Clubiona japonica

Dankittipakul, Pakawin & Singtripop, Tippawan, 2008, Five new species of the spider genus Clubiona Latreille (Araneae: Clubionidae) from Thailand, Zootaxa 1747, pp. 34-60: 36

publication ID 10.5281/zenodo.181670

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scientific name

Clubiona japonica


The japonica  -group

Diagnosis. Infrageneric classification as proposed by Mikhailov (1995) was defined on the base of the Palaearctic fauna. Deeleman-Reinhold (2001) provided a further discussion of species-group limits and relationships on a regional scale, with focus on the Oriental species. Representatives of the japonica  -group are easily recognized by general appearance in which carapace and dorsum of opisthosoma are marked with a dark color pattern ( Figs 1View FIGURE 1, 5, 8View FIGURES 5 – 10, 34View FIGURES 34 – 40, 41View FIGURES 41 – 47, 48View FIGURES 48 – 51, 55View FIGURES 55 – 60). For the Thai species treated below there are three teeth situated on promarginal margin of cheliceral fang grooves, middle one largest, and two separated small teeth on retromargin. Male palp is provided with unbranched tibial apophysis ( Figs 7, 10View FIGURES 5 – 10, 12, 16View FIGURES 11 – 19); tegulum distinctly with sinuate sperm duct ( Figs 6, 9View FIGURES 5 – 10, 11, 15View FIGURES 11 – 19, 20, 22View FIGURES 20 – 23); and the conductor sclerotized ( Figs 9View FIGURES 5 – 10, 22View FIGURES 20 – 23). Females are recognized by epigynal atrium situated anteriorly ( Figs 13, 17View FIGURES 11 – 19, 24View FIGURES 24 – 29); genital orifices located in a rebordered groove ( Figs 2View FIGURES 2 – 4, 39View FIGURES 34 – 40); and membranous bursae being slightly larger than anterior spermathecae ( Figs 4View FIGURES 2 – 4, 18View FIGURES 11 – 19, 25View FIGURES 24 – 29).

Taxonomic remarks. Based on examination of the Southeast Asian fauna, the japonica  -group can be further divided into two different lineages. Members of a complex including C. melanosticta Thorell  , C. melanothele Thorell, 1895  , C. suthepica  sp. n., C. charleneae Barrion & Litsinger, 1995  , and C. scandens Deeleman-Reinhold, 2001  seem to form a monophyletic linage based on the possession of a beak-shaped conductor that is transversely aligned at the apical portion of the bulb ( Figs 9View FIGURES 5 – 10, 22View FIGURES 20 – 23). A somewhat similar character has evolved independently in C. picturata Deeleman-Reinhold, 2001  and related species i.e., C. filicata  O. P.- Cambridge, 1874, C. biembolata Deeleman-Reinhold, 2001  , C. campylacantha  sp. n., C. octoginta  sp. n., C. submaculata (Thorell, 1891)  . The monophyly of this group is supported by the possession of a conspicuous apical appendage on the tegulum which is considered as a transformation of the very long, filiform conductor that fuses with the reduced embolus ( Figs 6 –7View FIGURES 5 – 10, 11–12, 15–16View FIGURES 11 – 19, 20–21View FIGURES 20 – 23, 30– 32View FIGURES 30 – 33).

The rather strange vulvae of the japonica  -group form one of the most striking features of the taxon. However, the female genitalia of the included species are all very similar, to the extent that species identification on female genitalia alone may well be impossible. The epigyne is characterized by the atrium and atrial margin. In the Thai species described below, the atrium is situated anteriorly on the epigynal plate. The anterior and lateral atrial margins are often rebordered ( Figs 13, 17View FIGURES 11 – 19, 24View FIGURES 24 – 29). The genital orifices are near the middle part of the epigyne, situated close to the base of rebordered basolateral atrial margin ( Fig. 2View FIGURES 2 – 4) and lead to the short insemination ducts of the vulva ( Figs 2–3View FIGURES 2 – 4). The insemination ducts are membranous and almost indistinct; they connect to the anterior portion of the membranous bursae situated posteriorly ( Fig. 3View FIGURES 2 – 4). The spermathecae are strongly elongated and highly convoluted ( Fig. 4View FIGURES 2 – 4). The spermathecae comprise three distinct parts: spermathecal heads (= an additional appendix of insemination ducts according to Deeleman-Reinhold 2001), stalks and bases ( Fig. 4View FIGURES 2 – 4). Spermathecal heads are elongate extensions of the spermathecae that connect to the anterior part of the spermathecal stalks; they expand laterally, gradually narrowing towards terminal ends which are dilated and covered with numerous apical pores ( Figs 14, 19View FIGURES 11 – 19, 27View FIGURES 24 – 29). Spermathecal stalks are elongated, often parallel tubular structures. The spermathecal bases are indistinguishable from the stalks and encircle around the fertilization ducts. The fertilization ducts are relatively small and arise from the posteriolateral end of the spermathecae. It seems that obliquely directed tubular spermathecal heads with distally dilated portions, spermathecal bases encircling fertilization ducts and posteriorly situated membranous bursae are plesiomorphic within the japonica  -group. The insemination ducts referred by Deeleman-Reinhold (2001) are here considered part of spermathecae. The insemination ducts of the Thai species described below are distinctly short, entirely membranous ( Fig. 3View FIGURES 2 – 4) and lead to posterior bursae that open directly to the anterior spermathecae.