Contributions to Zoology, 86 (1) – 2017Isabel T Hyman; Irantzu de la Iglesia Lamborena; Frank Köhler: Molecular phylogenetics and systematic revision of the south-eastern Australian Helicarionidae (Gastropoda, Stylommatophora)
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Brevisentis atratus Hyman, 2007

Figs 7C, 12

Brevisentis atratus Hyman, 2007: 94-95, fig. 2; Stanisic et al., 2010: 280-282, 324.

 

Material examined. Holotype. AM C.446473 (Coolah Tops NP, at lookout 1km S of Pinnacle Lookout, end of Pinnacle Rd, NSW, 31°41.8’ S, 150°1.1’ E, basalt rock pile at edge of escarpment, leg. Shea, 26/5/2000).

Paratypes. AM C.44645 (same data as holotype).

Non-type material. See Table S1. Additional material: AM C.446477, AM C.360695, AM C.164160, AM C.135218, AM C.446459, AM C.517469.

 

Diagnosis. Shell. Medium size, 4.65-5.5 whorls, pale amber, depressedly globose to discoidal; whorls rounded; protoconch with very fine spiral grooves; teleoconch with spiral rows of tiny pustules; umbilicus narrow (Table 3, Fig. 7C).

Animal. Body dark grey to black with red mucus; tiny specks of red pigment visible in living animal; sole pale grey with a paler mid field; caudal horn small. Mantle lobes moderately small, not fused; shell lappets narrow, triangular, right lappet moderately long, left lappet moderately short.

Genitalia. Penis relatively long, sometimes not fully enclosed in penial tunica, not swollen proximally. Penis interior with primarily longitudinal pilasters at distal end, breaking into wavy pilasters then into pustules at proximal end; interior with a sharp narrowing near proximal end that is not visible externally, effectively dividing penis into two separate chambers. Epiphallus relatively short, approximately 1.5 times penis length, entering penis to one side through short verge (about ¼ penis length), leaving a small blind penis tip. Epiphallic flagellum with small internal cryptae near epiphallus, tail of flagellum without visible cryptae. Spermatophore not observed (Fig. 12).

FIG2

Fig. 12. Reproductive anatomy of Brevisentis atratus, AM C.360695. A. Genitalia. B. Spermatophore. B. Penial interior. Abbreviations: alb, albumen gland; bc, bursa copulatrix; cg, capsule gland; ep, epiphallus; fl, flagellum; her, hermaphroditic duct; ov, ovotestis; p, penis; pp, penial pilasters; pr, prostate; prm, penial retractor muscle; pt, penial tunica; pv, penial verge; ut, uterus; vd, vas deferens. Scale bars: A = 2 mm, B = 1 mm.

Remarks. When first described, B. atratus was recorded from Mt Gibraltar (Bowral, SE NSW) to Coolah Tops National Park in the Hunter region (Hyman, 2007). Specimens from the Blue Mountains, Bathurst and Warrumbungle National Park, mistakenly attributed to B. jacksoniensis, are here shown to belong to B. atratus (Fig. 11). This species is found in rocky outcrops in vine thicket, sclerophyll forest and open woodland, living under rocks, logs and litter.

Brevisentis atratus can be distinguished from B. jacksoniensis by its black body colouration and lower-spired shell, and from B. kaputarensis by its larger and paler shell with a flatter spire. It has a very distinctive penial anatomy, with a longer penis than its congeners, distinguished by a narrowing near the proximal end that gives the impression of two separate chambers and a small blind tip.