Diplura gymnognatha Bertkau, 1880

Drolshagen, Bastian & Bäckstam, Christian M., 2021, A taxonomic review of the mygalomorph spider genus Linothele Karsch, 1879 (Araneae, Dipluridae), Zoosystema 43 (10), pp. 163-196 : 190

Diplura gymnognatha Bertkau, 1880 comb. rev. nomen dubium

Diplura gymnognatha Bertkau, 1880: 21 , pl. 1, fig. 5. comb. rev.

Linothele gymnognatha – Raven 1985: 74.

TYPE MATERIAL. — Holotype. Brazil • ♀; Pedra do Açu ; E. Van Beneden leg; not located, presumably lost.

REMARKS

The original description ( Bertkau 1880) mentioned 11 cheliceral teeth and 20 maxillary cuspules. The description is confusing with regards to the legs: Bertkau (1880) mentioned the presence of ventral spines on tarsi, pseudo-segmented metatarsi, presence of a dense scopula on anterior tarsi and metatarsi, but divided scopula on posterior metatarsi. It seems like the terms metatarsi and tarsi were mixed in the original description. Bertkau further mentioned short spinnerets. The female genitalia are illustrated ( Bertkau 1880: Pl. 1, fig. 5) and resemble the shape observed in Linothele gaujoni , with long, tube-shaped stalks, as also reported for Trechona diamantina Guadanucci, Fonseca-Ferreira, Baptista & Pedroso, 2016 . The spermathecae of L. gaujoni and T. diamantina differ from the latter by the lack of lateral vesicles. It might have been hard to identify such details for Bertkau, but the type locality is also noticeably disjunct from the one of L. gaujoni .

According to Pedroso et al. (2008), who refer to Kury (2003), most of the arachnids collected during the Belgian mission to Brazil and described by Bertkau (1880) were deposited at IRSNB. Unfortunately, the holotype could not be located in IRSNB collection (L. Baert, pers. comm.) and might have been lost during WWII.

Bücherl et al. (1971) synonymized D. borgmeyeri with D. gymnognatha and provided variation data for D. borgmeyeri (CT = 12-14). They further added measurements for the opisthosoma (10.5) and a PLS: 8.9 (2.5, 2.6, 3.8). It becomes clear that these measurements do not match the ones provided for D. gymnognatha by Bertkau (1880), who reported the spinnerets (6.0) to be a lot shorter than the opisthosoma (10.0). Bücherl et al. (1971) stated they examined the epigastrium of 3 juvenile females, of which two lacked a spermatheca (= imm. male) and the only spermatheca found was rudimentary. Yet, they considered it to equal the illustration of the spermatheca of D. gymnognatha provided by Bertkau (1880). Contradictory to Bertkau (1880), who mentioned the presence of 20 maxillary cuspules, Bücherl et al. (1971) noted the absence of maxillary cuspules in D. borgmeyeri . Considering the possible lapsus in the first description of D. gymnognatha , the scopula on anterior tarsi and metatarsi was dense and possibly undivided. The fact that Bücherl et al. (1971) did not transfer D. borgmeyeri to Uruchus , as they did with D. fallax , indicates the scopula on all tarsi of D. borgmeyeri was divided.

As the holotype of D. gymnognatha is presumably lost since WWII, Bücherl et al. certainly did not examine it and the specimens they examined were not conspecific. As a result, the synonymy established by Bücherl et al. (1971) is herein rejected.

Bertkau (1880) neither mentioned the presence, or absence of a maxillary lyra for D. gymnognatha . In the same work, Bertkau (1880) proposed Thalerothele for T. fasciata Bertkau, 1880 without mentioning a lyra. Thalerothele was found to bear a lyra by Simon (1903), clearly indicating Berkau did not check for the presence of such a structure. Considering the possible lapsus, the description might match either Linothele , or Trechona .

As the absence of a lyra cannot be confirmed by original designation and the type is lost, the species cannot be placed in any diplurine genus with certainty. As a result, Linothele gymnognatha is transferred back to Diplura due to original designation and Diplura gymnognatha comb. rev. is considered a nomen dubium.