Sulawesidrobia crutzeni sp. nov.

urn:lsid:zoobank.org:act: D1E8AE3D-C211-4CAC-B4E8-16623EEA9853

Figs 2D, 3G–H, 5C, 6F, 7G–H, 8G

Diagnosis

This new species is a large conical Sulawesidrobia and the only one in which no bursa copulatrix was seen. The single inner denticle of the lateral tooth is very large. The four diagnostic alignment positions are all only of type 3 (Table 3).

Etymology

Sulawesidrobia crutzeni sp. nov. is named after the Dutch meteorologist, atmospheric chemist and 1995 Nobel Prize winner Paul J. Crutzen (1933–2021) who not only studied the effect of mankind on climate change but also coined (together with the freshwater biologist Eugene F. Stoermer) and popularized the term and concept of the Anthropocene, a proposed new epoch in the Quaternary period.

Material examined

Holotype (Fig. 2D)

INDONESIA • Sulawesi, Lake Matano, N shore, SE of Nuha, on rocks; 02°27.721′ S, 121°23.125′ E; 24 Oct. 2005; Glaubrecht leg.; MZB Gst. 12122.

Paratypes (Fig. 3G–H)

INDONESIA • 15 specs; same collection data as for holotype; MZB Gst. 12123 • 13 specs; same collection data as for holotype; ZMB 191838 .

Description

SHELL (Figs 2D, 3G–H). Conical with convex outline, appearance fairly massive, sutures shallow, about 1.5 times as high as wide, periostracum and translucent shell brown with white subsutural band; protoconch structure not verified due to corosion, comprises ca 0.8 whorls; entire shell with 3.875 to 4.375 whorls, teleoconch without structure apart from growth lines; umbilicus a narrow slit; aperture slightly higher than wide, outer lip orthocline.

OPERCULUM. Very 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 small ciliated field (Fig. 5C).

MANTLE CAVITY (N = 3). 20–23 ctenidial filaments; osphradium elongate underneath central two thirds of gill.

DIGESTIVE SYSTEM. The radula has the formula R 3-4 1 3-4/3 3, L 1 1 4-5, M1 14-18, M2 23-26, inner denticle of lateral tooth very large (Fig. 6F); stomach without caecum and pigment; intestine follows pallial genital glands, in females closer than in males.

FEMALE GENITALIA (N = 2; Fig. 7G–H). Ovary starts ca 1.25 whorls below apex, comprises 0.5–0.7 whorls, covers stomach chambers; renal oviduct first coiling 180° clockwise, distal part more variable, in one individual coiling then 270° counter-clockwise and again 180° clockwise (Fig. 7G), in the second female dissected 180° counter-clockwise and then 270° counter-clockwise (Fig. 7H); no receptaculum seminis; no bursa copulatrix seen; albumen gland anteriorly opaque-white merging gradually into a milky-white posterior portion, capsule gland with a smaller anterior white and a larger posterior yellow portion.

MALE GENITALIA (N = 1; Fig. 8G). Lobate testis starts ca 1 whorl below apex, comprises ca 1 whorl, covers stomach; vesicula seminalis coils along anterior half of testis; vasa deferentia insert close to middle of relatively small, almost rectangular prostate; penis with massive, broad base and long, slender and tapering distal end, distally grey.

Remarks

This is the only species of Sulawesidrobia apparently lacking a bursa copulatrix. It would be desirable, though, to check this characteristic in well-fixed material as here the preservation was far from ideal and only few specimens were available. Mosaic similarities with all three above described species are discussed under their respective Remarks.As S. crutzeni sp. nov. was paraphyletic (see below, Figs 9–10, Supp. file 1), it was not surprising that the four diagnostic alignment positions were all only of type 3 (Table 3).