Scotinoecus Simon, 1892

T, Duniesky Rios & Goloboff, Pablo A., 2012, New species of Chilean Hexathelidae (Araneae, Mygalomorphae), Zootaxa 3422, pp. 32-51 : 33-34

Scotinoecus Simon, 1892

Scotinoecus Simon, 1892: 188 .

This genus is endemic of southern South America, with two described species, S. cinereopilosus ( Simon 1889) and S. fasciatus Tullgren, 1901 . Simon described the female of S. cinereopilosus , from Valdivia , Región X, Chile; 13 years later, Tullgren described the female of S. fasciatus , from Tierra del Fuego and Puerto Gallegos, Argentina; the two species remained known only from females for almost 70 years, until Schiapelli and Gerschman (1968) revised the genus describing the male of S. fasciatus . Subsequently, Calderón (1973) described a male from Valparaiso, Región V, attributing it to S. cinereopilosus , pointing out differences between this male and that of S. fasciatus . The low dispersal capabilities of these spiders (see Raven, 1980) and the enormous geographic distance between the female type and the male described by Calderón (1973) strongly suggest that the identification made by Calderón was in error.

In this paper, the male described as S. cinereopilosus was collected together with females, much closer to the type locality; those females are also very similar to those collected at no more than 15 km from the type locality of the species, allowing us to reliably establish the present association between males and females.

The most reliable differences between the species of Scotinoecus recognized here are in morphological characters (leg shape and spination, number of spigots in the ALS). The female spermathecae have complex and convoluted ducts, with variation in details even between specimens of the same locality (e.g., Figs 21–22 , from the same locality, differ in the inner branch of the spermathecae). Other mygalomorphs with many spermathecal receptacles often present minor differences in the number or shape of receptacles of both sides (e.g., Stenoterommata platense Holmberg, 1881 ; see Goloboff, 1982, 1995); presumably, receptacles with thin, weak ducts may easily get broken during moults, producing minor differences in successive moults of the adult female. A conservative approach is followed here, considering as conspecific those females with general agreement in their morphology despite minor differences in spermathecal shape. Future work may well reveal that some of the species recognized here represent in fact more than one species.

Type species. Hexathele cinereopilosa Simon, 1889 .

Diagnosis. Females of Scotinoecus differ from those of Mediothele by the labium and maxillae having many cuspules, the paired bilobate spermathecae, the STC with more numerous and longer teeth, longer (PLS) spinnerets, the ALS two-segmented as long as or shorter than PMS, and the more numerous spigots on the spinnerets (with 30–50 spigots per PLS article, as opposed to 10–30 in Mediothele ). Several of these characters (STC teeth, spinneret length, and spigot number) are possibly associated with building sheet-webs.

Habits. All species of Scotinoecus , except S. fasciatus , spin a sheet web similar to that of ischnotheline diplurids. Vellard (1958) reported having collected specimens of S. fasciatus in burrows, with no webs.

Monophyly. It differs from Mediothele in lacking its synapomorphies; Scotinoecus might thus well be paraphyletic in terms of that genus. The length of the spinnerets in S. fasciatus , together with the burrowing (rather than webbing) habits, tenuously suggest that that species might be more closely related to Mediothele than it is to the other Scotinoecus . However, as those characters are highly variable in other groups of mygalomorphs, they provide only weak evidence of relationships; consequently, no nomenclatorial action is taken here regarding S. fasciatus .

Figures

FIGURES 16 – 24. Scotinoecus, spermathecae. 16 – 18. S. cinereopilosus. 19 – 20. S. ruiles sp. nov. 19 holotype, 20 variation (Talca: Gil de Vilches). 21 – 24. S. major sp. nov. 21 holotype, 22 – 24 variation. 22 (San Antonio: Quebrada Córdoba, 5 km E. El Tabo), 23 – 24 (Linares: El Peñasco – 21 km. SE Linares ~ 200 m. a. s. l.).