Cheiracanthium truncatum Thorell 1895

Cheiracanthium truncatum (Thorell, 1895) Figs 10–13 Eutittha truncata Thorell, 1895: 48; description of female (provisionally considered female of gracilipes). Type material. Holotype: Ƥ, MYANMAR, Yangon Division: Yangon, leg. E. Oates (NHML). Original label: / Eutittha; truncata Thor.; an = Ƥ E. gracilipes?; Rangoon (Burma); Oates/. Old material. MYANMAR, Kayin Division: Palon, leg. L. Fea, 1885–1889 (MSNG): 1Ƥ (misidentified). Original label: / Eutittha; melanostoma Thor.; Burmania: Palon; Fea/. Remarks. The taxonomic status of E. truncata is intertwined with that of E. gracilipes. The female of E. truncata was provisionally identified by Thorell (1895) as E. gracilipes. Thorell seemed almost uncertain about his placement; he also provided a remark indicating that the female designated as E. gracilipes should be named as E. truncata, provided that it later turns out to be a different species. This female is regarded here as a valid taxon and separated from that of E. gracilipes, which is considered a junior synonym of C. insigne [based only on the male types], until the true conspecific female of C. insigne is discovered and formally redescribed. See also C. insigne for detailed discussion. Upon examination, a female labelled E. melanostoma (from Palon, identified by Thorell and deposited in MSNG; Fig. 12) neither agrees with the original description nor is identical to the type specimens of C. melanostomum (Thorell, 1895) to any degree. This female has proved to be E. truncata (Fig. 10). The following species probably belong to C. truncatum on the basis of their genitalic structures: C. fibrosum Zhang, Hu & Zhu, 1994 from China and C. unicum Bösenberg & Strand, 1906 from China, Korea, Japan and Laos. The slight genitalic differences detected between females of these two species and that of C. truncatum (Thorell, 1895) are considered intraspecific variation. Much larger samples would be needed to corroborate these slight differences as species-specific rather than as individual variation. Males of C. fibrosum and C. unicum are very similar and can be easily recognized by the peculiar shape of the retrolateral tibial apophysis, which is provided with a triangular dorsal hump, in combination with the possession of a sigmoid-shaped median apophysis on the tegulum and an elongate, slender spur on the dorsal side of the male palpal tibia. At this stage, synonymizing these two species with C. truncatum is inappropriate, pending the discovery of the true conspecific male of C. truncatum from Southeast Asia. There is a great hope that additional new material, particularly the conspecific male of C. truncatum, will be found in the near future and subsequently confirms the proposed taxonomic status of these species. Diagnosis. Females of C. truncatum are easily recognized by the circular sclerotized plate which is situated on a membranous epigynal atrium, in combination with a pair of pyriform spermathecae and heavily sclerotized insemination ducts arranged in an invert V-shaped (Figs 10, 12). Distribution. Burma (Rangoon and Palon) and presumably Laos, China, Korea and Japan.

Topic: Spider Taxonomy and Behavior Studies
Subfield: Genetics
Field: Biochemistry, Genetics and Molecular Biology
Domain: Life Sciences