Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species
Author
Vermeulen, Jaap J.
Author
Liew, Thor-Seng
Author
Schilthuizen, Menno
text
ZooKeys
2015
531
1
139
http://dx.doi.org/10.3897/zookeys.531.6097
journal article
http://dx.doi.org/10.3897/zookeys.531.6097
1313-2970-531-1
C845838EC9124BD8AB4E07980F91959E
Taxon
classification Animalia Stylommatophora Euconulidae
Rahula delopleura Vermeulen, Liew & Schilthuizen
sp. n.
Figure 75
Rahula
raricostulata
auct.
Schilthuizen and Vermeulen 2003
: 96.
Rahula
sp. V9667 auct.
Clements et al. 2008
: 2762.
Holotype
.
Malaysia
,
Sabah
,
Sandakan Province
,
Kinabatangan valley
,
Batu Pangi
(
RMNH.5003927
).
Examined material from Sabah.
Interior Province. Pinangah valley, Batu Urun (= Bukit Sinobang) (leg. J.J. Vermeulen, V 8006, BOR/MOL 827). Sepulut valley, Gua Pungiton (leg. J.J. Vermeulen & M. Schilthuizen, V 7556; leg. M. Schilthuizen, BOR/MOL 824); Batu Tinagas (leg. M. Schilthuizen, BOR/MOL 826); Gua Sanaron (leg. J.J. Vermeulen & M. Schilthuizen, V 8072). Sandakan Province. Kinabatangan valley, Batu Pangi (leg. J.J. Vermeulen & M. Schilthuizen, V 9667, BOR/MOL 2361); Batu Materis (leg. T.S. Liew & B. Elahan, BOR/MOL 2100); Batu Tomanggong Besar (leg. T.S. Liew & B. Elahan, BOR/MOL 2266, BOR/MOL 2299; leg. M. Schilthuizen, BOR/MOL 2360); Batu Tomanggong Kecil (leg. M. Salverda & H. van Oosten, BOR/MOL 2359). Segama Valley, North end of limestone ridge on East bank Tabin River (leg. J.J. Vermeulen & M. Schilthuizen, V 7787, BOR/MOL 825)). Tawau Province. Batu Baturong, North slope (leg. J.J. Vermeulen, V 7597). Gua Madai c. 40 km S.S.W. of Lahad Datu, N.E. end (leg. J.J. Vermeulen, V 7706). Segama valley, hill N.W. of crossing road Sandakan-Lahad Datu with the Segama River (leg. J.J. Vermeulen & H. Duistermaat, V 1676);
'Kirk's
Cave'
8 km North of Lahad Datu (leg. J.J. Vermeulen, V 1224); limestone hill on North bank Segama River, near bridge of road Sandakan to Lahad Datu (leg. J.J. Vermeulen, V 7512). Semporna area, Segarong Hills, Batu Tengar, 25 km E.S.E. of Kunak (leg. J.J. Vermeulen & H. Duistermaat, V 1820).
Description.
Shell small, rather solid, somewhat translucent to opaque, (pale) brown, conical with convex sides to almost ovoid; apex rounded. Surface shiny. Whorls convex, rounded, suture somewhat imperessed. Protoconch whorls convex, with very fine, densely placed radial riblets starting at some distance from the apex; apex with very fine (just visible at 40 times magnification), inconspicuous spiral striation, which gradually disappears where the radial riblets become more prominent. Teleoconch: Last whorl with a distinct spiral ridge slightly below the periphery, which seems to be the edge of a callus covering the lower surface of the shell, and which continues just above the suture of the penultimate whorl; next to this a fine, dense spiral striation on the lower surface of the shell. Radial sculpture above the spiral ridge consisting of well-spaced (26-33 on the last whorl), coarse, orthocline, approx. straight, high and narrow ribs, which reach down to the spiral ridge and are fused to it, interstices smooth or with an occasional, inconspicuous growth line. Umbilicus closed. Dimensions: Height up to 2.6 mm; width up to 2.1 mm; diameters of the first four whorls 0.5-0.6 mm, 0.8-0.9 mm, 1.1-1.2 mm, 1.35-1.55 mm respectively; number of whorls up to 6 1/2; height aperture up to 0.85 mm; width aperture up to 1.1 mm.
Figure 75.
Rahula delopleura
sp. n. Frontal view, shell 2.7 mm high (Malaysia, Sabah, Sandakan Province, Kinabatangan valley, Batu Pangi, RMNH.5003927, holotype).
Habitat in Sabah and distribution.
Primary and secondary forest on limestone soil, up to 500 m alt. Sabah: Interior (Sepulut valley, upper Pinangah valley); East coast. Endemic to Sabah.
Cross diagnosis.
Differs from
Rahula raricostulata
(E.A. Smith, 1893) (
Sitala raricostulata
E.A. Smith, 1893), from Sarawak, by the absence of a distinct, predominant spiral sculpture on the protoconch.
Rahula raricostulata
has a more conical spire, and fewer radial ribs (11-20) on the last whorl.
All continental Asiatic species of
Rahula
have prosocline radial ribs, see Blanford & Godwin Austen (1908: 249), and
Godwin Austen (1918
: 597).
Etymology.
The name refers to the sculpture [delos (Gr.) = manifest; pleura (Gr.) = rib].