Vietnagone, Tanasevitch, 2019

Tanasevitch, Andrei V., 2019, A new genus and two new species of linyphiid spiders (Arachnida: Araneae) from Vietnam, Raffles Bulletin of Zoology 67, pp. 129-134 : 129-130

Vietnagone , new genus

Type species. Vietnagone silvatica , new species.

Etymology. The generic name is a combination of two words: “Vietna”, from part of the name of the country of origin of its type species, while the end part refers to the generic name Erigone ; the gender is feminine.

Diagnosis. The genus contains erigonines with a total length of 1.50–1.78, which are characterised by the following combination of somatic and genital characters:

1) carapace unmodified in both sexes, cephalic pits absent (see Figs. 1, 2 );

2) chelicerae strong, a mastidion absent;

3) chaetotaxy formula: 2.2.1.1; all metatarsi with a trichobothrium; TmI 0.39–0.44;

4) palpal tibia relatively large, modified (see Figs. 7–9 );

5) median membrane strongly reduced (see Fig. 7 );

6) distal suprategular apophysis moderately developed (see Fig. 10 );

7) radix small, convector present;

8) embolus whip-shaped, looped (see Fig. 11 );

9) abdomen with a pattern in both sexes (see Figs. 1–3 );

10)epigyne without a distinct cavity (see Figs. 3 , 12 ).

Taxonomic remarks. Based on the male palp conformation and somatic characters (see items 2–4, 7 from the list above), the new genus is similar to Gongylidioides Oi, 1960 , but distinguished by the unusual shape of the palpal tibia ( Figs. 7–9 cf. Figs. 1G, 2H, 3H, 5G, 6G in Tu & Li, 2006), the peculiar structure of the convector, which in Vietnagone , new genus is divided into two parts (vs. unipartite in Gongylidioides , see Tu & Li, 2006, Song & Li, 2010), as well as by the structure of the epigyne, namely the fused lateral walls covering the epigynal cavity (vs. spaced lateral walls in Gongylidioides , Fig. 12 cf. Figs. 1H, 2I, 3I, 4C, 6H in Tu & Li, 2006).

Species included. The genus contains two species: Vietnagone silvatica , new species (the type species) and V. rugulosa ( Song & Li, 2010) , new combination, ex Gongylidium Menge, 1868 .

Distribution. Southeastern Tibet ( Song & Li, 2010) and northern Vietnam.

Figures

Figs. 1–6. Habitus of Vietnagone silvatica, new species (1–3) and Nasoonaria pseudoembolica, new species (4–6). 1, 4, male holotype; 2, 3, 5, 6, female paratype; 1, 2, 4, 5, dorsal view; 3, 6, ventral view.

Figs. 7–13. Details of palpal and epigynal structure of Vietnagone silvatica, new species. 7–10, male holotype; 12, 13, female paratype. 7, left palp, retrolateral view; 8, 9, palpal tibia, prolateral and dorsal views, respectively; 10, distal suprategular apophysis, lateral view; 11, embolic division; 12, 13, epigyne, ventral and dorsal views, respectively.