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

Sulawesidrobia ehrlichi sp. nov.

urn:lsid:zoobank.org:act: 329722EB-1CD2-4441-AFC1-4C69C9203758

Figs 2C, 3E–F, 4C–D, 6E, 7E–F, 8E–F

This new species is a larger conical Sulawesidrobia with a characteristic radula in which the denticles of the central tooth are fused, the central denticles of both central and lateral teeth have rounded tips, and the denticles on the lateral teeth are comparatively large and reduced in number. It is the only larger conical species with a broad based penis and slender, parallel-sided distal end. There are three diagnostic positions, two of type 1 and one of type 3 (Table 3).

Named in honor for the American biologist Paul Ralph Ehrlich (born 1932), best known for his early warnings of the devastating effects of overpopulation depleting natural resources in his 1968 book The Population Bomb, coauthored with his wife Anne.

Holotype (Fig. 2C)

INDONESIA • 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. 12120.

Paratypes (Fig. 3E–F)

INDONESIA • 70 specs; same collection data as for holotype; MZB Gst. 12121 • 69 specs; same collection data as for holotype; ZMB 107095.

SHELL (Figs 2C, 3E–F, 4C–D). Short-conical, sutures very shallow, about 1.6 times as high as wide, shell and periostracum light brown; protoconch with fine pits and ca 0.8 whorls; entire shell with 4.125 to 4.750 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 with the exception of mantle rim and areas over distal genital glands and stomach; tentacles with ciliated field.

MANTLE CAVITY (N = 4). 17–20 ctenidial filaments; osphradium elongate lying under posterior two thirds of ctenidium.

DIGESTIVE SYSTEM. The radula has the formula R 4-5 1 4-5/3 3, L 2 1 2-4, M1 10-12, M2 18-24, denticles of central tooth basally fused, central denticles of both central and lateral teeth with rounded tip, denticles of lateral tooth comparatively large but reduced in number, innermost cusp of lateral tooth may be very small (Fig. 6E); stomach black without caecum; intestine follows pallial genital glands, in females closer than in males.

FEMALE GENITALIA (N = 2; Fig. 7E–F). Ovary starts 1–1.25 whorls below apex, comprises 0.5 whorls and covers the stomach chambers; renal oviduct first coiling 180° clockwise, then 270° counter-clockwise; no receptaculum seminis; bursa copulatrix egg-shaped behind albumen gland, bursal duct entering anteriorly; albumen gland milky-white, capsule gland with smaller anterior white and larger posterior yellow portion.

MALE GENITALIA (N = 2). Testis lobate, starts 0.75–1 whorls below apex, comprises ca 1.25 whorls, covers stomach chambers; vesicula seminalis coils along anterior half of testis; vasa deferentia insert close to middle of kidney-shaped prostate; penis with slightly broadened base and long, slender, parallel-sided distal end (Fig. 8E–F).

The unresolved relationships with S. crutzeni sp. nov., possibly due to incomplete lineage sorting, suggest a close relationship (Figs 9–10, Supp. file 1) reflected also by the low number of diagnostic alignment positions, two of which were of type 1 and one of type 3 (Table 3). Yet, radular and genital features clearly indicate that both are distinct. Lateral and both marginal teeth have considerably less denticles in S. wilsoni sp nov. than in S. crutzeni. The latter lacks a bursa copulatrix and its penis is broad-based with a long, tapering distal end (see below). Sulawesidrobia dinersteini sp. nov. shares the lateral tooth morphology seen in this species (see below).