92	0	0	38	28	0	13	0	8	7	0	0	0	0	Cerro Nicholson
108	1668	Idem	AR IC	Mollendo	The ar	560	526	53	77.98	0	12	17	14	0	0	7	6	0	0	0	0	0	Cerro Nicholson
109	1673	Idem	AR IC	Islay	The ar	17	597	48	108.79	0	9	11	0	0	0	10	10	0	0	0	0	11	Huaynaputina
110	1675	Idem	AR IC	Islay	The ar	250	596	55	78.58	0	15	11	35	7	0	0	0	7	0	0	0	0	Cerro Nicholson
111	1676	Idem	AR IC	Tintayami	The ar	700	566	51	76.69	0	24	12	24	9	0	0	0	6	0	0	0	0	Cerro Nicholson
112	808	Senecio crassilodix	AR AY MO TA	Arequipa	Oro dry	4200	110	407	27.11	9	0	14	21	6	30	0	0	0	0	0	0	0	Misti
113	809	Idem	AR AY MO TA	Chiguata	Oro dry	4321	94	408	24.7	0	0	8	0	13	22	13	7	0	0	0	0	0	Ubinas
114	810	Idem	AR AY MO TA	Chachani	Oro dry	4200	72	320	2.51	10	0	14	12	0	22	7	0	0	0	0	0	0	Chachani
115	164	Idem	AR AY MO TA	Orcopampa	Oro suh	4200	97	619	16.05	0	0	8	17	0	17	10	0	0	0	0	8	0	Andahua-Orcopampa
116	174	Senecio neoviscosus	AR MO	Baños de Jesús	Sup sem	2800	241	207	6.99	7	0	23	16	15	9	0	0	0	0	0	0	0	Misti
117	180	Senecioscorzonerifolius	AR MO TA	Arequipa-Cusco	Sup sem	3850	268	236	14.53	0	8	13	12	13	22	0	0	0	0	0	0	0	Chachani
118	187	Senecio yurensis	AR MO	Baños de Jesús	Sup sem	2700	244	187	9.4	0	0	15	16	17	15	7	0	0	0	0	0	0	Misti
119	912	Idem	AR MO	Arequipa	Sup sem	3800	229	196	6.46	11	0	16	18	15	9	0	0	0	0	0	0	0	Misti
120	914	Idem	AR MO	Arequipa, aeropuerto	Mes sem	2900	423	204	11.14	0	0	27	14	14	9	5	0	0	0	0	0	0	Chachani
121	919	Idem	AR MO	Cerro San Ignacio	Mes sem	2500	431	117	17.59	0	9	25	24	16	6	0	0	0	0	0	0	0	Misti
122	920	Idem	AR MO	Cerro Verde	Mes sem	2600	446	107	25.05	0	10	27	16	19	0	0	0	0	0	0	0	0	Misti
123	922	Idem	AR MO	Chiguata	Mes sem	2100	370	264	0.6	0	0	26	16	6	22	8	0	0	0	0	0	0	Pichu-Pichu
124	926	Idem	AR MO	Chili	Mes sem	2500	450	103	18.43	0	0	33	14	0	10	8	15	0	0	0	0	0	Cerro Nicholson
125	927	Idem	AR MO	Lluta	Sup dry	3884	261	518	10.12	7	0	15	13	0	26	9	0	0	0	0	0	0	Chachani
126	928	Idem	AR MO	Misti	Sup dry	3831	190	398	8.77	8	0	7	19	0	20	11	0	0	0	0	0	0	Misti
127	929	Idem	AR MO	Chachani	Sup dry	3600	277	320	2.45	10	0	19	17	0	20	6	0	0	0	0	0	0	Chachani
128	931	Idem	AR MO	Polobaya-Chapi	Mes ar	2540	456	100	42.31	0	0	22	14	23	7	0	9	0	0	0	0	0	Huaynaputina
129	932	Idem	AR MO	Quebrada Honda	Mes sem	2600	471	122	13.63	10	0	14	15	0	27	5	0	0	0	0	0	0	Pichu-Pichu
130	933	Idem	AR MO	Tiabaya	Mes sem	2430	444	110	21.31	0	29	23	0	6	0	5	12	0	0	0	0	0	Misti
131	936	Idem	AR MO	Yura	Mes sem	2985	346	273	7.92	19	0	14	11	0	15	13	0	0	0	0	0	0	Chachani
132	945	Idem	AR MO	Yura-Huanca	Mes sem	2700	418	236	16.42	0	7	18	17	11	13	0	0	0	0	0	0	0	Cerro Nicholson
133	946	Idem	AR MO	Yura-Huanca	Mes sem	2500	409	280	10.61	0	8	28	18	8	11	0	0	0	0	0	0	0	Chachani
134	1005	Idem	AR MO	Tambillo	The ha	1199	542	26	71.35	0	10	19	19	13	0	0	0	12	0	0	0	0	Huambo
135	1459	Idem	AR MO	San Antonio de Chuca	Oro suh	4442	60	657	37.26	0	0	12	19	17	29	0	4	0	0	0	0	0	Huarancante
136	1756	Idem	AR MO	Cotahuasi	Mes sem	2600	341	144	10.19	7	0	9	16	0	33	10	0	0	0	0	0	0	Solimana
137	227	Werneria esquilachensis	AR MO TA	Pichu-Pichu	Oro dry	4926	142	324	1.03	8	0	16	14	0	20	8	0	0	0	0	0	0	Pichu-Pichu
138	951	Idem	AR MO TA	Tunel El Cimbral	Oro dry	4279	82	393	3.03	15	0	19	14	6	20	0	0	0	0	0	0	0	Pichu-Pichu

Symbols: AR—Arequipa, AY—Ayacucho, IC—Ica, MO—Moquegua, TA—Tacna. Bioclimatic diagnosis and bioclimatic belts: The—Thermotropical, Mes—Mesotropical, Sup—Supratropical, Oro—Orotropical, Cry—Cryorotropical. Ombrotypes: ulha—Ultrahyperarid, ha—Hyperarid, ar—Arid, sem—Semiarid, dry—Dry, suh—Subhumid, hum—Humid, hhum—Hyperhumid, H—Altitude (m), It—Thermicity Index, P—Annual precipiation (mm). DIST—Smaller distance from the volcanoes (Km). Soil types: And—Andosols, Are—Arenosols, Reg—Regosols, Lep—Leptosols, Cal—Calcisols, Cam—Cambisols, Luv—Luvisols, Flu—Fluvisols, Sch—Solonchaks, Gyp—Gypsisols, Kst—Kastanozems, Pha—Phaeozems, Ver—Vertisols.

are the species of non-repeated localities of the database (Supplementary Table S1) with decimal coordinates and is a synthesis of Supplementary Table S3. Decimal coordinates were also used to generate the distribution maps of the Figures 1, 8, and 9 with the Quantum Geographic Information System (QGIS) 3.0.1 [38].

2.2. Bioclimatic Characterization of Plants

To bioclimatically characterise the locality of each herborised specimen, we used the Rivas-Martínez model of bioclimatic belts [39]. Bioclimatic belts are based on thermicity index (It) ranges and bioindicators, which are plants and associations of vegetation. The thermicity index is a mathematical expression containing different temperature values in degrees centigrade: It = (T + M + m) 10 [T: Average annual temperature, M: Average maximum temperature in the coldest month, m: Average minimum temperature of the coldest month]. At present, we are able to distinguish six bioclimatic belts or thermotypes throughout Peru (Figure 2, [40]): Infratropical (It > 690), thermotropical (It = 490 to 690), mesotropical (It = 320 to 490), supratropical (It = 160 to 320), orotropical (It = 50 to 160), and cryorotropical (It = < 50). These belts are nuanced by rainfall intervals (annual P in mm) or ombrotypes, so we can observe a very humid thermotropical belt in the Amazon but be very dry in Southern Peru. We can distinguish nine types of precipitation intervals in the country: Ultrahyperarid (P < 5), hyperarid (5 to 30), arid (31 to 100), semiarid (101 to 300), dry (301 to 500), subhumid (501 to 900), humid (901 to 1500), hyperhumid (1501 to 2500), and ultrahyperhumid (>2500). In Arequipa, the bioclimate fluctuates from thermotropical ultrahyperarid to cryorotropical humid [41].

Meteorological data, with a time frame of 30 years, were taken from METEOBLUE [42], establishing comparisons in some cases with the results of the CHELSA database [43]. These computer tools make it possible to obtain meteorological values and climate diagrams for any coordinate, which increases the accuracy of the relationship between a species and certain bioclimatic indices and parameters.

2.3. Plants, Soils and Volcanism

To observe the influence of soil types on the flora, we used SoilGrids database [44] by matching the coordinates of the localities where specimens were collected with those of the corresponding pixel which indicates the percentage of soil types. According to IUSS Working Group WRB [45], we have distinguished 13 soil types in the Arequipa Region (Appendix A, Table A1; Supplementary Table S3): Andosols: volcanic soils par excellence, formed on ashes, volcanic glasses, or from pyroclasts (they are found in regions with active or recent volcanism, that is, in the vicinity of volcanic cones); arenosols: sandy soils; regosols: soils with no significant profile development; leptosols: shallow or extremely gravelly soils; calcisols: soils with accumulation of calcium carbonate; cambisols: moderately developed soils; luvisols: soils with a clay-enriched subsoil, with a high base status and high-activity clay; fluvisols: floodplains and tidal marshes; solonchaks: soils with salt enrichment upon evaporation; gypsisols: soils with accumulation of gypsum; kastanozems: soils of dry climate, with accumulation of organic matter phaeozems: soils of more humid climate, with accumulation of organic matter; and vertisols: soils influenced by water, alternating wet-dry conditions and rich in swelling clays.

In addition, to test the possible tendency of flora distribution versus volcanism, we calculated the distance between the localities of the specimens and the base of the Arequipa volcanoes (DIST) (Appendix A, Table A1; Supplementary Table S3) using the database of the Global Volcanism Program of Smithsonian Institution [46]. From this database, it is possible to obtain a kml file visible using the Google-Earth portal [47]. For this purpose, localities between 0 and 50 km were separated from localities between 50 and 150 km, since 50 km is the approximate distance between the coastline and the beginning of the western Andean slope.

2.4. Statistical Analysis

To observe the tendency of the distribution of 138 collected specimens in relation to their altitude (H), climatic variables and indices (T, M, m, It, P), distance to the nearest volcanoes (DIST), and percentages of the soils found in the pixel of a given locality, we used a principal component analysis (PCA) based on a matrix with the numerical data of the Appendix A, Table A1, or Supplementary Table S3. Eingenvectors indicate how the variables correlate with the location of the specimens. To see how the different variables are correlated, a correlation matrix was carried out using Pearson’s parametric test. These statistical analyses were run with the PAST 4.07b software [48].

3. Results

3.1. Diversity of Asteraceae in the Arequipa Region

Among the 2206 herbarium sheets studied (Supplementary Table S1), 232 species belonging to 82 genera of the Asteraceae family from the Arequipa Region were extracted (Supplementary Table S2), of which 49 are Peruvian endemics or semi-endemics of the Xerophytic Punenian biogeographic province: Ageratina lobulifera (B.L.Rob.) R.M.King and H. Rob., Aldama dilloniorum (A.J.Moore and H. Rob.) E.E.Schill. and Panero, A. peruviana (A. Gray) E.E.Schill. and Panero, Ambrosia dentata (Cabrera) M. O. Dillon, *A. pannosa W.W.Payne, Aristeguietia ballii (Oliv.) R.M.King and H. Rob., A. cursonii (B.L.Rob.) R.M.King and H. Rob., Baccharis scandens (Ruiz and Pav.) Pers., Chersodoma juanisernii (Cuatrec.) Cuatrec., Chionopappus benthamii S. F. Blake, Erigeron incaicus Solbrig, E. leptorhizon DC., Gochnatia arequipensis Sandwith, *Heiseria irmscheriana (Bruns) Mesfin, *Helogyne hutchisonii R.M.King and H. Rob., Heterosperma ferreyrii H. Rob., Lomanthus arnaldii (Cabrera) B. Nord. and Pelser, L. icaensis (H.Beltrán and A. Galán) B. Nord., L. lomincola (Cabrera) B. Nord. and Pelser, *L. mollendoensis (Cabrera) B. Nord., L. okopanus (Cabrera) B. Nord., L. subcandidus (A. Gray) B. Nord., L. tovarii (Cabrera) B. Nord. & Pelser, Munnozia lyrata (A. Gray) H. Rob. and Brettell, Mutisia arequipensis Cabrera, Nordenstamia longistyla (Greenm. and Cuatrec.) B. Nord., Onoseris minima Domke, O. odorata (D. Don) Hook and Arn., Ophryosporus bipinnatifidus B.L.Rob., O. pubescens (Smith) R.M.King and H. Rob., *Paquirea lanceolata (H.Beltrán and Ferreyra) Panero and S. Freire, Philoglossa peruviana DC., Senecio acarinus Cabrera, S. beltranii P. Gonzáles and Montesinos, S. chachaniensis Cuatrec., S. crassilodix Cuatrec., S. flaccidifolius Wedd., S. gamolepis Cabrera, S. hebetatus Wedd., S. neoviscosus Cuatrec., *S. smithianus Cabrera, S. yurensis Rusby, S. cuzcoensis Hieron., S. hoppii B.L.Rob., S. melissiaefolia (Lam.) Sch.Bip., S. puberula Hook., S. weberbaueri B.L.Rob., Syncretocarpus sericeus (DC.) S. F. Blake, and *Wedelia hoffmanniana F.Bruns. The seven species marked with an asterisk are endemic to Arequipa. W. hoffmanniana has not been collected since 1923 (sheet Gunther 46, HBG).

We consider the following species as semi-endemic or endemic to the Xerophytic Punenian biogeographic province (Appendix A, Table A1; Supplementary Table S3): Aldama dilloniorum, Ambrosia dentata, A. pannosa, Aphyllocladus denticulatus (J.Rémy ex Gay) Cabrera, Aristeguietia cursonii, Diplostephium meyenii Wedd., Gochnatia arequipensis, Helogyne apaloidea Nutt., Lomanthus icaensis, L. mollendoensis, L. okopanus, Lophopappus cuneatus R.E.Fr., L. foliosus Rusby, Mutisia arequipensis, M. orbignyana Wedd., Onoseris minima, Ophryosporus bipinnatifidus, O. hoppii (B.L.Rob.) R.M.King and H.Rob., Pluchea absinthioides (Hook. and Arn.) H.Rob. and Cuatrec., Polyachyrus annuus I.M.Johnst., Senecio calcicola Meyen and Walp., S. crassilodix, S. neoviscosus, S. scorzonerifolius Meyen and Walp., S. yurensis, and Werneria esquilachensis Cuatrec.

The genus Chionopappus Benth., Heiseria E.E. Schill and Panero and Paquirea Panero and S.E. Freire are endemic to Peru. Paquirea genus is endemic to Arequipa only.

3.2. Distribution Patterns

In the PCA (Figure 3), specimens are arranged along the axes according to altitude (H) (Component 1) and Thermicity Index (It) (Component 2). Precipitation trends higher towards the negative values of Component 2, while the Thermicity Index (It) trends higher towards the positive values of the x-axis. Thus, species located further to the right of the ordinate axis are found in the thermotropical bioclimatic belt, while those located further to the left are found in the supra- and orotropical belts. This means that the distances to volcanoes, combined with very low rainfall and a higher thermicity index (It) and, in turn, with Arenosols (Are), Gypsisols (Gyp), Solonchaks (Sch) and Leptosols (Lep) denote the species that are concentrated on the thermotropical coastal belt. These species include Lomanthus icaensis (57), and L. mollendoensis (58,61,62), Ophryosporus bipinnatifidus (89), Polyachyrus annuus (102,103,104), and Senecio calcicola (109,110,111).

In the lower right quadrant of the PCA, there are species of the lower mesotropical belt, with slightly more precipitation, poorly consolidated soils (Regosols, Reg) and accumulations of calcium carbonate (Calcisols, Cal) from the Jurassic and Cretaceous of Arequipa. Among the species, we found Aldama dilloniorum (8), Ambrosia pannosa (1), Aphyllocladus denticulatus (18,19), Gochnatia arequipensis (48,50), Helogyne apaloidea (54), Senecio yurensis (120,128,130,133). Here we also found thermotropical species, generally from the coast, established with a certain probability on regosols and calcisols, such as Lomanthus okopanus (63), Ophryosporus hoppii (94), Polyachyrus annuus (101), and Senecio calcicola (107). In this quadrant we also found Pluchea absinthioides (97), typical of thermo-mesotropical watercourses, in arenosols and fluvisols, as is characteristic of riverside vegetation.

To the left of the ordinates, we found the greatest ecological diversity, with species ranging from mesotropical to cryorotropical bioclimates. Those closest to the negative part of the ordinate axis are of semi-arid ombrotype and are associated with andosols with poorly consolidated soils due to their proximity to volcanic cones. These include Aphyllocladus denticulatus (21), Diplostephium meyenii (33,34), Gochnatia arequipensis (44,46), Senecio neoviscosus (116), and S. yurensis (123). Among these species, we find both mesotropical and supratropical species, the latter corresponding to localities, that having a typical altitude of the mesotropical belt, are subject to thermal inversion, as is the case with 46 (2400 m, Gochnatia arequipensis) and 116 (2800 m, Senecio neoviscosus), located to the South-East of the city of Arequipa.

On the other hand, the species located on the negative side of the x-axis next to the ordinates combine the features of being located in andosols and cambisols, the proximity to volcanoes, and a lower rainfall. For example, Gochnatia arequipensis (47) was found on andosols and cambisols, 1 km from the volcanic cones of Chachani and under a dry mesotropical bioclimate; Senecio yurensis (129) was found under a semi-arid mesotropical bioclimate, but only 13 km from Pichu-Pichu and with similar edaphological characteristics. The leftmost species, Aristeguietia cursonii (27), Diplostephium meyenii (39) and Mutisia arequipensis (74,75) are in humid orotropical localities with deep soils; however, 27 and 74 are already above the x-axis, showing the importance of washed soils (Luvisols) due to increased rainfall.

In the upper left quadrant, the species Diplostephium meyenii (40) and Gochnatia arequipensis (53) from semi-arid mesotropical localities are prominent. In the first case, it is a mesotropical location at 3100 m a.s.l., an altitude that should correspond to the limit of the supratropical belt. In addition, 53 belongs to a point located on Phaeozems deep soils, and in more humid environments. The rest of the localities in this quadrant belong to the more humid areas in the interior of the territory studied, including species such as Aphyllocladus denticulatus (24,25), Lophopappus cuneatus (66), L. foliosus (68,69), Mutisia arequipensis (72,73,76), and M. orbignyana (81), which grow forming shrublands on Kastanozems or Phaeozems soils. Localities 24, 25 and 72 are from La Unión province; 24 has a cryorotropical thermotype only at 3659 m a.s.l., and 25 and 72 are orotropical at 3300 and 3600 m a.s.l. respectively, which seems to indicate a preferential exposure to southerly winds.

Supporting the PCA results, the correlation matrix (Figure 4) shows the correlation between the different PCA variables, between positive values if there is at least some correlation, or negative values if the correlation is negative. H (altitude) and DIST (distance to volcanoes) are negatively correlated, since at lower altitudes in the coastal desert, the distance to volcanoes is greater. However, P (precipitation) has a positive correlation with altitude because the highest precipitation values are at high altitudes in the Arequipa Region. Similarly, Are (Arenosols) have a negative correlation with altitude and precipitation, as most of the arenosols are on the coast. Kst (Kastanozems) and Pha (Phaeozems) have a positive correlation with precipitation as they are located in the most humid localities of the Andes. Andosols have a positive correlation with altitude as they are mainly found in the vicinity of volcanic cones, which are areas of higher bioclimatic levels, where the value of the thermicity index (It) is lower.

Most of the collections of endemic and semi-endemic species are in the thermotropical bioclimatic zone, that is, on the coast (Figure 5A). These species are: Ambrosia dentata, Heiseria irmscheriana, Helogyne hutchinsonii, Lomanthus icaensis, L. mollendoensis, Ophryosporus bipinnatifidus, Polyachyrus annuus, Senecio smithianus, and Wedelia hoffmanniana. However, the mesotropical belt also has a high number, which includes all the areas of the Arequipa Region between 2100 and 3100 m a.s.l. Here we find Ambrosia pannosa, Aldama dilloniorum, Aphyllocladus denticulatus, Diplostephium meyenii, Gochnatia arequipensis, Helogyne apaloidea, Lophopappus cuneatus, Ophryosporus hoppii, Pluchea absinthioides, Senecio calcicola, and S. yurensis. At the supratropical level, endemisms and semi-endemisms begin to decline, until only two collections extend to the cryorotropical belt. In the supratropical, we can find Aldama dilloniorum, Aristeguietia cursonii, Diplostephium meyenii, Gochnatia arequipensis, Lophopappus foliosus, Mutisia arequipensis, M. orbignyana, Paquirea lanceolata, Senecio neoviscosus, S. scorzonerifolius, and S. yurensis; in the orotropical Aphyllocladus denticulatus, Aristeguietia cursonii, Diplostephium meyenii, Lophopappus cuneatus, L. foliosus, Mutisia arequipensis, Mutisia orbignyana, Onoseris minima, Senecio crassilodix, S. yurensis and Werneria esquilachensis; and finally, in the cryorotropical, Aphyllocladus denticulatus and Diplostephium meyenii. The localities of the thermotropical belt are distributed among the ultrahyperarid to semiarid ombrotypes, an ombrotype that also reaches a higher proportion in the mesotropical belt. From dry to hyperhumid are supra, oro, and cryorotropical localities, many of them located in the interior valleys of the region, indicating that the Andean western slopes are much drier (Figure 5B).

The number of times that a species is found within a bioclimatic belt indicates whether or not it is a bioindicator (Figure 6). In contrast to species such as Ambrosia pannosa (mesotropical), Heiseria irmscheriana (thermotropical), Helogyne hutchisonii (thermotropical), Lomanthus mollendoensis (thermotropical), Paquirea lanceolata (supratropical) or Senecio smithianus (thermotropical), there are others with a wider dispersion, such as Senecio yurensis (from thermo- to orotropical), Diplostephium meyenii (from meso- to cryorotropical) or Gochnatia arequipensis (from thermo- to supratropical). Thermotropical bioindicators are Ambrosia dentata, Heiseria irmscheriana, Helogyne hutchisonii, Lomanthus icaensis, L. mollendoensis, L. okopanus, Ophryosporus bipinnatifidus, Polyachyrus annuus, Senecio smithianus, and Wedelia hoffmanniana; however, only one mesotropical bioindicator, Ambrosia pannosa, was found. The supratropical ones are Paquirea lanceolata, Senecio neoviscosus, and S. scorzonerifolius. On the orotropical belt only Onoseris minima, Senecio crassilodix and Werneria esquilachensis are bioindicators. There are no bioindicators on the cryorotropical belt among the endemisms and semi-endemisms of the Arequipa Region.

Figure 7A shows the soil groups by locality of collection. From this, we can deduce that there are two main distribution poles for Asteraceae endemisms and semi-endemisms, on saline or gypsiferous basic soils and sandy soils, and on andosols and cambisols. The first group of soils belongs mainly to the thermotropical soil type, while the second group of soils presents localities from thermotropical to cryorotropical, indicating a great extension of the andosols and their influence on the flora (see quadrants and eigenvectors in Figure 3).

If we analyze the number of Asteraceae endemisms and semi-endemisms found closest to the volcanoes of Arequipa (Figure 7B), we can observe that the greatest number of these are in the space between the Misti, Chachani and Pichu- Pichu volcanoes, in the vicinity of the city of Arequipa, perhaps originating from the influence of a large volcanic complex dated to at least the Eocene (56–37 m.y. ago). Materials from the other volcanoes continued to have an influence, but to a lesser extent. The species most closely linked to this volcanic environment spread over 50 localities are (Figure 8, Appendix A, Table A1; Supplementary Table S3): Aldama dilloniorum, Aphyllocladus denticulatus, Diplostephium meyenii, Gochnatia arequipensis, Lophopappus cuneatus, Mutisia orbignyana, Onoseris minima, Ophryosporus hoppii, Pluchea absinthioides, Senecio crassilodix, S. neoviscosus, S. yurensis, and Werneria esquilachensis.

For Aldama dilloniorum, Onoseris minima, Senecio neoviscosus, and Werneria esquilachensis this volcanic arc signifies a biogeographic barrier to the north (Figure 9).

4. Discussion

4.1. Diversity

Arequipa features 232 species of Asteraceae; 49 are endemic to the Peruvian territory, of which only 7 belong to the Arequipa Region. This means that the number of species in Peru decreases from north to south. La Libertad presents 456 species in its flora (135 national endemics, and an unknown number of regional endemics), Ancash 393 (164 national and 13 regional endemics), Lima 344 (120 national and 14 regional endemics), and Ica 72 (11 national and 1 regional endemics). The Ica Region contains very few species due to its small Andean area [49,50,51,52].

4.2. Distribution Patterns

Asteraceae species in Arequipa follow a distribution pattern linked to the climatic characteristics of the territory, soils, and volcanism. Thus, most of the species are found in the lower bioclimatic levels, between the thermotropical and mesotropical (Figure 3 and Figure 5), although some, such as Diplostephium meyenii or Senecio yurensis, extend as far as the orotropical and cryorotropical belts (Figure 8), probably due to their anemochore dispersal. Thus, we also find fewer endemics in the orotropical and cryorotropical levels, which means in the alpine zones, in accordance with the dispersal pattern of the family [53,54]. In other areas of the world, this fact is also recognized [35]; therefore, on the volcanic island of Tenerife (Canary Islands) there are also a large number of endemics living between the inframediterranean and mesomediterranean belts. However, in the territory studied, several Asteraceae species have a narrower distribution, taking into account that there is also a fairly clear separation between the species of the coastal desert and those of the Andean Mountain Range, and that in this desert, most of the endemisms are located in islands of vegetation in the high areas that receive rainfall (‘lomas’) [55].

This bioclimatic distribution is also paralleled by soil types; as saline and gypsiferous soils and arenosols are more prevalent in the hyperarid and ultrahyperarid thermotropical bioclimate of the coastal desert, other soil types are more linked to volcanic eruptions in the rest of Arequipa [33,56], with andosols noticeable when volcanic eruptions are more modern [46], especially at higher altitudes and lower It. In contrast, regosols and leptosols, which are stony and have a negative correlation with altitude and precipitation, arose from older volcanic eruptions (Figure 3).

Ancient volcanism was involved in the speciation of Asteraceae and their distribution [57,58]), as well as the aridity that began to originate in the Palaeocene (66–56 m.y. ago) in the western Andes [59], augmented by the strengthening of the Humboldt Current during the Eocene (56–37 m.y. ago) [60]. In this way, Villaseñor [57] concludes that volcanism created a large number of microhabitats suitable for the diversification of Asteraceae genera. However, modern eruptions have led to a decrease in biodiversity in the orotropical and cryorotropical zones, so that the number of endemic orotropical and cryorotropical bioindicators of Asteraceae in Arequipa is very low. This fact has been confirmed in several studies in other parts of the world, such as Kilimanjaro (Tanzania) [61], the Santorini archipelago (Greece) [32], Chile [62], and Argentinean Patagonia [34]. On the contrary, in non-volcanic territories, as is the case in the Sierra de Guadarrama in the Central System of the Iberian Peninsula, the oromediterranean and cryoromediterranean belts host at least 19 endemisms in a small territorial extension [63]. Related to this final observation, the Lima Region, with similar precipitation (humid and hyperhumid ombrotypes), and which has no modern volcanoes, has 21 oro-cryorotropical endemisms of Asteraceae [64], while the Arequipa Region has only 3.

Maps (Figure 8 and Figure 9) indicate a higher concentration of Asteraceae endemics and semi-endemics in the vicinity of the city of Arequipa. Brecheisen et al. [65] mapped the agricultural and urban expansion of the city in 1966, 1978, and 2019, which has begun to occupy part of the slopes of Chachani, Misti and Pichu-Pichu, endangering many of the populations studied through elimination and alteration. Therefore, we propose the creation of flora micro-reserves to help their conservation, inspired by models and legislation established in other countries [66].