Cavisternum bom n. sp.

Ranasinghe, U. G. S. L. & Benjamin, Suresh P., 2018, Taxonomic descriptions of nine new species of the goblin spider genera Cavisternum, Grymeus, Ischnothyreus, Opopaea, Pelicinus and Silhouettella (Araneae, Oonopidae) from Sri Lanka, Evolutionary Systematics 2 (1), pp. 65-80 : 65

Cavisternum bom n. sp. Figs 1 A–G, 2 A–B

Type material.

Male holotype from Sri Lanka, Northern Province, Jaffna District, Mandaitivu FR, 09°36'26"N 79°59'5"E, 12m, litter; 20-22 September 2016; leg. S. P. Benjamin et al. (IFS_Oon_405) (ZFMK).

Paratype.

1 female; same locality data (IFS_Oon_406) (ZFMK).

Diagnosis.

The male of Cavisternum bom n. sp. resembles males of C. attenboroughi Baehr & Raven, 2013 by the sternal concavity occupying about half the sternal length (Fig. 1D), but differ in having an oval-shaped cymbium-bulb complex with a tube-shaped embolus (Fig. 2A). Females are diagnosed by the epigastric area with narrow copulatory ducts as in C. digweedi Baehr, Harvey & Smith, 2010, but differ in having a thin semicircular rim, which is widened anteriorly and narrowed posteriorly (see arrow in Fig. 2B).

Etymology.

This specific name is a noun in apposition named after “Bom” a magnificent goblin in the story of "The Goblins Looking-Glass" by Enid Blyton (1947).

Description.

Male: Total length 1.10 (Carapace, L: 0.40, W: 0.28. Abdomen, L: 0.70, W; 0.32). Coloration: carapace pale orange, sternum pale orange, mouth parts orange-brown, abdominal scuta pale orange, legs yellow, palps pale orange. Carapace ovoid in dorsal view (Fig. 1A), slightly elevated, anteriorly narrowed to half its maximum width, with rounded posterolateral corners, pars cephalica slightly elevated, lateral margin rebordered and surface smooth (Fig. 1C). Clypeus straight in front view, ALE separated from edge of carapace by less than their radius. Six eyes, well developed, ALE largest, circular, PME oval, PLE circular, posterior eye row straight from above, procurved in front view. ALE–ALE separated by less than ALE radius, ALE–PLE separated by less than ALE radius, PME–PME touching, PLE–PME touching. Sternum as longer than wide with concave field of clavate setae occupying about half the sternal length (Fig. 1D). Cheliceral fangs widened. Labium rectangular, not fused to sternum. Endites not excavated distally. Abdomen elongated-oval (Fig. 1B). Dorsal scutum sclerotized, covering full length of abdomen, pale orange, without color pattern, not fused to epigastric scutum. Epigastric scutum sclerotized, ventrally plain, book lung covers large, ovoid, without setae, pedicel tube short, ribbed. Epigastric furrow separates epigastric scutum from postepigastric scutum. Postepigastric scutum long, almost rectangular, covering about more than 3/4 of abdominal length, fused to epigastric scutum, with long posteriorly directed lateral apodemes. Spinneret scutum present as an incomplete ring. Leg spines absent. Genitalia: Palp of normal size, not strongly sclerotized, proximal segments, cymbium, bulb and embolus yellow. Cymbium ovoid in dorsal view, completely fused with bulb without visible seam, bulb oval, bearing a tube-shaped embolus (em) (Fig. 2A).

Female: Total length 1.14 (Carapace, L: 0.44, W: 0.30. Abdomen, L: 0.70, W; 0.32). In general similar to males: Sternum unmodified in females (Fig. 1E); chelicerae smaller. Genitalia: Epigastric area with copulatory duct not reaching posterior spiracular groove, with thin, narrow semicircular rim which is widen anteriorly and narrow posteriorly (Figs 1G, 2B).

Distribution.

Known only from the type locality (Fig. 21).