Sulawesidrobia wilsoni, Haase & Rintelen & Harting & Marwoto & Glaubrecht, 2023

Haase, Martin, Rintelen, Thomas von, Harting, Britta, Marwoto, Ristiyanti & Glaubrecht, Matthias, 2023, New species from a ‘ lost world’: Sulawesidrobia (Caenogastropoda, Tateidae) from ancient Lake Matano, Sulawesi, Indonesia, European Journal of Taxonomy 864 (1), pp. 77-103 : 82-84

Sulawesidrobia wilsoni sp. nov.

urn:lsid:zoobank.org:act:06EBD388-C63B-4C22-BB74-4FC6970B6CAE

Figs 2A , 3A–B , 5A , 6A–C , 7A–B , 8A–B

Diagnosis

Sulawesidrobia wilsoni sp. nov. is characterized by the combination of the unique egg-shaped shell with very weakly depressed sutures, a white subsutural band and an enlarged denticle close to the base of the inner marginal radular tooth. Only two alignment positions are diagnostic, one of type 1 and one of type 3 ( Table 3 ).

Etymology

Sulawesidrobia wilsoni sp. nov. is named after the American naturalist Edward Osborn Wilson (1929– 2021), who not only contributed significantly to the ecological theory of biogeography as an important aspect of conservation biology, but coined biodiversity as an important agenda for our and the next generation.

Material examined

Holotype ( Fig. 2A )

INDONESIA • Sulawesi, Lake Matano , N-shore, NW of Nuha , on rocks; 02°26.261′ S, 121°18.692′ E; 24 Oct. 2005; Glaubrecht leg.; MZB Gst. 12116 .

Paratypes ( Fig. 3A–B )

INDONESIA • 27 specs; same collection data as for holotype; MZB Gst. 12117 • 27 specs; same collection data as for holotype; ZMB 191842 .

Description

SHELL ( Figs 2A , 3A–B ). Egg-shaped, height of whorls increasing allometrically, sutures hardly incised, height of body whorl about four fifths of total height, total shell about 1.5 times as high as wide, browntranslucent with white subsutural band, periostracum light brown; protoconch comprising ca 0.9 whorls; entire shell with 3.5 to 3.875 whorls without structure apart from growth lines; umbilicus at best a narrow slit; aperture orthocline, only slightly higher than wide, outer lip hardly extends beyond body whorl.

OPERCULUM. Very pale yellow, thin, paucispiral, nucleus eccentric.

EXTERNAL FEATURES. Epidermis black except for mantle edge and areas over distal genital glands and stomach; tentacles black with median white stripe and patch of cilia ( Fig. 5A ).

MANTLE CAVITY (N = 3). 16–19 ctenidial filaments; osphradium ovate-elongate lying centrally under ctenidium along 75% of its length.

DIGESTIVE SYSTEM. The radula has the formula R 4-5 1 4-5/2-3 2-3, L 3 1 6-7, M1 24-25, M2 23-26, two rhachidial basal cusps were only rarely observed, the first marginal tooth has proximally an enlarged denticle ( Fig. 6A–C ); stomach without caecum and pigment; intestine follows distal genital glands, in females closer than in males.

FEMALE GENITALIA (N = 2; Fig. 7A–B ). Ovary starts 1–1.5 whorls below apex, comprises about 0.5 whorls and overlaps proximal stomach chamber; renal oviduct simple, first coiling 180° clockwise, then 270° counter-clockwise; no receptaculum seminis; bursa copulatrix broadly pear-shaped, behind albumen gland, bursal duct entering subcentrally; albumen gland with opaque-white anterior and milky-white posterior section, anterior capsule gland white, posterior one yellowish.

MALE GENITALIA (N = 2; Fig. 8A–B ). Testis lobate, starts about one whorl below apex, comprises ca 1.25 whorls, extends over stomach; vesicula seminalis coils along anterior two thirds of testis; proximal and distal vasa deferentia insert closely in about middle of kidney-shaped prostate; penis with broad base and slender, parallel-sided elongate distal end.

Remarks

The white subsutural band is shared with S. crutzeni sp. nov. described below. An enlarged denticle close to the base of the inner marginal radular tooth is seen in two other species, S. megalodon Zielske, Glaubrecht & Haase, 2011 ( Zielske et al. 2011) and S. bulat Haase & Bouchet, 2006 ( Haase & Bouchet 2006). All three are morphologically very different from S. wilsoni sp. nov., though. Sulawesidrobia crutzeni is much larger and has a conical shell (see below) while S. megalodon is trochiform ( Zielske et al. 2011), and S. bulat globular ( Haase & Bouchet 2006). In addition, S. crutzeni lacks a bursa copulatrix. In the phylogenetic trees ( Figs 9–10 , Supp. file 1), S. wilsoni received high support although there were only two diagnostic alignment positions, one of type 1 and one of type 3 ( Table 3 ).

Figures

Fig. 2. Holotypes. A. Sulawesidrobia wilsoni sp. nov. (MZB Gst. 12116). B. S. carsonae sp. nov. (MZB Gst. 12118). C. S. ehrlichi sp. nov. (MZB Gst. 12120). D. S. crutzeni sp. nov. (MZB Gst. 12122). E. S. dinersteini sp. nov. (MZB Gst. 12124). Scale bar = 1 mm.

Fig. 3. SEM micrographs of paratypes, all from type localities. A–B. Sulawesidrobia wilsoni sp. nov. (MZB Gst. 12117). C–D. S. carsonae sp. nov. (MZB Gst. 12119). E–F. S. ehrlichi sp. nov. (MZB Gst. 12121). G–H. S. crutzeni sp. nov. (MZB Gst. 12123). I–J. S. dinersteini sp. nov. (MZB Gst. 12125).

Fig. 5. SEM micrographs of cephalic tentacles. A. Sulawesidrobia wilsoni sp. nov. (ZMB 191842). B. S. carsonae sp. nov. (ZMB 107079). C. S. crutzeni sp. nov. (ZMB 191838). D. S. dinersteini sp. nov. (ZMB 107092). Arrows indicate field of cilia. Scale bars: A–B, D = 20 µm; C = 50 µm.

Fig. 6. Radula. A–C. Sulawesidrobia wilsoni sp. nov. D. S. carsonae sp. nov. E. S. ehrlichi sp. nov. F. S. crutzeni sp. nov. G–H. S. dinersteini sp. nov. Note different shapes of denticles on central and lateral teeth across species. Arrows indicate enlarged denticle on marginal tooth 1 in S. wilsoni sp. nov. Scale bars: A, C–G = 10 µm; B, H = 5 µm.

Fig. 7. Distal female genitalia. A–B. Sulawesidrobia wilsoni sp. nov. C–D. S. carsonae sp. nov. E–F. S. ehrlichi sp. nov. G–H. S. crutzeni sp. nov. I–J. S. dinersteini sp. nov. Abbreviations: aa = anterior albumen gland; ac = anterior capsule gland; bc = bursa copulatrix; bd = bursal duct; od = oviduct; pa = posterior albumen gland; pc = posterior capsule gland; vc = ventral channel.

Fig. 8. Penis. A–B. Sulawesidrobia wilsoni sp. nov. (ZMB 191842). C–D. S. carsonae sp. nov. (ZMB 107079).E–F. S. ehrlichi sp. nov. (ZMB 107095).G. S. crutzeni sp. nov. (ZMB 191838).H. S. dinersteini sp. nov. (ZMB 107092). Arrow indicates lobe in H. Scale bars: A–F, H = 50 µm; G = 100 µm.

Fig. 9. Bayesian phylogenetic analysis. Outgroup pruned from tree. Taxa represented by “species name_ZMB catalogue number and specimen_abbreviation of lake”. Numbers at nodes are posterior probabilities> 0.50. Scale in substitutions per site.

Fig. 10. Maximum likelihood phylogenetic analysis. Outgroup pruned from tree. Taxa represented by “species name_ZMB catalogue number and specimen_abbreviation of lake”. Numbers at nodes are bootstrap support values> 50. Scale in substitutions per site.