Abstract
A new genus and species of spider (Araneae, Linyphiidae, Erigoninae) from a tropical montane cloud forest of Mexico is described from both male and female specimens, Xim trenzado gen. et sp. nov. A phylogenetic parsimony analysis situates Xim gen. nov. as a distinct genus among the distal Erigoninae. Xim gen. nov. is sister to a clade including Ceratinopsis, Tutaibo and Sphecozone, but differs from those genera by having a high cymbium, large paracymbium, short straight embolus, male cheliceral stridulatory striae widely and evenly spaced, both sexes with a post-ocular lobe, male with two series of prolateral macrosetae on femur I, and the female by having strongly oblong, u-shaped spermathecae.
Highlights
Hoffmann (1976) enumerated 18 genera and 67 species for the family Linyphiidae Blackwall, 1859 in Mexico
We describe a new spider genus and species of Erigoninae found in a tropical mountain cloud forest in Chiapas, Mexico
Xim gen. nov. differs from Ceratinopsis by lacking trichobothria on the prolateral side of palpal tibia, by having a retrolateral tibial apophysis (Fig. 2C, F) and the dorsal plate of epigynum with an anterior lobe flush with the ventral plate (Fig. 5A–B, G); from Tutaibo by lacking a cymbial basal excavation and a tegular sclerite on the anterior part of the tegulum, by having a cymbium retrolateral groove (Fig. 2C, F–H), an embolic membrane (Figs 2E, H–I, 3B), copulatory ducts not encapsulated (Fig. 5C–F, H) and male lacking a proximal dorsal macroseta on the tibiae I and II; from Sphecozone by having a paracymbium (Figs 2A–F, 3A), a cymbial retrolateral groove (Fig. 2C, F–H), by lacking a cymbial basal excavation, and by lacking an epigynal atrium
Summary
Hoffmann (1976) enumerated 18 genera and 67 species for the family Linyphiidae Blackwall, 1859 in Mexico. 24 genera and 105 species of Linyphiidae are cited from Mexico (Banks 1898; Chamberlin 1924; Gertsch & Davis 1937, 1946; Dondale 1959; Millidge 1980, 1987; Prentice & Redak 2013; WSC 2020) whereas the rest of North America (Canada and USA) has 174 genera and 937 species (Draney & Buckle 2017). Miller (2007) reviewed the taxonomy of the Erigoninae Emerton, 1882 subfamily of Linyphiidae for the Neotropical region including 50 genera, of which he considered 39 as endemic to the Neotropics, but he stated that “Central American and Mexican linyphiids remain poorly. It could be due more to a scarcity of sampling of spiders in Mexico, or the need to sample in the adequate habitats for this family, as there are indications that in some tropical regions the linyphiids increase in abundance and richness with altitude (Russell-Smith & Stork 1994; Sørensen 2004; Miller 2007)
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