Holotype. México • ♂; Jalisco, Municipio la Huerta: Estación de Biología, IBUNAM; Chamela-Cuixmala, 19°29.88'N, 105°02.61'W, 97 m, 31.VIII.2007, O. Francke, A. Valdez, H. Montaño, A. Ballesteros, and C. Santibáñez leg, collected on the ground; CNAN-T0689. Paratypes. Same locality • 1 ♂ (CNAN-SC01506), 2.IV.1989, E. Ramírez leg; • 2 ♀, collected inside bromeliads (CNAN-SC01506), collected inside bromeliads; E. Ramírez leg; • 2 ♂, 2 ♀, collected inside bromeliads (AMNH); 2-IV-1989, E. Ramírez leg; • 2 ♂, 2 ♀, collected inside bromeliads (INDRE); 2.IV.1989, E. Ramírez leg; • 1 ♀, collected inside bromeliads (INDRE) 2-IV-1989, E. Ramírez leg, • 1 ♀ (INDRE); • 1 ♂, 1 ♀, collected on the ground (FBUMSNH); • 1 ♂, camino a Chachalacas, 19°29.620'N. 105°02.749'W (FBUMSNH).

This species is endemic to the Pacific lowlands of Jalisco, most likely mirroring the distribution of C. elegans.

This is the only arboreal member of the striped species group of the genus Centruroides (González-Santillán 2004). All other Mexican species of arboreal species are found in the thorelli species group, recently revised by Goodman et al. (2021). The authors indicated that the distribution of Centruroides chanae Goodman, Prendini, Francke & Esposito, 2021, the only species of the thorelli group distributed in the Pacific coast of Mexico, reaches the limits of the littorals of Colima and Michoacán. We infer that C. chamela substitutes C. chanae ecologically in the littorals of Jalisco. Besides, there are no records of any species resembling species of the thorelli group, and our recent fieldwork in the EBC produced only the two species cited here. We tested the potency of the venom of this species and are preparing a report on it; our preliminary results indicate that the potency is comparable to that of C. elegans.

Holotype. Mexico • deposited at the Naturhistoriska Museet, Goteborg, Sweden (not examined).

Mexico • Jalisco, Municipio la Huerta: Estación de Biología Chamela, 11.5.1989, 19°29.91'N, 105°2.67'W, 80 m, G. Ortega leg (CNAN-SC259), 1 ♂, 2 ♀; • 23.X.2001, 80 m, E. González-Santillán leg (CNAN-SC279), 1 ♂, 2 ♀; • 15.IX.1977, 80 m, N. Pérez (CNAN-SC260), 22 ♂, 4 ♀; • 3.VI.1975, G. Casas leg (CNAN-SC245), 4 juvs; • 16.XII.1998, 80 m, D. Estrada leg, 1 ♀ (CNAN-SC246) 1 ♂, 1 ♀; • 26.III.2000, 280 m, E. González-Santillán leg (CNAN-SC243); • 26.xi.2004, 80 m, A. Valdez leg (CNAN-SC269), 1 ♂; • 24.xi.2004, 13 m, A. Valdez leg (CNAN-SC271), 1 ♀; • 27.XII.1984, L.J. Vitt leg (CNAN-SC272) 22 juvs, 1 ♀; • Camino el Tejón, 18.VIII.2005, 19°29.84'N, 105°02.49'W, 86 m, J.L. Costelo, L.A. Gutierrez leg (CNAN-SC274), 2 ♀; • Playa Negritos, 15.V.2008, 19°31.76'N, 105°04.82'W, 31 m, S. Soriano, M. Vega, M. Hernández, C. Guzmán, R. Paredes leg (CNAN-SC247), 1 ♂, 1 ♀; • Playa Teopa, 19°24.06'N, 105°12.20'W, 7 m, E. González-Santillán leg (CNAN-SC244), 1 ♀.

Jalisco lowlands from Puerto Vallarta to Marabasco River, which is the natural border between Jalisco and Colima (González-Santillán et al. 2024).

This species is responsible for most of the acute envenomations reported in the coast of Jalisco (González-Santillán and Possani 2018). Our observations at the EBC indicated that is highly synanthropic, it is commonly found inside station buildings and dorms.

Holotype. Mexico: • Jalisco, Municipio la Huerta: 1 ♂, allotype ♀, and seven ♂ topoparatypes, collected at Estación de Biología, Chamela, UNAM, 10–11.VII.1985, S. C. Williams leg, ultraviolet detection. Holotype depository: California Academy of Sciences, type no. 15744 (Williams 1986).

Mexico: • Jalisco, Municipio de La Huerta: Estación de Biología Chamela, UNAM, 23.iv.1980, S.H. Bullok leg (CNAN-SC3850), 1 ♀; • 31.V.1990, N. Martínez leg (CNAN-SC3848), 1 ♀; • Vereda Verdin, 23.X.2001, E. González and J.L. Castelo leg (CNAN-SC3849), 1 ♂; • Rincón de Ixtlán, 19°329'N, 105°049'W, 24.X.2001, E. González leg (CNAN-SC3851), 1 ♀.

It has been reported only within the limits of the EBC.

Konetontli chamelaensis is an inhabitant of the leaf litter in the EBC and appears to be active on the surface during the rainy season (González-Santillán and Prendini 2015).

Holotype . Mexico: • 1 ♀, deposited at Naturhistoriska Riksmuseet Stockholm, Sweden (not examined).

Mexico: • Jalisco: Municipio la Huerta: Estación de Biología Chamela, 4.IV.1977, M. Varela-Juliá leg (CNAN-SC2244), 1 ♀; • 5.IX.1990, S.H. Bullock leg (CNAN-SC2920), 1 ♂; • 97 m, 19°29.875'N, 105°02.608'W, 31.VIII.2007, O. Francke, A. Valdez, H. Montaño, A. Ballesteros, C. Santibáñez leg (CNAN-SC2245), 3 ♂, 1 ♀; (CNAN-SC2617) ♀.

For a comprehensive compilation of records for this species refer to Chávez-Samayoa et al. (2024).

The ecology of this species is poorly known, despite being the largest species and being distributed in a wide range of altitudes, from sea level to almost 2000 m a.s.l. (Chávez-Samayoa et al. 2024), and its biological interactions and microhabitat are unknown. Like K. chamelaensis, its superficial activity occurs during the rainy season, but even then, it is not abundant.

Holotype. Mexico: • Jalisco, Municipio La Huerta: ♂ (CNAN-T01869) and Allotype 1 ♀ (CNAN-T01870) Estación Biológica Chamela, IBUNAM, Sendero Calandria, 19°30.30'N, 105°2.30'W, 95 m, 4.X.2010, G. Montiel, R. Paredes, D. Barrales, and G. Contreras leg. Paratypes. Mexico: • Jalisco, Municipio La Huerta: Sendero Tejón, 19°30'N, 105°2.55'W, 63 m, 2.x.2010, G. Montiel, R. Paredes, D. Barrales, and G. Contreras leg, 2.X.2010 (CNAN-T01871), 8 ♂, 2 subadult 1 ♀.

Mexico: • Jalisco, Municipio La Huerta, Estación de Biología Chamela, IBUNAM, Chamela-Cuixmala, 19°29.87'N, 105°2.61'W, 97 m, O. Francke, A. Valdéz, H. Montaño, A. Ballesteros, C. Santibáñez leg, 30.VIII.2007 (CNAN-SC02910), 3 ♂, 19 ♀, 9 juv., 39 2^nd instar juvs; • G. Casas leg, 3.VI.1975 (CNAN-SC2964), 1 ♂; (CNAN-SC2965), 2 ♂; E. Ramírez leg (CNAN-SC2963), 1 ♀; • D. Verduzco leg, 9.IX.2001 (CNAN-SC2967), 1 juv.; • D. Verduzco leg, 25.IX.2001 (CNAN-SC2971), 1 ♂; • M.A. Morales and A.M Corona leg, 12.XI.1998 (CNAN-SC02969), 1 ♀; • R. Ayala leg, 13.X.1993 (CNAN-SC2970), 1 ♂; • M. Córdova leg, X.2005 (CNAN-SC2972), 1 ♂; • A. B. López leg, 16.X.1994 (CNAN-SC2968), 4 ♂; • M. Guzmán, M. Hernández, R. Paredes, S. Solano, M. Vega leg, 13.V.2008 (CNAN-SC2953), 1 ♀, 1 juv.; • M. Ayala leg, 3.IX.1989 (CNAN-SC2952), 1 ♀; • A. Rodríguez leg, 20.VI.1994 (CNAN-SC2962), 1 ♂; • J. Guzmán leg, 28.VII.1989 (CNAN-SC2959), 1 ♂; • A. M. Corona leg, 29.III.1999 (CNAN-SC2958), 1 ♂; • A. López leg, 18.VI.1994 (CNAN-SC2961), 1 ♂, R. Ayala leg, 22.VII.1998 (CNAN-SC2960), 1 ♀; • N. Martí leg, 23.VIII.1990 (CNAN-SC2954), 1 ♀; • A. Rodríguez leg, 19.IX.1992 (CNAN-SC2956), 1 ♂; • E. Ramírez leg, 21.IX.1990 (CNAN-SC2955), 1 ♀; • E. González leg, 24.X.2001 (CNAN-SC2957), 1 ♀; • S.C. Williams leg, 12.VII.1985 (CNAN-SC02948), 4 ♀; • Sendero Tejón, E. González leg, 22.X.2001 (CNAN-SC2950), 6 ♀; • Pueblo Careyes, F. A. Noguera, A. Rodríguez leg, 20.VII.1999 (CNAN-SC2966), 1 ♀. • Bahía Chamela, L. Olguín, S. Reynaud, E. González leg, 21.X.2001 (CNAN-SC2949), 3 ♂, 3 ♀, 2 juvs; • Punta Pérula, orillas de estero, 19°35.46'N, 105°7.61'W, 20 m, 10.x.2017, C. Balderas, G. Balderas, T. Olamendi, H. Valencia, I. Gómez, E. González-Santillán leg (CNAN-SC4070), 14 ♂, 8 ♀.

Mesomexovis caxcan sp. nov. is closely related to M. occidentalis (Hoffmann, 1931), Mesomexovis subcristatus (Pocock, 1898), and Mesomexovis atenango (Francke & González-Santillan, 2006) by having mesosomal tergites and ventral submedian carinae on metasomal segments III–IV granular. Mesomexovis caxcan sp. nov. may be distinguished from M. occidentalis by having all carinae of pedipalp chelae outlined with dark pigmentation, costate, and weakly crenulate, instead of immaculate; except for dorsal retrolateral and ventral retrolateral carinae that are costate, all other carina are obsolete and smooth. Mesomexovis caxcan sp. nov. differs from M. subcristatus by having ventral lateral carinae of metasomal segments I–IV granular and ventral submedian carinae of segments II–IV costate to granular, instead of costate to weakly crenulate and obsolete to weakly costate, respectively. Mesomexovis caxcan sp. nov. differs from M. atenango by having dusky markings on carapace and mesosomal tergites, instead of diffused and weakly visible infuscation. Finally, Mesomexovis caxcan sp. nov. differs from M. atenango and M. subcristatus by having three or four setae on the ventrolateral carinae of metasomal segment V instead of seven or eight, or ten or eleven, respectively.

The following description is based on the male type and male and female paratypes.

Color and infuscation in alcohol : base color yellowish to dark orange; carapace, tergites, and prolateral surface of legs femur, patella, tibia, and tarsi infuscate with dusky markings (Fig. 5). Pedipalp femur and patella with dorsal, prolateral, and retrolateral carinae outlined with diffuse infuscation. Pedipalp chelae with all carinae moderately infuscate. Pectines and genital operculum whitish. Dorsal median and dorsal submedian carinae in tergites I–VI outlined with intense infuscation. Sternite VII with base of setae on ventral submedian and ventral lateral carinae intensely infuscate, weakly converging in ventral submedian carina. Metasomal segments I–IV, ventral lateral and ventral submedian carinae, and metasomal segment V ventral lateral and ventral median carinae outlined with intense infuscation. Ventral surface of telson infuscate with two lateral and a median longitudinal broad band of dusky markings.

Chelicerae : manus dorsal surface smooth with one median macrosetae on subdistal margin, distal margin with costate carinae. Base of fixed finger with low crenulation. Serrula with 14 spines in distal half.

Carapace : length 1.14/1.12× greater than posterior width (Table 1). Anterior margin emarginate, with a vestigial to obsolete median notch, with five pairs of major and a median macrosetae. Entire surface shagreened, with minute and moderately large granules over most of the surface (Fig. 6). Anteromedian, and posteromedial sulci moderate, posterolateral sulci deep, posterior transverse sulcus obsolete. Median ocular tubercle moderately raised, with superciliary carinae smooth, higher than median eyes, positioned on distal half of carapace. Median ocelli approximately double the size of lateral frontal pairs. Lateral ocelli of type 3A (Loria and Prendini 2014). Three lateral eyes, mediolateral major ocellus, posterolateral major ocellus similar size and posterolateral minor ocellus, reduced approximately in half, and with an eyespot ventrally (Fig. 7).

Coxosternal region : sternum subequilateral pentagonal; width 1.63/1.74× greater than length (Table 1); with four pairs of setae, one distal, two median pairs, and one pair on the lobes, median notch deep. Anterior margin of coxae II with two oblique slit-like structures (Fig. 8A), adjacent to a strong and crenulate protuberance (Fig. 8B). Coxal endite II proximal median margin with a deep depression. Coxa IV 2.03/2.20× longer than coxa II (Table 1).

Pedipalps : femur and intercarinal surfaces matte, dorsal and ventral surfaces with scattered minute to moderate median granules (Fig. 9). Dorsal prolateral, dorsal retrolateral, and ventral prolateral carinae granular; retrolateral dorso-submedian carina obsolete, smooth with four major macrosetae, distal one reduced; prolateral ventro-submedian carina vestigial with an enlarged proximal tubercle positioned medially with a row of four or five moderate to large rounded granules/ subdistal, median and distal granules with a macroseta at the base, slanting gently towards median portion of dorsal prolateral carinae; prolateral ventral carina vestigial, expressed by a proximal tubercle with a macroseta at base and two enlarged rounded granules with a macroseta at base; intercarinal surface between prolateral ventral and ventral prolateral with three macrosetae; ventral median and retrolateral ventral carinae vestigial expressed by scattered serrated granules; ventral retro-submedian carinae expressed by irregular granules, present on proximal half. Patella 1.27/1.21× wider than femur (Table 1). Intercarinal surfaces matte (Fig. 10). Dorsal prolateral and ventral prolateral carinae complete, granular; dorsal retrolateral and ventral retro-submedian carinae complete, crenulated to smooth; ventral median carina vestigial expressed as a short proximal row of granules; retrolateral dorso-submedian and retrolateral median carinae obsolete, expressed by bands of infuscation and a weak median costa; prolateral process well-developed; prolateral median carina expressed as a row of five to six coarse subserrated granules, median one with a macroseta, the row slanting gently at the level of trichobothrium d₂ towards dorsal prolateral carinae, followed by a gap of smooth surface and ending on one distal major macrosetae, positioned on the distal fifth of dorsal prolateral carinae; prolateral ventral carina obsolete expressed by a row of three major macrosetae and two intersperse minor macrosetae, proximal major macrosetae on the top of a low granule. Chela 1.52/1.51× longer than patella, 1.72/1.76× longer than femur (Table 1). Manus relatively slender (Fig. 11), 1.42/1.35× wider than patella, 1.80/1.64× wider than femur. Intercarinal surface smooth with a weak reticular infuscation. Dorsal median, dorsal retrolateral, dorsal prolateral, and prolateral median carinae complete costate finely granular (Fig. 11E); ventral retrolateral carina incomplete moderately costate, ending by the level of trichobothrium Est; ventral median carina weak, crenulate; ventral prolateral carina moderately costate. Trichobothrium Db positioned on dorsal retrolateral carina, subbasal on chelae; Dt positioned close to mid manus. Fixed and movable fingers dentate margins emarginate, fixed finger proximal notch strong and median lobe moderate, movable finger proximal notch weak and median lobe moderate, large gap created when fingers closed, fingers fit unevenly (♂), or proximal notch and median lobe of fixed finger and movable fingers gap created when fingers closed moderated (♀). Fixed finger median denticle row comprising six denticle subrows flanked by six prolateral and six retrolateral subserrate, subpaired denticles, proximal retrolateral denticle positioned by proximal third of finger; movable finger median row comprising seven denticle subrows, flanked by seven prolateral and seven retrolateral denticles, proximal retrolateral denticle positioned by proximal third of finger. Trichobothria ib and it positioned submedian on fixed finger, ib positioned adjacent to sixth prolateral denticle and it between fifth and sixth prolateral denticle (♂). Trichobothrial pattern Type C, orthobothriotaxic.

Legs : Basitarsi I–III prolateral ventral, retrolateral ventral and retrolateral dorsal carinae with complete rows of spinules, basitarsi IV prolateral ventral and retrolateral ventral carinae devoid of spinules, retrolateral dorsal carina with scattered spinules. Macrosetal counts on carinae of legs I–IV, respectively: Prolateral ventral, 3:4:5:5, proximal three in leg III and IV stouts (Fig. 12); retrolateral ventral, 4:7:8:8; retrolateral median, absent; retrolateral dorsal, 2-3:2-3:2-3:2-3; dorsal, 2-3:2-3:2-3:2-3; retrolateral dorsal and dorsal series arranged in two independent rows. Telotarsi I–IV with two to three pairs of ventrodistal spinules (Fig. 12); macrosetal counts on legs I–IV proventral/retroventral: 0/0:1/1:1/1:2/2 unpaired, retroventral distal, proventral proximal.

Genital operculum : Wider than long, with three pairs of macrosetae. Sclerites free on longitudinal edges moving independently but unable to open more than 45°. Genital papillae protruding posteriorly (♂) or sclerites fuse longitudinal (♀).

Hemispermatophore : Lamina 1.3× longer than stem (Fig. 13). Laminar hook positioned on the apex of distal carina (Figs 14A–1, B-1, 15A-1, C-1). Hook bicuspid, short and low, separated from the anterior margin of the laminar base, forming a shallow notch (Figs 14A–1, 15A–1, C-1). Contralateral through strongly sclerotized (Fig. 15A–2, C-2). Lateral through margin short, wide, tapering, and curving proximally, moderately removed from contra-lateral through (Fig. 15C–5). Architecture of the capsule conforms to the three-fold bauplan (Monod et al. 2017). Hemi-mating plug developed from the basal carina (14A-5, 6), distal barb margin with 14 elongated spinules (Fig. 14B–10). Basal carina posterior surface or basal plate (González-Santillán and Prendini 2013) rounded with two extensions forming a double wing-like structure and with a second spinoid projection raising towards the opposite side of the wing-like structure (Fig. 14B–7). Distal barb with one strongly sclerotized spine localized on the lateral surface pointing backwards (Fig. 14B–8). Base of the distal barb with a spatulated strongly sclerotized projection on contralateral surface (Fig. 14B–11). Distal barb 1.5× longer than the basal plate. Subex with two structures (Figs 14A–6, B-12, 15A-6, B6), the pouch-like invagination, rounded with two sharp projections situated on the posterior aspect (Figs 14B–12, 15B–6) and connects to the anterior aspect with the sperm duct, a spatulated projection adjacent to the capsular foramen (Figs 14B–13, 15A–7, B-4). Terminal membrane, thick, tightly connects the tectum (Fig. 15A–3), basal carina, and subex (Fig. 14B–14). Truncal flexure prominent (Fig. 14A–4). Measurements: lamina, 3.22; trunk, 2.46; dorsal trough/laminar hooks, 0.81; ventral trough/laminar hook, 0.34; distal barb, 1.26; basal plate, 1.96; pedicel 1.17.

Pectines : longer than distal edge of coxa IV (♂) or at the level of distal edge of coxa IV (♀). Basal piece with median notch deep (Fig. 16). Marginal lamella consists of three sclerites, medial lamella proximally fuses distally progressively forming conspicuous 14 or 15 (♂), or 12 or 13 (♀) beads. Fulcra with 19–21 (♂), 17–20 (♀) beads. Pectinal tooth count 20–22 (♂) or 18–21 (♀).

Tergites : pretergites and postergites matte proximally, postergites distally shagreened. Tergites I–VI dorsal median and ventral submedian carinae vestigial, expressed by few moderate or minute distal granules (♂), or granular (♀) (Fig. 5). Tergite VII with intercarinal surfaces shagreened; dorsal median carina costate-granular expressed on proximal half of the postergite; dorsal submedian vestigial expressed as a short, oblique, proximal row of granules; dorsal lateral and lateral supramedian granular, merging proximally creating a semi ring of strong serrated granulation.

Sternites : I–VI smooth, matte in (♂), in ♀ finely punctuated, and lustrous (Fig. 17). Sternite V distal margin with a triangular, whitish glandular area (♂) or (♀) homogeneously colored. Sternite VII matte laterally and punctuated smooth ventrally; ventral lateral carinae partial, granular, expressed on median third; ventral submedian obsolete expressed by three pairs of macrosetae. Spiracle elongated, slit-like, ~ 3× longer than wide.

Metasoma : 1.82/1.49× longer than mesosoma. Segments I–V, respectively 0.84, 1.03/0.95, 1.13/1.03, 1.50/1.34, 2.30/2.06× longer than wider; V, 1.30/1.16× wider than telson vesicle. Segments I–V, dorsal and lateral intercarinal surface with fields of scatter granules medially (Fig. 17), ventral surface of metasomal segment I and III smooth with few small granules, IV and V smooth with few fields of granules medially more so on V; dorsal lateral and lateral median carinae on I–IV, moderately serrated; lateral median carina on IV distal terminus expanded or flared laterally forming a triangular projection (Fig. 17A, B); dorsal lateral carina on V proximally third strongly serrated, becoming weaker and crenulated with irregular clusters of crenulations medially, moniliform distally; lateral inframedian carina on I complete serrated; on II incomplete serrated, becoming weaker proximally, present in distal third; on III incomplete serrated, present in distal fourth; on IV and V absent (Fig. 17B); ventral lateral carina on I–V strongly serrate (Fig. 17C); ventral submedian carina on I costate and smooth, on II costate and smooth on with distal end crenulate, on III weakly costate and smooth on two proximal thirds distal third crenulate, on IV proximal half smooth, distal half serrated, on V absent; ventral median carina on V strongly serrate (Fig. 18C). Macrosetal counts on carinae of segments I–V, respectively: Dorsal lateral, 1:3:3:3:5; lateral median, 2:3:3:4:5; lateral inframedian, 2:1:1:0:0; ventral lateral, 3:4:4:4-6:10, setae on V positioned laterally to the carinae instead on the carina; ventral submedian, 3:3:3:3-5:6; ventral sublateral, 2. Accessories macrosetae absent.

Telson : vesicle 1.70/1.46× longer than wide; 1.83/2.01× longer than aculeus; elongated, dorsal surface smooth to moderately granular (♂) or comparatively more globose and more granular (♀) (Fig. 18A, B). Subaculear tubercle moderately broad and low. Microserration on laterobasal aculeus 3–5 (♂), or 2–3 (♀) (Fet et al. 2006).

Mesomexovis caxcan sp. nov. is distributed along Jalisco’s littoral and Colima. Inhabits tropical dry forest, including tropical deciduous forest and tropical broadleaf forest. This species was identified as a lapidicolous (González-Santillán 2004), although we found that the prolateral ventral carina on legs III and IV are armed with three, proximal, stout macrosetae (Fig. 12), which are characteristic of fossorial scorpions. At the EBC, the species is commonly found under rocks and rotten logs, although during recent fieldwork we observed females using abandoned burrows in a sit-and-wait foraging strategy. Males exhibit increased surface activity during the rainy season and thus are easily spotted during the night using ultraviolet detection.

López-Granados (2019) conducted a phylogenetic analysis on specimens from Chamela, Jalisco, and Coquimatlán, Colima that formed a monophyletic group with two synapomorphies, body color brownish and ventral surface of metasomal segment V with setae basis pigmented and areolas unpigmented. Granados-López observed that the number of setae on the carinae was lower in this species than in others. For instance, M. caxcan sp. nov. had only five setae on the fifth segment carina, whereas other species had as many as 12 (López-Granados 2019). The author diagnosed the clade with the following features: the carina on the pedipalp manus and the first three ventral segments of the metasoma tended to be costate to crenulate. Our observations confirm these features in all examined Chamela specimens. López-Granados (2019) identified seven clades that potentially represent undescribed species, among which M. caxcan sp. nov. is the closest to the outgroup. Remarkably, all clades maintain a constant pattern with their distribution. Mesomexovis caxcan sp. nov. represents the first divergent clade and occupies the northern limit of distribution range of the species complex. The remaining clades follow a laddered arrangement from the more ancient to the more recently divergent clade following a distribution north-south on the Pacific lowland biogeographic province identified by Morrone et al. (2017). González-Santillán et al. (2024) concluded that genetically, the specimens from Jalisco and Colima are not conspecific with the specimens identified as M. occidentalis (González-Santillán and Prendini 2015), confirming the earlier observation of Sissom (1989). These observations justify the description of M. caxcan sp. nov. from a morphological, biogeographical, and genetic perspective.

The species name caxcan is derived from the name of one of the original nomadic groups of Chichimeca peoples that occupied the arid land of northern Mexico. The name is a noun in apposition.