Latrodectus occidentalis Valdez-Mondragon 2023, sp. nov.
Creators: name: Valdez-Mondragón, Alejandro
name: Cabrera-Espinosa, Luis A.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Theridiidae
Latrodectus
Latrodectus occidentalis

description: Latrodectus occidentalis Valdez-Mondragón sp. nov.
urn:lsid:zoobank.org:act: 3A193510-15D4-4E30-AAC3-DC224288C792
Figs 13‒81
Differential diagnosis
Females of Latrodectus occidentalis sp. nov. can be identified from those of other species of Latrodectus from Mexico by the combination of several features. Dorsal coloration: distinct red stripes and dots on dorsal surface of the abdomen: 1) one V-shaped stripe on anterior part (Fig. 25, red arrow), 2) long and sigmoid stripe dorsally along the abdomen (Fig. 25, blue arrow), and 4) two pairs of stripes towards lateral part of abdomen (Fig. 25, green arrows). Ventral coloration: abdomen with hourglass pattern always complete, wide, and never separated as in L. hesperus and L. mactans (Fig. 26). Body measurements (Figs 5–6): sternum coefficient (length/width) longer than other species analyzed herein, tibia-patella I longer than other species, tibia-patella coefficient longer than other analyzed species, femur I longer than other species, femur I and IV coefficient longer than other species, TT1 and TT4 coefficients slightly longer than other species. Angle between the spermathecae position in dorsal view longer than other species. Genital opening of epigynum wider than other species (Figs 29, 31–42 (ventral views)). Copulatory ducts forming four or five loops around spermathecae (Figs 30, 33–43 (ventral views), 72). Males: similar to females, but abdomen oval (Figs 17, 27–28). Coloration: ventrally, abdomen with hourglass pattern always complete, thinner than females (Fig. 28). Body measurements (Figs 7–8): sternum coefficient (length/width) longer than other species analyzed herein, tibia-patella 1 length and tibia-patella coefficient longer than other species, tibia-patella 1 coefficient longer than other species, tibia-patella 1 coefficient longer than other species, length and coefficient of femur I longer than other species, TT1 coefficient longer than other species, tibia-patella IV longer than other species, femur IV longer than on other species. Embolus with 3 coils, located distally on cymbium (Figs 44–48, red arrows), last coil extending medially, curving downwards along retrolateral part of palp, continuing ventrally, ending in a long thin tip (Figs 44–60). In L. mactans and L. hesperus (native species from North America), the embolus has 2 coils (Cabrera-Espinosa & Valdez-Mondragón 2021: figs 30–37).
Etymology
This species is a name in apposition and refers to the distribution of the species in the Spanish language: ‘ Occidente de México ’ (‘western Mexico’), ‘ occidentalis ’, that includes the states of Guerrero, Michoacán, Colima, and Jalisco (type locality).
Material examined
Holotype MEXICO – Jalisco • ♀; Municipality of Cocula, Camichines; 20.4991° N, 103.8020° W; 1268 m a.s.l; 1 Jun. 2020; C.I. Navarro-Rodríguez leg.; night collecting; CNAN-T01589.
Paratypes MEXICO – Jalisco • 1 ♁; same collection data as for holotype; CNAN-T01590 • 3 ♀♀, 2 ♁♁; same collection data as for holotype; CNAN-T01591, CNAN-T01593.
Other material
MEXICO − Colima • 1 ♀; Municipality of Coquimatlán, watering place Los Amiales; 19.1676° N, 103.834° W; 296 m a.s.l.; 16 Nov. 2020; A. Valdez, I. Navarro, A. Juárez, S. Nolasco leg.; LATLAX Ara-1074 • 5 ♀♀, 1 ♁, 2 immatures; Municipality of Minatitlán, 2.5 km NW of San Antonio crossroads; 19.438° N, 104.0019° W; 195 m a.s.l.; 16 Nov. 2020; A. Valdez, I. Navarro, A. Juarez, S. Nolasco leg.; diurnal collecting; LATLAX Ara-1073, Ara-1051, Ara-1061, Ara-1066. – Guerrero • 1 ♀; Municipality of Chilpancingo de los Bravo; 17.3119° N, 99.2979° W; 1205 m a.s.l.; 1 Jul. 2018; P. Solís, S. Rodríguez leg.; LATLAX Ara-0771 • 2 ♀♀; Municipality of Pilcaya, Botanical garden, Grutas de Cacahuamilma; 18.6703° N, 99.5134° W; 1145 m a.s.l.; 15 Oct. 2018; A. Valdez, P. Solís, I. Navarro, A. Juárez, L. Cabrera leg.; diurnal collecting; LATLAX Ara-0767, Ara-0772 • 1 ♀; Municipality of Quechultenango, Tourist Center Grutas de Juxtlahuaca; 17.4392° N, 99.1593° W; 923 m a.s.l.; 14 Oct. 2018; A. Valdez, P. Solís, I. Navarro, A. Juárez, L. Cabrera leg.; LATLAX Ara-1057 • 1 ♀; Municipality of Taxco de Alarcón, 10 km SW of Taxco, on the way to Cerro de Huixteco park; 18.5908° N, 99.6033° W; 2330 m a.s.l.; 21 Sep. 2018; D. Montiel leg.; LATLAX Ara-1065 • 1 ♀; Municipality of Taxco de Alarcón, Miguel Hidalgo Street, #23; 18.4197° N, 99.545° W; 930 m a.s.l.; 19 Sep. 2017; A. Valdez, I. Navarro, P. Solís, J. Valerdi leg.; LATLAX Ara-1075 • 2 ♀♀, 1 ♁, 1 immature; Municipality of Técpan de Galeana, path to microwave repeater El Tamarindo, 1.5 km SW of viewpoint Bahía de Papanoa; 17.2918° N, 101.045° W; 79 m a.s.l.; 22 Nov. 2020; A. Valdez, I. Navarro, A. Juárez, S. Nolasco leg.; diurnal collecting; LATLAX Ara-1056, Ara-1063, Ara-1064. – Jalisco • 1 ♀; same collection data as for holotype; 21 Sep. 2018; I. Navarro leg.; diurnal collecting; LATLAX Ara-0765 • 1 ♀; same collection data as for holotype; 5 Jan. 2019; I. Navarro leg.; LATLAX Ara-0776 • 1 ♀, 3 immatures; same collection data as for holotype; 21 Jun. 2019; A. Valdez, I. Navarro, L. Cabrera, J. Flores leg.; LATLAX Ara-1083, Ara-1084 • 6 ♀♀, 3 ♁♁, 6 immatures; municipality of Hostotipaquillo, 3 km SW of Hostotipaquillo; 21.0314° N, 104.0668° W; 1336 m a.s.l.; 8 Nov. 2020; A. Valdez, I. Navarro, A. Juárez, S. Nolasco leg.; LATLAX Ara-1043 to Ara-1050, Ara-1058, Ara-1059 • 3 ♀♀; Municipality of Jilotlán de los Dolores, 4 km S of Agua Bendita; 19.4634° N, 102.5112° W; 1406 m a.s.l.; 5 Nov. 2020; A. Valdez, I. Navarro, A. Juárez, S. Nolasco leg.; LATLAX Ara-1060, Ara-1071, Ara-1072 • 3 ♁♁; Municipality of Jilotlán de los Dolores, Agua Bendita; 19.4689° N, 102.546° W; 1163 m a.s.l.; 5 Nov. 2020; A. Valdez, I. Navarro, A. Juárez, S. Nolasco leg.; diurnal collecting; LATLAX Ara-1053 to Ara-1055 • 1 ♀; Municipality of Tomatlán, 9 km NO of Campo Acosta; 19.8327° N, 105.304° W; 109 m a.s.l.; 14 Nov. 2020; A. Valdez, I. Navarro, A. Juárez, S. Nolasco leg.; diurnal collecting; LATLAX Ara-1077 • 1 ♀, 1 immature; Municipality of Tonaya, 1 km W of Amacuautitlán; 19.8133° N, 104.0059° W; 905 m a.s.l.; 7 Nov. 2020; A. Valdez, I. Navarro, A. Juárez, S. Nolasco leg.; diurnal collecting; LATLAX Ara-1078 • 1 ♀; Municipality of Zapopan, Lince Cave, La Primavera common; 20.712° N, 103.57° W; 1605 m a.s.l.; 8 Nov. 2020; A. Valdez, I. Navarro, A. Juárez, S. Nolasco leg.; diurnal collecting; LATLAX Ara-1068. – Michoacán • 8 ♀♀, 10 immatures; Municipality of Coahuayana de Hidalgo, La Piedra hill; 18.6721° N, 103.6464° W; 65 m a.s.l.; 19 Nov. 2020; A. Valdez, I. Navarro, A. Juárez, S. Nolasco leg.; diurnal collecting; LATLAX Ara-1062, Ara-1067, Ara-1079, Ara-1080 • 1 immature; Municipality of Cotija de la Paz, Luis G. Urbina street; 19.8087° N, 102.6884° W; 1630 m.a.s.l; 6 Nov. 2020; A. Valdez, I. Navarro, A. Juárez, S. Nolasco leg.; diurnal collecting; LATLAX Ara-1052 • 1 ♀, 1 immature; Municipality of Tzitzio, 2 km O of Tzitzio; 19.572° N, 100.9235° W; 1466 m a.s.l.; 3 Nov. 2020; A. Valdez, I. Navarro, A. Juárez, S. Nolasco leg.; diurnal collecting; LATLAX Ara-1070.
Description
Female (holotype CNAN-T01589)
MEASUREMENTS. Total length 10.70. Carapace 4.30 long, 3.75 wide (ratio l/w: 1.14). Clypeus 0.75 long. Diameter AME 0.25, ALE 0.20, PME 0.22, PLE 0.23. Distance AME–ALE 0.14, ALE– PLE 0.22, PME–PLE 0.33, PME–PME 0.19. Leg I: total 28.80 (femur 8.10 +patella 2.30 +tibia 7.20 +metatarsus 8.70 +tarsus 2.50); leg II: 18.32 (5.50 +1.80 +4.00 + 5.30 +1.72); leg III: 13.23 (4.20 +1.48 +2.50 + 3.68 +1.37), leg IV: 24.18 (7.20 +2.08 +5.60 + 7.30 +2.00). Leg formula: 1-4-2-3.
COLORATION. Live adult specimen dark brown, with distinctive red stripes dorsally on abdomen (Figs 13–15, 25) and ventrally with a red hourglass pattern, complete, located between epigynum and spinnerets (red coloration pattern is lost under ethanol) (Fig. 26). Chelicerae dark brown, white apically. Sternum, labium, and endites dark brown. Legs dark brown, metatarsi and tarsi paler coloration than other segments (Figs 13–15, 25–26). Tarsi darker distally.
PROSOMA. Carapace with small translucid setae scattered across, dark setae on clypeus and posterior part of ocular region. Fovea transverse, M-shaped. In lateral view, clypeus oblique, protruding close to chelicerae. Eyes widely separated, different sizes (Fig. 70). In dorsal view of carapace, AER and PER recurved. AME slightly elevating, protruding from carapace. ALE and PLE protruding from carapace (Fig. 70). Sternum setose, subtriangular, shield shaped (Fig. 26). Labium setose, pale distally, trapezoidal, longer setae apically. Endites setose, pale distally, sub square, longer setae apically. Chelicerae with long setae distally, close to the fangs (Fig. 71). Palps with long setae, more setose in tarsus, with single toothed claw.
LEGS. Uniformly moderately setose throughout, tapering in metatarsi and tarsi (Figs 73–75). Femora I wider basally, femora I and IV slightly curved in lateral view. Tibiae I slightly curved distally. Three tarsal claws present, lateral claws with one row of teeth, which become larger distally. Tarsi IV with distinct comb macrosetae.
ABDOMEN. Globular, moderately setose, with all setae of uniform length (Figs 13, 15, 25–26).
EPIGYNUM. In ventral view oval, sclerotized and elevated, with oval and continuous opening, which is M-shaped in anterior part, opening 3.4× wider than long (Fig. 29). In posterior view, copulatory openings visible, separated by a median septum (Fig. 31). In dorsal view, four spermathecae, dumbbellshaped, two anterior slightly bigger than others; copulatory ducts thinned-walled, transparent, weakly sclerotized, coiled around duct between spermathecae (Fig. 30).
Male (paratype CNAN-T01590)
MEASUREMENTS. Total length 4.80. Carapace 2.00 long, 1.68 wide (ratio l/w: 1.19). Clypeus 0.40 long. Diameter AME 0.16, ALE 0.13, PME 0.14, PLE 0.13. Distance AME–ALE 0.06, ALE–PLE 0.06, PME–PLE 0.15, PME–PME 0.10. Leg I: total 17.70 (5.00 +1.06 + 4.50 +5.30 +1.84); leg II: 10.28 (3.00 +0.84 +2.34 + 2.88 +1.22); leg III: 7.25 (2.25 +0.68 +1.48 + 2.00 +0.84), leg IV: 13.53 (4.05 +0.90 +3.16 + 4.00 +1.42). Leg formula: 1-4-2-3.
C OLORATION. Live adult specimens black, paler than female, with distinctive red stripes dorsally on abdomen, white line around stripes (Figs 16–18, 27). Abdomen ventrally with a red hourglass pattern, complete, thinner than females (red coloration pattern is lost under ethanol) (Fig. 28). Chelicerae brown, paler than female, white apically. Palp femora and patellae, pale yellow; cymbium dark brown (Figs 44– 48). Sternum, labium, and endites paler brown than female, sternum with a pale brown line medially (Fig. 28). Leg femora dark brown, except femora III, which is pale orange (Figs 16, 18, 27–28). Tibiae pale orange, becoming dark brown towards joints. Metatarsi and tarsi pale orange (Figs 16–18, 27–28).
PROSOMA. Carapace with fewer small translucid setae scattered across than in female, less dark setae on clypeus and posterior part of ocular region than in female. Fovea transverse, M-shaped. In lateral view, clypeus oblique, protruding close to chelicerae (Fig. 76). Eyes widely separated, different sizes (Fig. 76). In dorsal view of carapace, AER and PER recurved (Fig. 76). AME slightly elevated, protruding from carapace. ALE and PLE protruding from carapace (Fig. 76). Chelicerae with long setae distally, close to fangs (Fig. 77). Sternum setose, subtriangular, shield shaped (Fig. 28). Labium setose, pale distally, trapezoidal, longer setae apically. Endites setose, pale distally, sub square, longer setae apically (Fig. 71).
LEGS. Uniformly moderately setose throughout, tapering in metatarsi and tarsi. Femora I slightly wider basally, femora I and IV less curved in lateral view than female. Tibiae I and IV slightly curved distally. Three tarsal claws present, lateral claws with one row of teeth, which become larger distally. Tarsi IV with distinct comb macrosetae.
ABDOMEN. Oval, longer than wide, and high, moderately setose, with setae all uniform length. ALS longer than PMS and PLS, oval colulus (Figs 17, 27–28, 81).
PALP. In retrolateral view, cymbial apophysis (ca) oval, setose: with tegular apophysis (ta), hook-shaped, transparent, weakly sclerotized (Figs 44–48, 78–80). In ventral-basal view, median apophysis bent, almost 90° degrees, ending in blunt point, with a notch in the middle (Fig. 46).
Variation
Females have black carapace and abdomen coloration, black or dark brown legs, never light shades (Figs 25–26). Globular abdomen always black with distinctive red lines in dorsal region (Figs 61–69, red coloration is lost under ethanol), lines may be outlined by a thin white line in juveniles. The frontal region of the dorsal sigmoidal line may or may not be separated at an isolated point between the rest of the line and the V-shape. The two pairs of lines laterally may be attenuated or reduced, but always present (Figs 13–15, 25, 61–69). Males always present a black body coloration (Fig. 17), legs black or dark brown with light brown on the mid tibia, metatarsus, and tarsus (Figs 17–18). Abdomen oval with distinctive red lines on the dorsal region, which may be outlined by a thin white line (Figs 17–18, 27). As in females, the frontal region of the transverse dorsal line may or may not be separated at an isolated point between the rest of the line and the V-shape (Fig. 27). Males can vary greatly in body size (Table 4), however sexual dimorphism is always marked, with females being more than twice the size of males, but males with proportionately longer legs (Tables 4–5). The genital opening of females varies in shape, but is always wider than long (Figs 29, 32–42 (ventral views)), the spermathecae are arranged in a V-shape surrounded by the copulatory ducts which may have four or five turns around them (Figs 33–43 (dorsal views)). The angle of the spermathecae may vary, but they are never parallel as in L. geometricus (Table 5). Palps of males show little variation, sclerites with little variation, embolus always with three complete turns (Fig. 46); however, there is variation in the apical part (Figs 49–60).
Males (N = 12): Tibia-Patella I: 5.31–6.8 (x = 5.77); T coefficient: 1.08–1.25 (x = 1.19). Females (N = 30): Tibia-Patella I: 6.4–9.1 (x = 7.96); T coefficient: 0.98–1.22 (x = 1.11). See Table 4 and 5 for intra and interspecific morphological variation.
Natural history
The specimens were collected in their cobwebs in natural and anthropized localities (Figs 19–24). The species is distributed mainly in tropical deciduous forests in the western states of Mexico: Jalisco, Guerrero, Michoacán, Colima, Guanajuato, Morelos, and Oaxaca (Fig. 21). The specimens from the type locality were collected inside the same house, under chairs, on window frames, under stowed dishes, and furniture (Figs 23–24, red arrows). Specimens collected in nature were found under and between big boulders on the ground (Figs 19, 22, red arrow), under mounds of rocks, inside cavities on walls along road-cuts, at the bases of alive cacti such as “nopales” (Opuntia spp.) and columnar cacti, and even under rotten cacti (Figs 19–21). Some females were collected with egg sacs, which are usually big, oval and yellow in coloration (Fig. 15), differing from other Mexican species (e.g. Latrodectus sp. 1 and sp. 2) that have smaller egg sacs whitish or pale-yellow in coloration.
Distribution
MEXICO: Jalisco, Colima, Michoacán, Guerrero, Oaxaca, Morelos, Guanajuato (Fig. 10).
description: Published as part of Valdez-Mondragón, Alejandro & Cabrera-Espinosa, Luis A., 2023, Phylogenetic analyses and description of a new species of black widow spider of the genus Latrodectus Walckenaer (Araneae, Theridiidae) from Mexico; one or more species?, pp. 1-56 in European Journal of Taxonomy 897 on pages 27-43, DOI: 10.5852/ejt.2023.897.2293, http://zenodo.org/record/8405868