Erigone grandidens, Tu & Li, 2004

Tu, Lihong & Li, Shuqiang, 2004, A Preliminary Study Of Erigonine Spiders (Linyphiidae: Erigoninae) From Vietnam, Raffles Bulletin of Zoology 52 (2), pp. 419-433 : 420-422

Erigone grandidens , new species

( Fig. 2 )

Material examined. – Holotype - male, Gao Bao Village , Ha Jiang Province, Vietnam (017), 9 Dec.2000.

Paratypes – 2 females, same data as holotype ; 1 male, 1 female, Viet Lann Village , Ha Jiang Province, Vietnam (022), 10 Dec.2000 ; 1 male, 5 females, Viet Lann Village , Ha Jiang Province, Vietnam (023), 10 Dec.2000 ; 1 male, 2 females, Viet Lann Village , Ha Jiang Province, Vietnam (032), 10 Dec.2000 ; 1 male, Viet Lann Village , Ha Jiang Province, Vietnam (033), 10 Dec.2000 .

Diagnosis. – Male of this new species can be distinguished from other similar species by the following combination characters: small patella apophysis (PA), tibia without ventral tooth, terminal apophysis (TA) bending downwards and the blunt posterior radical process (PRP) rolling upwards. Female may be recognized by the diamond shaped atrium.

Description of male. – Total length: 1.53. Carapace: 0.83 long, 0.60 wide. Abdomen: 0.73 long, 0.53 wide. Carapace ( Fig. 2A ): cephalic portion strongly elevated, along median line on posterior slope with three small teeth, each carrying hair. Clypeus straight under ocular area, and then slightly protruding. Thoracic portion with several teeth on each side and fine furrow along lateral margin. Eyes subequal, with black surroundings; AER recurved, intervals of anterior eyes equal to AMEr; PER straight, posterior eyes separated by about PMEd; ALE and PLE close together. Chelicerae ( Figs. 2B ) anterolaterally furnished with row of eight strongly curved teeth, fang groove with five or six promarginal and four retromarginal teeth. Lengths of legs: I 1.97 (0.60+ 0.67+ 0.40+ 0.30), II 1.84 (0.57+ 0.60+ 0.37+ 0.30), III 1.46 (0.43+ 0.50+ 0.30+ 0.23), IV 1.87 (0.60+ 0.60+ 0.40+ 0.27); tibia spines: 2-2-2-1; Tm I: 0.38; Tm IV absent. Sternum grayish brown. Abdomen gray.

Palp ( Figs. 2 E-G): Patella short, almost as long as tibia, patella apophysis (PA) small, triangular, shorter than diameter of patella. Tibia without ventral tooth, apical part strongly widened dorsal-ventrally, width (height) of widened part longer than length of tibia, dorsal apophysis (DTA) bifurcate in retrolateral view ( Fig. 2C ), but seen in dorsal view, translucent sclerite exists between two ends ( Fig. 2D ). Tibia trichobothria: one prolateral, two retrolateral. Embolic division ( Fig. 2H ): anterior radical process (ARP) long and curved, with four transversal membranous ridges outside and membranous margin anteriorly; terminal apophysis (TA) well developed and bending downwards; posterior radical process (PRP) large and blunt, rolling upwards.

Description of female. – Total length: 1.50. Carapace: 0.70 long, 0.47 wide. Abdomen: 0.90 long, 0.60 wide. Cephalic portion without rising. Chelicerae without anterolateral teeth, fang groove with six promarginal and five small retromarginal teeth. Lengths of legs: I 1.70 (0.50+ 0.57+ 0.33+ 0.30), II 1.60 (0.50+ 0.50+ 0.33+ 0.27), III 1.30 (0.40+ 0.37+ 0.30+ 0.27), IV 1.74 (0.57+ 0.57+ 0.33+ 0.27); tibia spines: 2-2-2- 1; Tm I: 0.38; Tm IV absent. Other somatic characters as in male.

Epigynum ( Fig. 2I ): very simple, slightly chitinized with fine transversal striation, more concave in posterior portion with tip turning up. Vulva seen in dorsal view ( Fig. 2J ) shows atrium somewhat diamond shaped, anterior portion covered by dorsal plate, posterior margin of dorsal plate curved, the middle part of two copulatory ducts convergent and anterior turning points (ATP) close to each other.

Etymology. – The specific name comes from the Latin grandidens (large tooth), referring to the chelicerae that are anterolaterally furnished with a row of conspicuous teeth.

Remarks. – This new species belongs to Crosby & Bishop’s (1928) psychrophila group of the genus Erigone . Several similar species had been recorded in Asia, include E. prominens Bösenberg & Strand, 1906 , E. ourania Crosby & Bishop, 1928 , E. koshiensis Oi, 1960 and E. bifurca Locket, 1982 . As described and illustrated by Holm (1977) and Oi (1960) respectively, the male palp of E. prominens and E. koshiensis has a longer patella (longer than tibia) and a conspicuous longer patellar apophysis (conspicuously longer than the diameter of the patella), and the tibia has a strong ventral tooth ( Fig. 3C ) (absent in E. grandidens ). Both terminal apophysis (TA) and posterior radial process (PRP) of embolic division in E. prominens plate-shaped and erected ( Fig. 3G ), whereas in the new species different as described above. The characters of embolic division in E. koshiensis are not clear. E. ourania is similar to the new species, with short patella as long as tibia and short patella apophysis almost as long as the diameter of patella, but it has a strong tibia ventral tooth and embolic division with a extremely long and slender anterior radical process (called median tooth by Crosby & Bishop) and a sharp posterior radical process (Crosby & Bishop, 1928: Figs. 63-65). Compared with the illustrations of E. bifurca provided by Locket (1982), it differs from the new species in the patella apophysis (longer and narrower), tibia (with a conspicuous ventral tooth), and the most importantly, the anterior radical process (ARP) (with a bifurcate apex, absent in the new species).

The epigynum and vulva of E. grandidens is similar to that of E. prominens , but differs in: 1) posterior portion of ventral plate narrow and concave in new species (wider and more convex in E. prominens ); 2) posterior margin of dorsal plate curved (almost straight in E. prominens ); 3) the middle part of two copulatory ducts convergent and anterior turning points close to each other (in E. prominens the middle part of two copulatory ducts are parallel and the anterior turning points separated). The atrium of E. ourania as illustrated by Wunderlich (1983) is hexagonal. Female genital structures of E. koshiensis , as illustrated by Oi (1960) and of E. bifurca , as illustrated by Locket (1982), lack details, but the vulva of E. koshiensis as depicted by Saito (1982) is almost same as in E. grandidens . While the characters of male palp of E. koshiensis provided by Oi (1960) show distinct differences with the new species as compared above, we believe the species described by Saito (1982) may be not E. koshiensis .

Distribution. – Known only from the type locality.

Figures

Fig. 2, Erigone grandidens, new species. A, carapace, lateral view; B, male left chelicera, frontal view; C, palpal tibia, retrolateral view; D, palpal tibia, dorsal view; E, left male palp, retrolateral view; F, left male palp, ventral view; G, left male palp, prolateral view; H, embolic division, ventral view; I, epigynum, ventral view; J, vulva, dorsal view. [Scale bars: 0.1mm].

Fig. 3, Erigone prominens Bösenberg & Strand, 1906. A, carapace, lateral view; B, male left chelicera, frontal view; C, left male palp, retrolateral view; D, left male palp, retrolateral view; E, left male palp, prolateral view; F, left male palp, ventral view; G, embolic division, ventral view; H, palpal tibia, dorsal view; I, epigynum, ventral view; J, vulva, dorsal view. [Scale bars: 0.1mm].