Eusarcus minutus ( Sørensen, 1884 ) Acosta & Guerrero, 2021

Acosta, Luis E. & Guerrero, Elián L., 2021, The missing Eusarcus: generic relocation of Pucrolia minuta, with synonymic notes (Opiliones: Laniatores: Gonyleptidae), Zootaxa 4990 (3), pp. 587-590 : 588-589

Eusarcus minutus ( Sørensen, 1884) comb. nov.

Pachylus minutus Sørensen 1884: 643 . Type series: eight specimens from “Monte Rita” (MR) in Paraguay and 28 individuals from “Riacho del Oro” (RO), Argentina, all male and female syntypes. A part of the type series was detected in several institutions and examined: ZMUC (17 specimens from RO, 1 from MR), ZMB (2 specimens from RO), BMNH (2 specimens from MR). urn:lsid:zoobank.org:act:D93DBB9B-A3DC-474A-9510-E49A97073908

Pucrolia minuta: Sørensen 1895: 3 ; Roewer 1913: 16, fig. 1; Ringuelet 1959: 375, Pl. 2, fig. 6; Kury 2003: 188 [complete synonymy].

Pachylus gracilipes Canestrini 1888: 107 , Pl. 9, figs. 4, 4a-d. Type not found, presumably one female holotype from Resistencia , Chaco ( Argentina). urn:lsid:zoobank.org:act:E439AEC6-9BD6-431C-9A42-B8F39E4E6AC0 . Syn. nov.

Pucrolia gracilipes: Roewer 1913: 17 (Unsichere Art! = species uncertain); Ringuelet 1959: 373 (species inquirenda); Kury 2003: 188 (species inquirenda).

The general habitus of Eusarcus minutus comb. nov. ( Fig. 1A ) resembles closely most species in the genus. The main shared features include the three well-developed paracheliceral frontal apophyses, the shape and curvature of the prolateral apophysis on coxa IV of males, the triangular, short, blunt prolateral apophysis on the male trochanter IV, and male femur IV with prolateral and retrolateral rows of apophyses and two distinct ventroapical ones ( Hara & Pinto-da-Rocha 2010). Unlike most Eusarcus species , which typically bear a median conic apophysis on the scutal area III, E. minutus lacks any armature on the scutum, a feature shared with a few other species, like e.g. E. sergipanus Hara & Pinto-da-Rocha, 2010 , E. gemignanii ( Mello-Leitão, 1931) and E. uruguayensis ( Ringuelet, 1955) . In addition, the ocular mound of E. minutus is armed by a single apophysis ( Fig. 1A ), instead of the paired armature most frequent in genus Eusarcus ( Hara & Pinto-da-Rocha 2010). The referred character states were used by Ringuelet (1959) to separate Pucrolia from Eusarcus . The tarsal formula 5-6-6-6 of the nominal genus Pucrolia (of little help) is shared with E. gemignanii , E. grumani H. Soares, 1966 and E. uruguayensis . Finally, the male genitalia of Eusarcus minutus ( Fig. 1B–C ) consistently match the descriptions of those of most Eusarcus species (cf. Hara & Pinto-da-Rocha 2010).

As for the largely questioned Pucrolia gracilipes , it is to be considered a junior synonym of E. minutus . The type material of the former is presumably lost ( Guariento et al. 2018), but drawings and description given by Canestrini (1888: 107, Pl. 9, figs. 4, 4a-d) clearly show a female E. minutus . The type locality of P. gracilipes (Resistencia, Chaco province, Argentina) is placed in middle of the geographic range of E. minutus (cf. Ringuelet 1959).

Figures

FIGURE 1: Eusarcus minutus (Sørensen) comb. nov. A: Habitus in dorsal view, male from General Paz, Corrientes province, Argentina (LEA 000.422), scale 1 mm; B-C: Distal end of penis, male from Las Gamas, Santa Fe province, Argentina (MACN), B: dorsal view, C: lateral view, scale 0.1 mm.