Everettia jucunda, (PFEIFFER, 1863)

Liew, Thor-Seng, Schilthuizen, Menno & Vermeulen, Jaap Jan, 2009, Systematic revision of the genus Everettia Godwin-Austen, 1891 (Mollusca: Gastropoda: Dyakiidae) in Sabah, northern Borneo, Zoological Journal of the Linnean Society 157 (3), pp. 515-550 : 520-522

EVERETTIA JUCUNDA ( PFEIFFER, 1863)

Helix jucunda Pfeiffer, 1863: 524 , figure 263a.

Helix jucunda, Pfeiffer, 1867 –1869: 307.

Nanina (Macrochlamys) jucunda , v. Martens, 1867: 240, plate 12, figure 7.

Nanina jucunda, Issel, 1874: 398 .

Everettia jucunda, Godwin-Austen, 1891: 34–35 , plate 3, fig. 1.

Everettia jucunda, Wiegmann, 1898 : plate 23, figures 23–38.

Macrochlamys (Everettia) jucunda, Kobelt, 1905: 1014 , plate 262, figures 6–7.

Everettia jucunda, Schileyko, 2003: 1360 , figure 1775a.

Type material: BMNH 20040991 , holotype (seen) .

Material examined: SABAH – Tiga Islands : BOR/ MOL 932, vii.2000, BOR/MOL 4237, v.2006, BOR/ MOL 4261, ii.2006 ; JJ 11350 , vii.2003 ; BMNH 1892.7 .20.62.3. Labuan : BMNH 90.7.15.243-5; BMNH 2008216 ; BMNH 2008217 ; BMNH 2008218 . Beaufort : ZMA 176861 , Kuala Penyu , viii.1964. Sipitang : ZMA 176860 , Sipitang beach, vii.1964 ; ZMA 176862 , Sipitang beach, vii.1964. BRUNEI – Brunei : JJ 2493 ; JJ 10038 , Labi Waterfall , iii.2003 .

Diagnostic characteristics: Upper shell dull with more spiral striation and more convex whorls compared with the shiny shell of Everettia jucundior .

Description: Shell ( Figs 2D , 3B ): medium-sized, rather thin, brownish, moderately elevated, outer whorls rounded. Periphery rounded. Above the periphery, shell shiny with a regularly and densely placed spiral striation, c. 30–40 per mm. Below the periphery, shell has fine, densely placed spiral grooves. Height up to 10.5 mm; width up to 17.3 mm; diameter of the first three whorls 0.8–0.9, 0.6–0.7, and 0.8–0.9 mm, respectively; number of whorls up to six and three-quarters; height aperture up to 7.7 mm; width aperture up to 9.8 mm. Genitalia: maximum length from genital opening to the end of dart-sac (before the visible gland tubules) up to c. 13 mm. P, V, GO, BC, and DS arranged around the short genital atrium, with limited space between the opening of each of the genital structures. Long BC almost same length as DS. Animal ( Fig. 4C ): black bands on either side of tentacles, which are divided by a white band occupying the space between eye tentacles, and extended backward to the end of mantle and downward to just below the eye tentacles. Grey smear on either side of the tail extending from the umbilicus region to the end of the tail. Other parts of the animal are devoid of any markings. The mantle is covered by brown irregular markings and followed by regularly spaced radial darker brown bands at the last half whorl.

Distribution and habitat: Primary forest and peat swamp forest. Sabah: Pulau Tiga, Beaufort, Klias Forest Reserve ( Fig. 5A ).

Remarks: The size of the specimens from Brunei is greater than the Beaufort and Pulau Tiga specimens. The type was described from Labuan Island, which is located at the centre of its known distribution range.

Figures

Figure 2. Shells. A, Everettia corrugata corrugata; B, Everettia corrugata williamsi ssp. nov.; C, Everettia interior sp. nov.; D, Everettia jucunda; E, Everettia occidentalis sp. nov.; F, Everettia jucundior sp. nov. Scale bar = 10 mm.

Figure 3. Shell surface sculptures (scanning electron micrograph). A, upper surface of Everettia interior sp. nov.; B, upper surface of Everettia jucunda; C, upper surface of Everettia layanglayang sp. nov.; D, protoconch of E. layanglayang sp. nov.; E, underside of E. layanglayang sp. nov.; F, upper surface of Everettia dominiki sp. nov.; G, upper surface of Everettia monticola sp. nov.; H, upper surface of Everettia planispira sp. nov. Scale bar = 200 Mm.

Figure 4. Animal head and body pigmentation. A, Everettia klemmantanica; B, Everettia interior sp. nov.; C, Everettia jucunda; D, Everettia themis; E, Everettia layanglayang sp. nov.; F, Everettia subconsul; G–I, possible hybrid of E. themis and E. subconsul.

Figure 5. Distribution maps (Sabah). A, Everettia subconsul in the east and west coast lowland, Everettia jucunda in the west coast, and Everettia occidentalis sp. nov. in the western mountain range; B, Everettia klemmantanica in the central mountain ranges, Everettia interior sp. nov. in the interior area, Everettia paulbasintali sp. nov. in the east coast lowland, Everettia themis in the central mountain ranges; C, Everettia lapidini sp. nov. in the central mountain ranges, Everettia jucundior sp. nov. in the east coast lowland; D, Everettia monticola sp. nov. in the central mountain ranges, Everettia planispira sp. nov. in the eastern and northern parts of Sabah.