Tetrablemma thamin, Labarque, Facundo M. & Grismado, Cristian J., 2009

Labarque, Facundo M. & Grismado, Cristian J., 2009, Description of a new species of armored spider from Myanmar (Araneae: Tetrablemmidae), Zootaxa 2143, pp. 55-58 : 55-58

Tetrablemma thamin , n. sp.

( Figs 1–11 )

Type material: Male holotype and female paratype from Myanmar, Magwe Division, Shwesettaw Wildlife Reservation, N20°05’51.1”, E94°33’24.5”, elev. 450 m, deciduous forest, under rocks, 28.–29.IX.2003, leg. D. Ubick, deposited in CAS (CASENT 9017092). (Holotype voucher codes ARAMR 000301, preparation codes CJG-00119, FML-00574; paratype voucher codes ARAMR 000300, preparation codes CJG-00120, FML-00575).

Additional material examined: Same data as the types, 2 males, 8 females and one juvenile ( CAS; voucher codes ARAMR 000120, 125, 838, 862; preparation codes CJG-00116, CJG-00127, FML-00281–289).

Etymology: The specific name is a noun in apposition that refers to the thamin deer ( Cervus eldi thamin ), an endangered cervid typical of Myanmar, protected in the Shwesettaw Wildlife Reservation. The long and curved cheliceral horns of the males resemble the frontal branches of the horns of thamin males.

Diagnosis: Males of Tetrablemma thamin n. sp. resemble those of T. brevidens Tong & Li and T. magister Burger by the pear-shaped copulatory bulb and the shape of the embolus ( Fig. 1 ; Tong & Li 2008: figs. 5 G─H; Burger 2008: fig. 19). However, T. thamin n. sp. can be distinguished from both species by having two acute retrolateral processes at the base of the embolus instead of a blunt process or inconspicuous one respectively ( Fig. 3 ; Tong & Li 2008: fig. 5 F; Burger 2008: fig. 19). Also they can be distinguished by the shape of cheliceral horns ( Figs. 8 ─9; Tong & Li 2008: fig. 5 C; Burger 2008: figs. 15, 18), and the prosoma reticulated pattern, which in T. thamin n. sp. present some smooth areas, not as in the other two species. Females of T. thamin n. sp. resemble those of T. vietnamensis Lehtinen , T. brevidens and T. magister by their relatively large size, the pattern of abdominal scuta, the transverse furrows on the epigynal area ( Figs 2 , 11 ; Lehtinen 1981: figs 275, 286; Tong & Li 2008: fig. 5 D─E; Burger 2008: fig. 22, 25). T. thamin n. sp. can be distinguished from T. vietnamensis , T. brevidens and T. magister by its inconspicuous central vulval process ( Fig. 2 ) and by its shorter and broader postgenital ventral plate ( Figs 2 , 11 ).

Description. Male (CASENT 9017092): Total length 1.14. ALE>PLE, PLE separated by about one diameter; dorsal shield of prosoma covered with fine reticulated pattern, except in front and above the ocular areas, and in several thin smooth radial areas ( Figs 6, 8 ). Anterior hump of the clypeus without tubercles, but with a pair of setae. Cheliceral horns long, relatively narrow, tip pointing backwards ( Figs 8 ─9). Dorsal abdominal scutum long, oval, finely reticulate except by several sparse smooth rounded areas ( Fig. 6 ). All sclerotized integuments orange ( Fig. 6 ─7, 9). Palp: copulatory bulb pear-shaped; thread-like embolus with two acute retrolateral process at its base, and subterminal outlet ( Figs. 1 , 3 ).

Female (CASENT 9017092): Total length 1.18. Cephalic area horizontal, with acute process projecting posteriorly. AME>PLE, PLE separated by more than one diameter ( Fig. 10 , traces of PME visible by transparence); dorsal shield of prosoma with reticulate pattern similar as in male. Abdominal ventral scuta as in T. vietnamensis , T. brevidens and T. magister ( Lehtinen 1981: fig. 275; Tong & Li 2008: fig. 5 D; Burger 2008: fig. 22), but postgenital plate shorter and broader, epigynal area with shallow transverse furrows and a dark pit ( Fig. 11 ). Vulva: a single oval genital opening leading into a paired sclerotised copulatory ducts (Fig. 4); central vulval process inconspicous; inner vulval plate triangular with a central branch; seminal receptacles with folded cuticle ( Fig. 2 ). Color as in male.

Distribution. Only known from Myanmar.

Life history and habitat preferences. According to the labels, all the known specimens were found under stones, in a deciduous forest.

Remarks. The posterior position of the male eye group and convex clypeus suggest that Tetrablemma thamin n. sp. may belong to either subgenera Tetrablemma or Indonops ( Lehtinen, 1981) . The absence of modifications in the male first metatarsi or undulations on the copulatory bulb suggests that it may belong to the subgenus Indonops rather than Tetrablemma . Within Indonops , the presence of transverse epigynal furrows suggest that T. thamin n. sp. belongs to the marawula species group, which includes T. marawula Lehtinen , T. manggarai Lehtinen , T. mardionoi Lehtinen , T. vietnamensis , T. pulchoki Lehtinen , and probably the recently described T. brevidens and T. magister . The retrolateral processes at the base of the embolus suggest that this two latter species are closest to T. thamin n. sp.

Figures

FIGURES 3 ─ 4. Tetrablemma thamin n. sp. Genitalia. 3 male left palp, embolus detail, dorsal view (ARAMR 000120); 4 female genitalia, detail of genital opening, ventral view (ARAMR 000838). Abbreviations: (ARP) acute retrolateral processes, (SO) subterminal outlet. Scale bars: 150 µm; 220 µm.

FIGURES 1 – 2. Tetrablemma thamin n. sp. Genitalia. 1 male right palp, retrolateral view (ARAMR 000120); 2 female vulva, dorsal view (ARAMR 000125). Abbreviations: (ARP) acute retrolateral processes, (B) bulb, (E) embolus, (IVP) inner vulval plate, (PAP) pre-anal plate, (PVP) postgenital ventral plate, (S) seminal receptacle, (T) tibia, (Tf) transverse furrow. Scale bars: 100 µm.

FIGURES 6 – 11. Tetrablemma thamin n. sp. Preserved specimens. 6 – 9 male holotype (ARAMR 000301) (6 dorsal, 7 ventral habitus, 8 prosoma lateral, * in horn, 9 ditto, frontal). 10 – 11 female paratype (ARAMR 000300) (10 dorsal, 11 ventral habitus). Abbreviations: (PVP) postgenital ventral plate. Scale bars: 6 – 7 = 0.5 mm, 8 – 11 = 0.25 mm.