Stenochrus chimalapas Monjaraz-Ruedas & Francke 2018, sp. nov.

Stenochrus chimalapas, sp. nov.

Figs. 1–14, 71 Table 1.

Type material. MEXICO: Oaxaca: male holotype (CNAN-T1152), [25 October 2016, E. Briones, A. Juárez, A. Valdez, J. Valerdi], from Cueva de Escolapa, (16.85057ºN, 94.7481ºW, 219m), Municipio Santa María Chimalapas. Paratypes: 1 male and 2 females (CNAN-T1153) same data as holotype. 2 males (CNAN-T1154), [28 March 2010, J. Cruz, O. Francke, C. Santibañez, A. Valdez] same locality as holotype.

Distribution. This species is known only from the type locality (Fig 71).

Habitat. Collected inside the cave, which is about 50 to 60m long; specimens were collected in the deepest area in complete darkness, and were moving on the ground and the walls, between bat guano and moist organic material that had washed into the cave.

Etymology. The specific name is a noun in apposition taken from the type locality.

Diagnosis. Males can be distinguished by having an elliptical shaped flagellum with one pair of dorsosubmedian pits (Figs. 3–5); pedipalps with femur, patella and tibia elongated (Fig. 9). Females can be distinguished by the spermathecae (Fig. 14) with median lobes inverse “J” shaped, lateral lobes straight. Stenochrus chimalapas sp. nov. resembles S. moisii, both species with small body size and dark body coloration, and in both species the male flagellum with a pair of dorsosubmedian pits, however male flagellum in S. moisii has a pair of small submedian protuberances. Additionally, males of S. chimalapas sp. nov. have elongated pedipalps with respect to females, i. e., there is evident sexual dimorphism, whereas males of S. moisii with pedipalps very similar to the females. Females of S. chimalapas sp. nov. resemble S. valdezi in the shape of the spermathecae, having inverse “J” shaped median lobes; however, S. valdezi has lateral lobes with pointed tips, whereas the lateral pair is blunt in S. chimalapas sp. nov., and significantly, the chitinized arch of the spermathecae of S. chimalapas sp. nov. lacks the anterior branches.

Description. Male (holotype): Greenish (Fig. 1). Prosoma: propeltidium with two setae on anterior process (one behind the other) and two pairs of dorsal setae; ocular spots distinct, asymmetrical. Metapeltidium 0.30 long, 0.45 wide. Anterior sternum with eleven setae, including two sternophysial setae; posterior sternum with six setae.

Chelicerae (Figs. 11–13): Movable finger: Serrula with 18 teeth, guard tooth present. Fixed finger with six smaller teeth between two primary teeth. Setation: Setal group formula: 3-6-4-2-7-5-1-5. G1 with three spatulate setae, apically covered with few small spinose spicules; G2 composed of six feathered setae, subequal in length, and shorter than movable finger length; G3 with four setae, subequal in length, feathered apically and smooth basally; G4 consisting of two small setae, smooth, basally thick, elongated at the tip; G5A with seven similar sized setae, feathered apically and longer than fixed finger; G5B with five feathered setae, three apical ones longer than basal two; G6 with one smooth seta, about 1/2 of movable finger length; G7 with five slender, feathered setae, subequal in size.

Pedipalp (Figs. 9, 10): elongated; 1.95 times longer than propeltidium length. Trochanter without apical process, mesal surface with three setae near ventral margin, plus two setae near dorsal margin; with a long distal mesal spur. Femur, 2.4 times longer than high; ventral margin on ectal surface with setae Fe1, Fe5, Fev1 and Fev2 acuminate; mesal surface with a row of three ventral setae (Fmv 1–3) plus two dorsal setae (Fmd2, Fmd3). Patella with three acuminate Pe setae and three feathered Pm setae; without distinctive armature. Setae formula on tibia 3:3:4 (external row (Ter): medial row (Tmr): internal row (Tir)), all setae on tibia acuminate. Tarsal spurs asymmetrical.

Legs: Leg I, basitarsal-telotarsal proportions: 15: 4: 3: 3: 4: 4: 10. Femur IV 2.32 times longer than high.

Male CNAN- Male CNAN- Female CNAN- Female CNAN- Male CNAN- Male CNAN- T1152 T1153 T1153 T1153 T1154 T1154 Opisthosoma: Tergite I with two pairs of microsetae anteriorly plus pair Dm; tergite II with three pairs of microsetae anteriorly, plus Dm pair; tergites III–VII with one pair of Dm setae each; tergite VIII with Dm and Dl2; tergite IX with pairs Dl1, Dl2 and without Dm. Segments X, XI telescoped, with setal pairs Dl2, Vm2, Vl1 and Vl2, plus single Vm1 seta; segment XII with Dm, Dl1, Dl2, Vm1, Vm2, Vl1 and Vl2 setae, without posterodorsal process. Sternites with two irregular rows of setae each; genital plate with many scattered microsetae.

Flagellum (Figs. 3–5): dorsoventrally flattened, elliptical in shape; 1.6 times longer than wide; with a pair of dorsosubmedian shallow pits. Setation: Dm1 situated over the bulb base; Dm4 situated distally; Dl2 anterior to Vl1; Dl3 at same level as Vl2; pair Vm2 present; seta Vm1 at same level as Vm2; Vm 5 distal to Vl1. One pair of anterodorsal microsetae between Dm1 and Dl2, one pair of anterolateral microsetae on flagellar pedicel, and two patches of microsetae between Vl1 and Vl2 (msp).

Female (paratype) (Fig. 2): Pedipalps shorter and without enlargement as on male, 1.8 times longer than propeltidium length. Setation as on male. Flagellum with three flagellomeres (Figs. 6–8). Setation: seta Dl2 reduced and at same level as Vl1; Dl3 at same level as Vl2; Vm2 present and not reduced; seta Vm1 at same level as Vm2; microsetae Dl1 and Dl4 present. Spermathecae (Fig. 14) with two pairs of lobes; median pair inverse “J” shaped outwards, longer than lateral pair, with few disperse duct openings ending in a blunt margin; lateral pair shorter, about 1/2 of the median lobes, with apical duct openings; median lobes bases starting anterior to those of lateral lobes. Chitinized arch U-shaped; with wide lateral tip and without anterior branch. Gonopod 2.1 times wider than long, sub rectangular-shaped, sides parallel. Chelicera: serrula with 19 teeth. Setal group formula 3-6-4-2-6-6- 1-5. Fixed finger with six teeth between two primary teeth.

Remarks. There are dimorphic males in this species, having particularly an enlargement in the femur, patella and tibia of the pedipalps; the dimorphic male (heteromorphic) with the longest pedipalps having a ratio of 3.2 times longer than propeltidium length; whereas the homeomorphic male, with the shorter pedipalps having a ratio of only 1.7 times longer than propeltidium length: There are two intermediate (mesomorphic) males (including the male holotype) that have a ratio of pedipalp length of 2.3 and 2.7 times longer than propeltidium length. Noteworthy is the dark greenish coloration of the species, which is an uncommon feature in cave dwelling species of Stenochrus.