Sulawesidrobia dinersteini Haase & Rintelen & Harting & Marwoto & Glaubrecht 2023, sp. nov.

Sulawesidrobia dinersteini sp. nov.

urn:lsid:zoobank.org:act: 5AD928D7-232F-4D7E-AB84-FE9BA9D471F4

Figs 2E, 3I–J, 5D, 6G–H, 7I–J, 8H (all from type locality)

In the new species, the penis tapering continuously from a broadened base with triangular lobe in about the middle on the right side is unique within the genus. Six diagnostic positions are of type 1 and three of type 3 (Table 3).

Sulawesidrobia dinersteini sp. nov. is named after the American conservation biologist Eric Dinerstein (born 1952) for his influential contributions in identifying representative and biologically important ecoregions which help to develop a global safety net aiming to at least protect 30 percent of Earth’s surface in order to save a considerable fraction of biodiversity.

Holotype (Fig. 2E)

INDONESIA • Sulawesi, Lake Matano, S shore, on rocks and macrophytes; 02°27.850′ S, 121°13.870′ E; 1 Aug. 2004; von Rintelen and Zitzler leg.; MZB Gst. 12124.

Paratypes (Fig. 3I–J)

INDONESIA • 40 specs; same collection data as for holotype; MZB Gst 12125 • 38 specs; same collection data as for holotype; ZMB 107092 • 11 specs; Sulawesi, Lake Matano, S shore, on rocks and macrophytes; 02°28.461′ S, 121°15.591′ E; 24 Jul. 2004; von Rintelen and Zitzler leg.; MZB Gst 12126 • 11 specs; same collection data as for preceding; ZMB 107094.

SHELL (Figs 2E, 3I–J). Short-conical, sutures very shallow, about 1.6 times as high as wide, shell and priostracum light brown; protoconch structure not verified, ca 0.8 whorls; entire shell with 3.500 to 4.250 whorls, teleoconch without structure apart from growth lines; umbilicus a narrow slit; aperture orthocline, only slightly higher than wide.

OPERCULUM. Light yellow and thin, paucispiral, nucleus eccentric.

EXTERNAL FEATURES. Epidermis entirely black except mantle edge, eventually pigment less dense over distal genital glands; tentacles with small, central field of cilia (Fig. 5D).

MANTLE CAVITY (N = 4 from each locality). 16–18 (type locality) and 14–17 (2 nd locality) ctenidial filaments, respectively; osphradium ovate-elongate, underneath middle or slightly behind middle of gill, half to two thirds of length of gill.

DIGESTIVE SYSTEM. The radula has the formula R 3-4 1 3-4/3-4 3-4, L 2 1 2-3, M1 15-20, M2 23-28, central denticle of lateral tooth with rounded tip (Fig. 6G–H); stomach without caecum, without pigment at type locality, pigmented at locality 2; intestine follows pallial genital glands, in females closer than in males.

FEMALE GENITALIA (N = 2 from each locality; Fig. 14I–J). Ovary starts ca 1.25 or slightly more whorls below apex, comprises ca 0.5 whorls, covers stomach chambers; renal oviduct first coiling 180° clockwise, then 270° counter-clockwise; no receptaculum seminis; bursa copulatrix more or less globular, bursal duct enters anteriorly; albumen gland with opaque-white anterior and milky-white posterior section, capsule gland with small opaque white and large yellow posterior portion.

MALE GENITALIA (N = 2 from each locality; Fig. 8H). Testis lobate, starts 0.75 (type locality) to 1 whorl (locality 2) below apex, comprises ca 1.25 whorls, covers stomach; vesicula seminalis coils along distal half to 0.75 whorls of testis; vasa deferentia insert close to middle of kidney-shaped prostate, which is much longer (almost twice as long) in locality 2 than at type locality; penis tapering continuously from broadened base, with triangular lobe in about middle on right side, can be considerable longer than in Fig. 8H, distal end subterminally grey.

In the phylogenetic trees, S. dinersteini sp. nov. received high support. Its penis is unique as it is considerably shorter than the similar one of S. megalodon (see Zielske et al. 2011). Some similarity of the radula with that of S. ehrlichi sp. nov. has already been mentioned above. Sulawesidrobia dinersteini had the highest number of diagnostic alignment positions (Table 3) among the new species which clearly reflects the well-supported position in the phylogenetic analyses (see below, Figs 9–10, Supp, file 1).