Stenochrus gruta, 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 : 195-199

Stenochrus gruta , sp. nov.

Figs. 15–28 , 71, Table 2.

Type material. MEXICO: Oaxaca: male holotype ( CNAN-T1155 ), [1 July 2013, G. Contreras, J. Cruz, J. Mendoza, C. Santibáñez, A. Valdez], from Gruta de San Sebastián, (16.03049ºN, 96.9692ºW, 1715m), San Sebastián de las Grutas, Municipio Sola de Vega . Paratypes: 2 males and 2 females ( CNAN-T1156 ), same data as holotype .

Additional material examined. MEXICO: Oaxaca: 6 females (CNAN-Sz0193), [20 June 2006, O. Francke, H. Montaño, C. Santibáñez, A. Valdez, G. Villegas], from Gruta de San Sebastián , (16.03049ºN, 96.9692ºW, 1715m), San Sebastián de las Grutas, Municipio Sola de Vega .

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

Habitat. The cave is a horizontal tunnel about 800m long, open at both ends. Specimens were collected inside the cave in moist, dark areas associated with bat guano, about 300 m into the long passage. The cave is promoted and used as an ecotouristic attraction; however, it is conserved in very good conditions, so we suspect that there are few visitors because it is located some distance away from the main roads.

Etymology. The specific name is a noun in apposition referring to the name of the type locality.

Diagnosis. Males can be distinguished by having a rhomboidal shaped flagellum with one pair of dorsomedian pits ( Figs. 17–19 ); pedipalps noticeably elongated ( Fig. 23 ). Females can be distinguished by the spermathecae ( Fig. 28 ) having median lobes curved along their length, about 1/3 longer than lateral lobes; lateral lobes straight, their base distal to that of median lobes, with an extremely wide gonopod. Stenochrus gruta sp. nov. resembles S. moisii in the rhomboidal shape of the male flagellum; however, males of S. gruta sp. nov. have pedipalps elongated, and larger body size; whereas males of S. moisii have homeomorphic pedipalps and small body size. Stenochrus gruta sp. nov, also resembles S. mexicanus in both having elongated pedipalps; however, males of S. mexicanus have a tibial apophysis on mesal surface, absent in the new species. Female spermathecae of S. gruta sp.

nov. resemble those of S. portoricensis , both having curved median lobes with apical openings, but S. gruta sp. nov. differs from S. portoricensis in the length and width of the lateral lobes.

Description. Male (holotype): Brownish ( Fig. 15 ). Prosoma: propeltidium with two setae on anterior process (one behind the other) and two pairs of dorsal setae; ocular spots distinct, oval shaped. Metapeltidium 0.44 long, 0.72 wide. Anterior sternum with nine setae, plus two sternophysial setae; posterior sternum with six setae.

Chelicerae ( Figs. 25–27 ): Movable finger: serrula with 20 teeth, guard tooth present. Fixed finger with six smaller teeth between two primary teeth. Setation: Setal group formula: 3-6-4-2-8-3-1-6. G1 with three spatulate setae, covered with small spinose spicules starting from base of 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, thick basally, elongated at the tip; G5A with eight similar sized setae, feathered apically and longer than fixed finger; G5B with three setae, two apical ones longer, smooth basally and feathered distally, and basal seta short and smooth; G6 with one smooth seta about 1/2 of movable finger length; G7 with seven apically feathered setae, subequal in size.

Pedipalps ( Figs. 23, 24 ): elongated, 3.4 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 tiny, distal mesal spur. Femur, 5.6 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 five Pe acuminate setae and three Pm feathered setae; without distinctive armature. Setae formula on tibia 3:3:4, Ter acuminate, Tmr and Tir feathered. Tarsal spurs asymmetrical.

Legs: Leg I, basitarsal-telotarsal proportions: 27: 4: 5: 4: 4: 5: 13. Femur IV 2.6 times longer than high.

Male CNAN- Male CNAN- Male CNAN- Female CNAN- Female CNAN- T1155 T1156 T1156 T1156 T1156 Opisthosoma: Tergite I with two pairs of microsetae anteriorly plus pair Dm; tergite II with three pair microsetae anteriorly plus pair Dm; tergites III–VII with setae pair Dm 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. 17–19 ): dorsoventrally flattened, rhomboidal in shape; 1.7 times longer than wide; with a pair of dorsomedian 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; Vm5 posterior to Vl1. With one pair of anterodorsal microsetae between Dm1 and Dl2, one pair of anterolateral microsetae on flagellar pedicel, and two patches of microsetae (msp) between Vl1 and Vl2.

Female (paratype) ( Fig. 16 ): Pedipalps shorter and without enlargement as on male, 1.9 times longer than propeltidium length. Setation as on male. Flagellum with three flagellomeres ( Figs. 20–22 ). Setation: seta Dl2 reduced and at same level as Vl1; Dl3 at same level as Vl2; Vm2 present and not reduced; seta Vm1 anterior to Vm2; microsetae Dl1 and Dl4 present. Spermathecae ( Fig. 28 ) with two pairs of lobes; median pair curved outwards along their length, longer than lateral pair, with apical duct openings ending in a blunt tip; lateral pair straight, slightly shorter and narrower than median pair, without duct openings; median lobes bases starting basal to lateral lobes bases. Chitinized arch U-shaped; lateral tip not sclerotized and without anterior branch. Gonopod 4.2 times wider than long, conical-shaped. Chelicera: serrula with 21 teeth. Setal group formula 3-6-4-2-7-5-1-6. Fixed finger with six teeth between two primary teeth.

Remarks. Males of S. gruta sp. nov. have a very remarkable dimorphism in the length of the pedipalps; in this species we observed two types of males (heteromorphic and homeomorphic), where one male (heteromorphic) with the longest pedipalps presents a ratio of 3.4 times longer than propeltidium length, and the homeomorphic male with shortest pedipalps presenting a ratio of only 2.1 times longer than propeltidium length.

Figures

FIGURES 15, 16. Stenochrus gruta sp. nov. Male holotype. Habitus: 15. Dorsal view. Female paratype. Habitus: 15. Dorsal view.

FIGURES 17–24. Stenochrus gruta sp. nov. Male holotype. Flagellum (17–19): 17, dorsal view. 18, ventral view. 19, lateral view. Female. Flagellum (20–22): 20, dorsal view. 21, ventral view. 22, lateral view. Pedipalps ectal view (23, 24): 23, Heteromorphic male.24, Homeomorphic male.Scale bars = 0.2 mm.

FIGURES 25–28. Stenochrus gruta sp. nov. Male. Chelicera (25–27): 25, movable finger. 26, mesal view. 27, fixed finger. Female.Spermathecae:28, dorsal view. Scale bar (Fig. 28) = 0.05 mm.