Troglostenochrus, Monjaraz-Ruedas & Prendini & Francke, 2019

Monjaraz-Ruedas, Rodrigo, Prendini, Lorenzo & Francke, Oscar F., 2019, Systematics Of The Short-Tailed Whipscorpion Genus Stenochrus Chamberlin, 1922 (Schizomida: Hubbardiidae), With Descriptions Of Six New Genera And Five New Species, Bulletin of the American Museum of Natural History 2019 (435), pp. 1-93 : 74-75

Troglostenochrus , gen. nov.

Figures 4 , 6, 7I, 9F, 13I, 23G–I, 24G–I, 25C, D; tables 1, 4

Stenochrus (part): Monjaraz-Ruedas, 2012: 63 , 64; Monjaraz-Ruedas and Francke, 2018: 189 , 192.

TYPE SPECIES: Stenochrus valdezi Monjaraz- Ruedas, 2012 [= Troglostenochrus valdezi ( Monjaraz-Ruedas, 2012) , comb. nov.], type species, here designated.

DIAGNOSIS: Troglostenochrus , gen. nov., may be separated from other hubbardiid genera by the following combination of characters. Cheliceral movable finger serrate, with multiple teeth; single guard tooth at end of serrula; setal group G3 with G3-3 setae situated anteriorly (fig. 13I). Propeltidium anterior process with two anterior setae (one posterior to the other) and three pairs of dorsosubmedian setae (fig. 11A); corneate eyes absent. Metapeltidium entire. Tegument without clavate setae. Pedipalps homeomorphic; trochanter with mesal spur, apical process long, projected and fan-shaped (fig. 7I); femur Fv 1 and Fv 2 setae spiniform, Fvr 1–4 setae present (Fvr 1–3 setae in Troglostenochrus palaciosi ( Reddell and Cokendolpher, 1986) , comb. nov.); patella with four acuminate Pe setae and four feathered Pm setae; tibia setal formula 3-3-4 (Ter-Tmr-Tir) (fig. 14D). Leg IV femur anterodorsal margin produced at ca. 90° angle. Opisthosomal tergite II with one pair of setae (Dm). Opisthosomal segments IX–XII not elongated; XII (♂) without posterodorsal process. Pygidial flagellum (♂) bulbous, trilobed, without dorsal depressions (fig. 23G–I), with pair of dorsosubmedian, rounded projections; flagellum (♀) with two annuli (fig. 24G–I). Spermathecae (♀) with two pairs of lobes; lateral lobes ca. 3/4 the length of median lobes, linear, with apex directed laterally; median lobes inverse J-shaped with apex directed laterally; lobes unsclerotized apically and without bulbs; median lobe bases anterior to lateral lobe bases, with duct openings along entire length (fig. 9F); chitinized arch hastate, with curved anterior branch, and lateral tips extremely projected and tapering; gonopod long and narrow.

COMPARISONS: Species of Troglostenochrus , gen. nov., resemble species of Cokendolpherius Armas, 2002 in the trilobed pygidial flagellum and robust pedipalps, with a projected, conical apical process of the pedipalp trochanter, of the male, and the three pygidial flagellomeres and horizontal bracket shape of the chitinized arch of the spermathecae, of the female. However, Troglostenochrus bears three pairs of dorsal setae on the propeltidium, whereas Cokendolpherius bears two pairs, and females of Troglostenochrus possess both Vm 2 and Dl 4 setal pairs on the pygidial flagellum, which are absent in Cokendolpherius , and the spermathecal lobes are considerably longer in Troglostenochrus than in Cokendolpherius .

Species of Troglostenochrus resemble species of Baalrog , gen. nov., in the shape of the female spermathecae, in which the lateral lobes are reduced, and the lateral tips projected. However, the lateral lobes are considerably longer and wider in Troglostenochrus than in Baalrog , and the anterior branches of the chitinized arch are present and curved in Troglostenochrus , but absent in Baalrog .

ETYMOLOGY: The generic name is a compound word derived from troglo (Greek, “hole”), referring to the troglomorphic species included in the genus, and “ Stenochrus ,” the genus in which its two species were formerly accommodated. It is masculine in gender.

INCLUDED SPECIES: Troglostenochrus palaciosi ( Reddell and Cokendolpher, 1986) , comb. nov.; Troglostenochrus valdezi ( Monjaraz-Ruedas, 2012) , comb. nov.

DISTRIBUTION: Troglostenochrus , gen. nov., is known from only two disjunct localities in the states of Guerrero and Chiapas, southern Mexico. Presumably, the genus extends across the entire Sierra Madre del Sur in Oaxaca and the Sierra Chiapas, although extensive searching in the caves of Chiapas have thus far failed to collect additional species (fig. 4).

NATURAL HISTORY: The known species of Troglostenochrus , gen. nov., are strictly cavernicolous, inhabiting the dark zone of caves, and have not been collected on the surface. Mayazomus loobil Monjaraz-Ruedas and Francke, 2015 , was collected outside the cave inhabited by T. valdezi , comb. nov.

REMARKS: Species of Troglostenochrus , gen. nov., closely resemble species of Cokendolpherius , endemic to Cuba. Unfortunately, no samples of Cokendolpherius were available for DNA isolation and attempts to collect fresh material of T. palaciosi , comb. nov., were unsuccessful (the cave was never found). Nevertheless, the morphological characters and simultaneous phylogenetic analyses (fig. 6) unequivocally support the placement of T. palaciosi within Troglostenochrus . The acquisition and analysis of DNA sequence data from Cokendolpherius are needed to test its relationship to Troglostenochrus .

Figures

FIG. 4. Map of southern Mexico, plotting known locality records for the short-tailed whipscorpion genera Heteroschizomus Rowland, 1973, stat. rev. (circles), and Troglostenochrus, gen. nov. (squares) (Schizomida: Hubbardiidae Cook, 1899), based on data from museum collections and the literature.