Stenochrus alcalai, 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 : 203-206

Stenochrus alcalai , sp. nov.

Figs. 43–56 , 71, Table 4.

Type material. MEXICO : Oaxaca : male holotype ( CNAN-T1160 ), [23 August 2015, D. Barrales, J. Cruz, O. Francke, R. Monjaraz, J. Sánchez], from La Laguna, (17.72716ºN, 97.10172ºW, 2402m), San Pedro Jocotipac . Paratypes: 1 female ( CNAN-T1161 ), same data as holotype . 2 males 1 female ( CNAN-T1162 ), [22 August 2016, D. Barrales, J. Cruz, O. Francke, R. Monjaraz, J. Sánchez], from El Tanque (17.74294ºN, 97.10562ºW, 2402m), San Pedro Jocotipac.

Distribution. This species is known only from the type locality and a second locality fairly close by and in the same forest ( Fig 71).

Habitat. Specimens were collected in a very well conserved and hyper-humid oak forest, the trees festooned with mosses and lichens, above 2,400 m elevation; individuals were found under rocks and rotten logs.

Etymology. The specific name is a noun in apposition dedicated to Diego Barrales Alcalá for his help during field trips and for his contributions to Mexican arachnology.

Diagnosis. Males can be distinguished by having an ovate shaped flagellum with one pair of deep dorsosubmedian pits ( Figs. 45–47 ); with homeomorphic pedipalps. Females can be distinguished by the spermathecae ( Fig. 56 ) with median lobes inverse “J” shaped, with duct openings along the entire lobe; lateral lobes straight, slender and shorter than median lobes; the bases of the lobes very close to each other and at the same level. Stenochrus alcalai resembles Stenochrus pecki ( Rowland, 1973) in the ovate shape of the flagellum in males; however, the flagellum in S. alcalai presents a pair of deep dorsosubmedian pits, whereas in S. pecki it presents a single shallow posteromedian depression. In addition, male pedipalps in S. pecki are robust and with spiniform setae on patella and tibia; whereas on S. alcalai the pedipalps are normal and bear acuminate setae. Females of S. alcalai resemble S. chimalapas in the general shape of the spermathecae; however, females of S. chimalapas present wide lateral tips on the chitinized arch, and few duct openings; whereas females of S. alcalai present duct openings along the entire lobes, and with slender lateral tips; also, the bases of the lobes are fused in S. alcalai , whereas in S. chimalapas are separated and independent; finally, females of S. alcalai present a large, conical gonopod, whereas females of S. chimalapas have a short and wide gonopod.

Description. Male (holotype): Brownish ( Fig. 43 ). Prosoma: propeltidium with two setae on anterior process (one behind the other) and three pairs of dorsal setae; ocular spots distinct, asymmetrical. Metapeltidium 0.42 long, 0.72 wide. Anterior sternum with nine setae, plus two sternophysial setae; posterior sternum with six setae.

Chelicerae ( Figs. 53–55 ): Movable finger: serrula with 12 teeth, guard tooth present. Fixed finger with five smaller teeth between two primary teeth. Setation: setal group formula: 3-6-4-2-6-5-1-5. G1 with three spatulate setae, with few apical 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, thick basally, elongated at the tip; G5A with six similar sized setae, feathered apically and longer than fixed finger; G5B with five feathered setae, increasing in size distally; G6 with one smooth setae, about 1/2 of movable finger length; G7 with five smooth, slender setae, decreasing in length distally.

Pedipalps ( Figs. 51 ): 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, medial mesal spur. Femur 2 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 3:3:5 Ter acuminate, Tmr and Tir feathered. Tarsal spurs asymmetrical.

Legs: Leg I, basitarsal-telotarsal proportions: 31: 4: 5: 4: 6: 5: 12. Femur IV 3.4 times longer than high.

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 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 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 microsetae.

Flagellum ( Figs. 45–47 ): dorsoventrally flattened, ovate in shape; 1.7 times longer than wide; with a pair of deep dorsosubmedian pits. Setation: Dm1 situated over the bulb base; Dm4 situated medially; Dl2 anterior to Vl1; Dl3 at same level as Vl2; pair Vm2 present; seta Vm1 at same level as 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 two patches of microsetae between Vl1 and Vl2 (msp).

Female (paratype) ( Fig. 44 ): Pedipalps slightly shorter than on male ( Fig. 52 ), 1.6 times longer than propeltidium length. Setation as on male except for anterior sternum with 10 setae. Flagellum with three flagellomeres ( Figs. 48–50 ). Setation: seta Dl2 reduced and anterior to Vl1; Dl3 posterior to Vl2; Vm2 present and not reduced; seta Vm1 at same level as Vm2; microsetae Dl1 and Dl4 present. Spermathecae ( Fig. 56 ) with two pairs of lobes, with bases fused and at the same level; median pair inverse “J” shaped outwards, longer than lateral pair, with duct openings along the entire length, ending in a blunt tip; lateral pair slender and shorter, about 1/2 length of median lobes, without duct openings, ending in a blunt tip. Chitinized arch U- shaped; with a wide lateral tip and without anterior branch. Gonopod 3.6 times wider than long, sub rectangular-shaped. Chelicera: serrula with 13 teeth. Setal group formula 3-6-4-2-7-6-1-5. Fixed finger with four teeth between two primary teeth.

Remarks. The altitudinal distribution of this species (2402m) is rare in schizomids, with S. alcalai representing the highest record thus far of the genus Stenochrus . Without evidence of dimorphic males (n=3).

Male CNAN- Female CNAN- Male CNAN- Male CNAN- Female CNAN- T1160 T1161 T1162 T1162 T1162 ......continued on the next page Male CNAN- Female CNAN- Male CNAN- Male CNAN- Female CNAN- T1160 T1161 T1162 T1162 T1162

Figures

FIGURES 43, 44. Stenochrus alcalai sp. nov. Male holotype.Habitus: 43. Dorsal view. Female paratype.Habitus: 44. Dorsal view.

FIGURES 45–52. Stenochrus alcalai sp. nov. Male holotype. Flagellum (45–47): 45, dorsal view. 46, ventral view.47, lateral view. Female. Flagellum (48–50): 48, dorsal view. 49, ventral view. 50, lateral view. Pedipalps ectal view (51, 52): 51, Homeomorphic male. 52, female.Scale bars = 0.2 mm.

FIGURES 53–56. Stenochrus alcalai sp. nov. Male. Chelicera (53–55): 53, movable finger. 54, mesal view. 55, fixed finger. Female.Spermathecae:56, dorsal view. Scale bar (Fig. 56) = 0.05 mm.