Stenochrus caballero, Monjaraz-Ruedas & Francke, 2018

Monjaraz-Ruedas, Rodrigo & Francke, Oscar F., 2018, Five new species of Stenochrus (Schizomida: Hubbardiidae) from Oaxaca, Mexico, Zootaxa 4374 (2), pp. 189-214 : 199-203

Stenochrus caballero , sp. nov.

Figs. 29–42 , 71, Table 3.

Type material. MEXICO : Oaxaca: male holotype ( CNAN-T1157 ), [10 April 2014, G. Contreras, J. Cruz, S. Davlantes, O. Francke, J. Mendoza], from Cerro Caballero, (18.14230ºN, 96.71597ºW, 938m), San José Tenango . Paratypes: 1 male and 1 female ( CNAN-T1158 ), [28 August 2008, J. Cruz ] same locality data as holotype . 1 male and 1 female ( CNAN-T1159 ), [11 April 2014, G. Contreras, J. Cruz, S. Davlantes, O. Francke, J. Mendoza] from 0.6 km N of Pozo de Águilas , (18.19772ºN, 96.67682ºW, 327m), San José Tenango.

Distribution. This species is known from the foothills of the Sierra Mazateca in the northern region of Oaxaca ( Fig 71).

Habitat. Specimens were collected in tropical dry forest under big rocks in both conserved and disturbed habitats.

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

Diagnosis. Relatively larger and darker than most congeners. Males can be distinguished by having an oval shaped flagellum with one pair of dorsosubmedian depressions ( Figs. 31–33 ); pedipalps not elongated (=homeomorphic), trochanter without apical process ( Fig. 37 ). Females can be distinguished by the spermathecae ( Fig. 42 ) having median and lateral lobes of the same length and width, with their insertions at the same level. Chelicerae with a remarkable accessory tooth on movable finger ( Fig. 39 ). Stenochrus caballero resembles Stenochrus pallidus ( Rowland, 1975) in the oval shape of the male flagellum; however, males of S. pallidus present a pair of deep dorsosubmedian pits, whereas males of S. caballero present a pair of shallow dorsosubmedian depressions. Females of S. caballero differ from S. pallidus in having the median and lateral lobes of the spermathecae of the same length, whereas female spermathecae in S. pallidus with lateral lobes shorter than the median lobes.

Description. Male (holotype): Dark brownish ( Fig. 29 ). Prosoma: propeltidium with two setae on anterior process (one behind the other) and three pairs of dorsal setae; ocular spots distinct, irregular. Metapeltidium 0.37 long, 0.66 wide. Anterior sternum with 11 setae, plus two sternophysial setae; posterior sternum with six setae.

Chelicerae ( Figs. 39–41 ): Movable finger: Serrula with 21 teeth, guard tooth present, with a prominent accessory tooth at the middle of the movable finger. Fixed finger with four smaller teeth between two primary teeth. Setation: Setal group formula: 3-6-4-2-7-6-1-7. G1 with three spatulate setae, covered with spicules starting from the middle of the shaft; 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, distally elongated; G5A with seven similar sized setae, feathered apically and longer than fixed finger; G5B with six setae, two short and smooth proximally and four long and feathered distally; G6 with one smooth setae about 1/2 of movable finger length; G7 with seven smooth setae, slightly decreasing in size distally.

Pedipalps ( Fig. 37 ): homeomorphic; 1.7 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 small, distal mesal spur. Femur, 1.9 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 four feathered Pm setae; without distinctive ornamentations. Setae formula on tibia 4:3:5, Ter acuminate, Tmr and Tir feathered. Tarsal spurs asymmetrical.

Male CNAN- Male CNAN- Female CNAN- Male CNAN- Female CNAN- T1157 T1158 T1158 T1159 T1159 Legs: Leg I, basitarsal-telotarsal proportions: 29: 4: 5: 5: 6: 5: 14. Femur IV 2.41 times longer than high. Opisthosoma: Tergite I with two pairs of microsetae anteriorly plus pair Dm; tergite II with three pairs of microsetae anteriorly plus pair Dm; tergites III–VIII with setae pair Dm each; 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 scattered setae.

Flagellum ( Figs. 31–33 ): dorsoventrally flattened, ovoid in shape; 1.9 times longer than wide; with a pair of dorsosubmedian depressions. Setation: Dm1 situated over the bulb base; Dm4 situated distally; Dl2 at same level as Vl1; Dl3 posterior to Vl2; pair Vm2 present; seta Vm1 posterior to Vm2; Vm 5 posterior to Vl1. With one pair of anterodorsal microsetae between Dm1 and Dl2, one pair of anterolateral microsetae on flagellar pedicel and with two patches of microsetae between Vl1 and Vl2 (msp).

Female (paratype) ( Fig. 30 ): Pedipalps similar to male ( Fig. 38 ), 1.6 times longer than propeltidium length. Setation as on male. Flagellum with three flagellomeres ( Figs. 34–36 ). Setation: seta Dl2 reduced and anterior to 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. 42 ) with two pairs of lobes; both median and lateral lobes of the same length and width, median pair straight, ending in a blunt tip; lateral pair slightly curved inwards, ending in a blunt tip; median and lateral lobes bases at the same level. Chitinized arch U-shaped; with wide lateral tip, and a straight and incomplete anterior branch. Gonopod 2.4 times wider than long, lobe-shaped. Chelicera: movable finger with a prominent accessory tooth; serrula with 22 teeth. Setal group formula 3-6-4-2-7-4-1-7. Fixed finger with four teeth between two primary teeth.

Remarks. The large size (4.4–4.6 mm) of the specimens in this species and S. alcalai sp. nov. is an uncommon characteristic in members of the genus Stenochrus which has in general species with small body size (2.5 to 3.8). There is no evidence of dimorphism on male pedipalps among the three known specimens, but we can’t rule out their existence. There are two important characteristics present in this species which render difficult the correct placement of this species in Stenochrus: The lateral lobes of female spermathecae of the same length as the median lobes, and the presence of an accessory tooth on movable finger of the chelicerae. However, there are other characters, as are the shape and relief of the male flagellum, and the general shape of the pedipalps, that permit us to group this species with members of Stenochrus . We tentatively place this species in Stenochrus due to the lack of evidence on the morphological limits of Stenochrus , and because there is no other described genus with the combination of characters mentioned above; its correct taxonomic placement should be resolved in the phylogenetic analyses in progress.

Figures

FIGURES 29, 30. Stenochrus caballero sp. nov. Male holotype. Habitus: 29. Dorsal view. Female paratype. Habitus: 30. Dorsal view.

FIGURES 31–38. Stenochrus caballero sp. nov. Male holotype. Flagellum (31–33): 31, dorsal view. 32, ventral view. 33, lateral view. Female. Flagellum (34–36): 34, dorsal view. 35, ventral view. 36, lateral view. Pedipalps ectal view (37, 38): 37, Homeomorphic male. 38, female.Scale bars = 0.2 mm.

FIGURES39–42. Stenochruscaballero sp.nov. Male.Chelicera(39–41): 39, movable finger.40, mesal view.41, fixed finger. Female.Spermathecae:42, dorsal view. Scale bar (Fig. 42) = 0.05 mm.