Opisthostoma javanicum Van Benthem Jutting 1932
Creators: name: Hausdorf, Bernhard
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Architaenioglossa
Diplommatinidae
Opisthostoma
Opisthostoma javanicum

description: Opisthostoma javanicum van Benthem Jutting, 1932
(Figs 19, 49–51; Table 3)
Opisthostoma javanica Van Benthem Jutting, 1932: 203, pl.VII, fig. 8 a, b, c, d (Goenoeng TjibodaS (EState of Tjampea) near Buitenzorg, JaVa, 300 m alt.).
Opisthostoma javanicum — Van Benthem Jutting 1948: 587, fig. 45. Vermeulen 1991: 160, fig. 10a. Whitten et al. 1997: 294. Vermeulen & Whitten 1998: 51, 138, fig. 30. MaaSSen 2003: 60, fig. 23–24.
Opisthostoma (Opisthostoma) aspastum Van Benthem Jutting, 1951: 30, fig. 1 (LimeStone hillS of Pangkadjene, near MakaSSar, South CelebeS, Sea leVel).
Opisthostoma aetheroscopa Vermeulen, 1991: 155, fig. 8a, b (Gomantong Hill 30 km S. of Sandakan).
Opisthostoma (Opisthostoma) javanicum —Vermeulen 1994: 101, fig. 68.
Opisthostoma uranoscopium — Whitten et al. 1997: 294 (not Van Benthem Jutting, 1932).
Diagnosis. Opisthostoma javanicum is characterized by the aperture pointing backwards.
Shell (Figs 49–51; Table 3). Dextral; first 2.5 whorls conical; the next whorls narrower than the preceding one and then there is a distinct constriction and the coiling changes; the last part of the fourth whorl ascends attached to the preceding whorl towards the aperture, which is turned backwards and forms a plane, almost vertical or tilted up to 45 degrees with regard to the main axis of the shell; with 4–4.5 whorls separated by a deep suture; protoconch smooth; teleoconch with oblique ribs (7–12 per mm or 19–35 ribs on penultimate whorl), in some individuals with doubled edges; with indistinct spiral striae between the ribs; whitish; subtranslucent; last whorl rounded; aperture almost circular; upper margin of aperture is below the level of the apex; insertions of the peristome connected by a thick callus; peristome expanded, thickened, doubled; aperture without teeth; without parietal and columellar lamellae inside the last whorl; with an oblique palatal fold inside the last whorl at the constriction; umbilicus narrow. Shell height 0.9–1.1 mm, shell width 0.7–0.95 mm (without aperture) or 1.25–1.45 mm (with aperture).
Remarks. The populations of the O. javanicum complex from western and eastern Java are different. The typical form from West Java is characterized by very small shells (shell height 0.95–1.05 mm, mean 0.98 mm; shell width 1.25–1.4 mm, mean 1.30 mm [with aperture]) with close-set, mainly double-crested ribs (10–12 per mm or 26–35 ribs on penultimate whorl) and an almost vertical aperture (Fig. 49). The forms from Yogyakarta (Fig. 50) and Alas Purwo National Park in Eastern Java (Fig. 51) have more widely spaced, single-crested ribs (7–8 per mm or 19–24 ribs on penultimate whorl) and are on average larger (shell height 0.95–1.1 mm, mean 1.00 mm; shell width 1.3–1.45 mm, mean 1.36 mm). In the specimens from Alas Purwo National Park the aperture is tilted about 45 degrees relative to the main axis of the shell, whereas the aperture of specimens from Yogyakarta is less tilted.
If these differences between populations from western and eastern Java prove to be constant, they might be separated as subspecies or even as species, depending on the occurrence of intermediate forms. The situation is complicated by the occurrence of forms of the O. javanicum complex on Borneo and Sulawesi and their variability. The specimens from Borneo figured by Vermeulen (1991: fig. 10a) and Vermeulen & Whitten (1998: fig. 30) and from Sulawesi by Maassen (2003: 60, fig. 23–24) correspond better to the forms from eastern Java. Thus, the name O. javanicum aspastum van Benthem Jutting, 1951 might be used for this group, if it is homogeneous. However, it is possible that the populations from Borneo and Sulawesi are separate from those of Java. Vermeulen (1991) mentioned a columellar lamella in O. javanicum from Borneo (and also in O. aetheroscopa Vermeulen, 1991, which has been synonymized with O. javanicum by Vermeulen 1994). We have not found a columellar lamella in two opened specimens from West and East Java.
Habitat. In leaf litter, on the vegetation and on limestone rocks in primary and secondary forests on calcareous and volcanic soils at 0–500 m a.s.l.
Type material. Indonesia, Java, West Java: Bogor, Ciampea, Mt. Cibodas, 6°33'S 106°41'E (syntypes of O. javanicum ZMA 136008 /5).
Other material. Indonesia, Java, West Java: Sukabumi, Cibitung, Cikaso waterfall, 58 m a.s.l., 7°21'37"S 106°37'05"E (MZB 18877/1); Bogor, Ciampea, Mt. Cibodas, 296 m a.s.l., 6°33'05''S 106°41'09''E (MZB 18876/1); Pangandaran, 7°41'S 108°40'E (JV 4107/8, voucher to Whitten et al. 1997).—Yogyakarta: Gunungkidul, Payen, near Srigetuk waterfall, 101 m a.s.l., 7°56'35"S 110°29'21"E (MZB 18892/1; ZMH 133058/1).—East Java: Madura Island, 14 m a.s.l., 6°55'S 113°54'E (MZB 9456/3, voucher to Vermeulen 1991); South of Ketapang, 6°54'S 113°17'E (JV 2999/12, voucher to Whitten et al. 1997); Banyuwangi, Alas Purwo National Park, on the way to Padepokan cave, 93 m a.s.l., 8°40'03"S 114°23'07"E (MZB 18890/2; ZMH 133056/1); Banyuwangi, Alas Purwo National Park, Istana cave towards Mayangkoro cave, 10 m a.s.l., 8°40'11"S 114°23'08"E (MZB 18891/2; ZMH 133057/4).
Distribution (Fig. 19). Opisthostoma javanicum has been recorded beside from Java and Madura also from Bali, Borneo and Sulawesi (van Benthem Jutting 1951; Vermeulen 1991; Vermeulen & Whitten 1998; Maassen, 2003).
description: Published as part of Hausdorf, Bernhard, 2017, Revision of the Diplommatinidae (Gastropoda: Cyclophoroidea) from Java, pp. 201-245 in Zootaxa 4312 (2) on pages 239-240, DOI: 10.11646/zootaxa.4312.2.1, http://zenodo.org/record/892895