Arauchemus, Ott, Ricardo & Brescovit, Antonio Domingos, 2012

Ott, Ricardo & Brescovit, Antonio Domingos, 2012, Arauchemus, a new spider genus of the Echemus group (Araneae: Gnaphosidae: Echeminae) from Araucaria Forest areas in southern Brazil, with notes on habitat preferences and phenology, Zootaxa 3339, pp. 44-56 : 45-47

publication ID	https://doi.org/ 10.5281/zenodo.209775
DOI	https://doi.org/10.5281/zenodo.6170508
persistent identifier	https://treatment.plazi.org/id/CA0387F0-380A-FFD9-458F-F84F52CEFA68
treatment provided by	Plazi
scientific name	Arauchemus
status	gen. nov.

Treatment

Arauchemus View in CoL gen. nov.

Type species. Arauchemus graudo sp. nov.

Etymology. Arauchemus is a contraction between Araucaria and Echemus . Gender is masculine.

Diagnosis. Species of this genus can be recognized as belonging to the “ Echemus group” ( Murphy, 2007) by the pale abdomen, presence of abdominal dorsal scuta in males, the typical dentition with three teeth at PM and one at RM ( Fig. 6E View FIGURES 6 A – H ) and by the larger AME ( Figs 2A View FIGURES 2 A – G , 3A View FIGURES 3 A – G ). Males of Arauchemus differ from those of all other genera of the Echemus group by the presence of several thorn-like processes at distal portion of a very robust male embolus ( Figs 4C View FIGURES 4 A – H , 6C View FIGURES 6 A – H ); females by the small and rounded spermathecae with copulatory ducts posterior to the atrium and to the copulatory openings, forming some 2–3 large rounded to oval sections almost as large as the spermathecae in diameter ( Figs. 2G View FIGURES 2 A – G ; 3G).

Note. The placement into Echeminae (sensu Platnick & Shadab, 1976) is justified by the pectinate tarsal claws ( Figs 4G View FIGURES 4 A – H , 5G View FIGURES 5 A – H ), toothed cheliceral promargin ( Fig. 6E View FIGURES 6 A – H ) and procurved posterior eye row ( Figs 2A, D View FIGURES 2 A – G ; 3A, D). Platnick & Shadab (1976) would consider for Echeminae only the genera with strong procurved eye row (not exactly the case of Arauchemus species, which presents less conspicuously procurved eye rows) but we considered the placement into this subfamily as the more adequate option. Based on a recent definition of Murphy (2007: 50) there is no doubt that the herein proposed new genus can be regarded as belonging to the Echemus group, since this species posses pale abdomen and developed scutum at males. The new genus is very close to Echemus by the presence of an anterior hood on the female epigynum ( Figs 2F View FIGURES 2 A – G , 3F View FIGURES 3 A – G ), small spermathecae and copulatory ducts of almost the same diameter as spermathecae ( Figs 2G View FIGURES 2 A – G ; 3G). However, the placement of the spermathecae closer to the median body line in Arauchemus ( Figs 2F, G View FIGURES 2 A – G ; 3F, G) is different from the type species of Echemus , E. angustifrons (Westring 1961) , in which the spermathecae are located far apart from each other (see Platnick, 1976:3, figs 3, 4; Murphy, 2007: 349). In E. angustifrons , also differing from Arauchemus , the bulb of male palp present a clear division, with the median apophysis placed well distally. The widely different morphologies of the male palpal bulb in Echemus species suggests that it does not constitute a monophyletic group as currently delimited (e.g., the very divergent morphology of palp in E. angustifrons and E. giaii Gerschman & Schiapelli 1948 ). Otherwise the embolus in the Echemus group is usually very slender (except in the genus Micythus Thorell 1897 ; see Murphy, 2007: 365, but in this one the female external genitalia is quite different from Arauchemus ).

Description. Total length 3.45–7.40. Yellowish-brown to orange-brown colored spiders. Cephalothorax oval, sulcated posteriorly, covered with weak setae (denser and stronger at area between pars cephalica and pars thoracica); thoracic grove short and narrow, longitudinal, at level of second and third coxae. Anterior eye row recurved, posterior eye row slightly procurved; AME largest, surrounded by darker tegument; AME, ALE and PLE rounded, PME smaller and slightly oval ( Figs 2A, D View FIGURES 2 A – G ; 3A, D). Clypeus low, around AME radius. Chelicerae with three teeth at PM and one at RM. Endites longer than wide. Labium triangular, slightly elongated, truncated distally. Sternum broad and rounded anteriorly, narrowing posteriorly, not extending posterior of coxae IV ( Fig. 3E View FIGURES 3 A – G ). Leg formula 1423; all femora with dorsal spines; tibia and metatarsus of legs III and IV heavily spinose, same segments of legs I and II much less spinose; tarsal scopula inconspicuous; preening brush distoventral at metatarsi III and IV ( Figs 2B View FIGURES 2 A – G , 3B View FIGURES 3 A – G , 4H View FIGURES 4 A – H , 5H View FIGURES 5 A – H ); plumose setae present on leg and palp articles ( Fig. 4D View FIGURES 4 A – H ). Trichobotria base with 4–6 ridges ( Figs 4E View FIGURES 4 A – H , 5C View FIGURES 5 A – H ). Tasal organ rounded, slightly elevated and with oval aperture ( Figs 5B View FIGURES 5 A – H , 6H View FIGURES 6 A – H ). Claws pectinate, with long teeth; claw tuffs formed by elongated and flattened hairs ( Figs 4G View FIGURES 4 A – H ; 5A, G). Abdomen grayish, elongated; frontal area covered with longer setae; anterodorsal scutum in males covered with needle-like and branched plumose setae ( Fig. 6F View FIGURES 6 A – H ), scutum absent in females, needle-like and plumose setae present at same area. Posterior median spinnerets with large ampullar fusulas ( Figs 5D, E View FIGURES 5 A – H ). Male palp with small triangular retrolateral apophysis ( Figs 1B, 1D View FIGURES 1 A – D , 2C View FIGURES 2 A – G , 3C View FIGURES 3 A – G , 4F View FIGURES 4 A – H , 6D View FIGURES 6 A – H ); robust and somewhat flattened embolus, distally covered with thorn-like processes, conductor lamellar and membranous, median apophysis hook-shaped ( Figs 1A–D View FIGURES 1 A – D ; 4A–C; 6A–C). Female palp with pectinate claw ( Fig. 5F View FIGURES 5 A – H ). Epigynum with single anterior atrial hood, copulatory openings oblique, slit-like, atrium widened anteriorly ( Figs. 2F View FIGURES 2 A – G , 3F View FIGURES 3 A – G ); spermathecae and copulatory ducts posterior to the atrium and copulatory openings; spermathecae small, rounded, very closed together; copulatory ducts coiled, forming some 2–3 large rounded to oval sections which are almost as large as spermathecae in diameter ( Figs. 2G View FIGURES 2 A – G ; 3G).