Latrodectus occidentalis Valdez-Mondragón, 2023

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?, European Journal of Taxonomy 897, pp. 1-56 : 27-43

publication ID

https://doi.org/ 10.5852/ejt.2023.897.2293

publication LSID

lsid:zoobank.org:pub:A340BD2E-094A-4C84-88B3-5B4ED220F476

DOI

https://doi.org/10.5281/zenodo.8415063

persistent identifier

https://treatment.plazi.org/id/FF24F904-5A76-6523-068B-FECC28B8FBE9

treatment provided by

Plazi

scientific name

Latrodectus occidentalis Valdez-Mondragón
status

sp. nov.

Latrodectus occidentalis Valdez-Mondragón sp. nov.

urn:lsid:zoobank.org:act:3A193510-15D4-4E30-AAC3-DC224288C792

Figs 13‒81 View Figs 13–18 View Figs 19–24 View Figs 25–28 View Figs 29–31 View Figs 32–43 View Figs 44–48 View Figs 49–60 View Figs 61–69 View Figs 70–75 View Figs 76–81

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 View Figs 25–28 , red arrow), 2) long and sigmoid stripe dorsally along the abdomen ( Fig. 25 View Figs 25–28 , blue arrow), and 4) two pairs of stripes towards lateral part of abdomen ( Fig. 25 View Figs 25–28 , green arrows). Ventral coloration: abdomen with hourglass pattern always complete, wide, and never separated as in L. hesperus and L. mactans ( Fig. 26 View Figs 25–28 ). Body measurements ( Figs 5–6 View Fig View Fig ): 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 View Figs 29–31 View Figs 32–43 (ventral views)). Copulatory ducts forming four or five loops around spermathecae ( Figs 30 View Figs 29–31 , 33–43 View Figs 32–43 (ventral views), 72). Males: similar to females, but abdomen oval ( Figs 17 View Figs 13–18 , 27–28 View Figs 25–28 ). Coloration: ventrally, abdomen with hourglass pattern always complete, thinner than females ( Fig. 28 View Figs 25–28 ). Body measurements ( Figs 7–8 View Fig View Fig ): 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 View 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 View Figs 44–48 View Figs 49–60 ). 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 . GoogleMaps

Paratypes MEXICO – Jalisco • 1 ♁; same collection data as for holotype; CNAN-T01590 GoogleMaps 3 ♀♀, 2 ♁♁; same collection data as for holotype; CNAN-T01591 , CNAN-T01593 GoogleMaps .

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 GoogleMaps 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 GoogleMaps . – 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 GoogleMaps 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 GoogleMaps 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 GoogleMaps 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 GoogleMaps 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 GoogleMaps 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 GoogleMaps . – Jalisco • 1 ♀; same collection data as for holotype; 21 Sep. 2018; I. Navarro leg.; diurnal collecting; LATLAX Ara-0765 GoogleMaps 1 ♀; same collection data as for holotype; 5 Jan. 2019; I. Navarro leg.; LATLAX Ara-0776 GoogleMaps 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 GoogleMaps 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 GoogleMaps 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 GoogleMaps 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 GoogleMaps 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 GoogleMaps 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 GoogleMaps 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 GoogleMaps . – 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 GoogleMaps 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 GoogleMaps 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 GoogleMaps .

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 View Figs 13–18 , 25 View Figs 25–28 ) and ventrally with a red hourglass pattern, complete, located between epigynum and spinnerets (red coloration pattern is lost under ethanol) ( Fig. 26 View Figs 25–28 ). 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 View Figs 13–18 , 25–26 View Figs 25–28 ). 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 View Figs 70–75 ). In dorsal view of carapace, AER and PER recurved. AME slightly elevating, protruding from carapace. ALE and PLE protruding from carapace ( Fig. 70 View Figs 70–75 ). Sternum setose, subtriangular, shield shaped ( Fig. 26 View Figs 25–28 ). 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 View Figs 70–75 ). 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 View Figs 70–75 ). 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 View Figs 13–18 , 25–26 View Figs 25–28 ).

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 View Figs 29–31 ). In posterior view, copulatory openings visible, separated by a median septum ( Fig. 31 View Figs 29–31 ). 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 View Figs 29–31 ).

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 View Figs 13–18 , 27 View Figs 25–28 ). Abdomen ventrally with a red hourglass pattern, complete, thinner than females (red coloration pattern is lost under ethanol) ( Fig. 28 View Figs 25–28 ). Chelicerae brown, paler than female, white apically. Palp femora and patellae, pale yellow; cymbium dark brown ( Figs 44– 48 View Figs 44–48 ). Sternum, labium, and endites paler brown than female, sternum with a pale brown line medially ( Fig. 28 View Figs 25–28 ). Leg femora dark brown, except femora III, which is pale orange ( Figs 16, 18 View Figs 13–18 , 27–28 View Figs 25–28 ). Tibiae pale orange, becoming dark brown towards joints. Metatarsi and tarsi pale orange ( Figs 16–18 View Figs 13–18 , 27–28 View Figs 25–28 ).

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 View Figs 76–81 ). Eyes widely separated, different sizes ( Fig. 76 View Figs 76–81 ). In dorsal view of carapace, AER and PER recurved ( Fig. 76 View Figs 76–81 ). AME slightly elevated, protruding from carapace. ALE and PLE protruding from carapace ( Fig. 76 View Figs 76–81 ). Chelicerae with long setae distally, close to fangs ( Fig. 77 View Figs 76–81 ). Sternum setose, subtriangular, shield shaped ( Fig. 28 View Figs 25–28 ). Labium setose, pale distally, trapezoidal, longer setae apically. Endites setose, pale distally, sub square, longer setae apically ( Fig. 71 View Figs 70–75 ).

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 View Figs 13–18 , 27–28 View Figs 25–28 , 81 View Figs 76–81 ).

PALP. In retrolateral view, cymbial apophysis (ca) oval, setose: with tegular apophysis (ta), hook-shaped, transparent, weakly sclerotized ( Figs 44–48 View Figs 44–48 , 78–80 View Figs 76–81 ). In ventral-basal view, median apophysis bent, almost 90° degrees, ending in blunt point, with a notch in the middle ( Fig. 46 View Figs 44–48 ).

Variation

Females have black carapace and abdomen coloration, black or dark brown legs, never light shades ( Figs 25–26 View Figs 25–28 ). Globular abdomen always black with distinctive red lines in dorsal region ( Figs 61–69 View 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 View Figs 13–18 , 25 View Figs 25–28 , 61–69 View Figs 61–69 ). Males always present a black body coloration ( Fig. 17 View Figs 13–18 ), legs black or dark brown with light brown on the mid tibia, metatarsus, and tarsus ( Figs 17–18 View Figs 13–18 ). Abdomen oval with distinctive red lines on the dorsal region, which may be outlined by a thin white line ( Figs 17–18 View Figs 13–18 , 27 View Figs 25–28 ). 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 View Figs 25–28 ). Males can vary greatly in body size ( Table 4 View 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 View Table 4 View Table 5 ). The genital opening of females varies in shape, but is always wider than long ( Figs 29 View Figs 29–31 , 32–42 View Figs 32–43 (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 View Figs 32–43 (dorsal views)). The angle of the spermathecae may vary, but they are never parallel as in L. geometricus ( Table 5 View Table 5 ). Palps of males show little variation, sclerites with little variation, embolus always with three complete turns ( Fig. 46 View Figs 44–48 ); however, there is variation in the apical part ( Figs 49–60 View 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 View Table 4 and 5 View Table 5 for intra and interspecific morphological variation.

Natural history

The specimens were collected in their cobwebs in natural and anthropized localities ( Figs 19–24 View 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 View Figs 19–24 ). 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 View Figs 19–24 , red arrows). Specimens collected in nature were found under and between big boulders on the ground ( Figs 19, 22 View Figs 19–24 , 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 View Figs 19–24 ). Some females were collected with egg sacs, which are usually big, oval and yellow in coloration ( Fig. 15 View Figs 13–18 ), 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 View Figs 9–10. 9 ).

Kingdom

Animalia

Phylum

Arthropoda

Class

Arachnida

Order

Araneae

Family

Theridiidae

Genus

Latrodectus

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