Haedropleura parva, Scarponi, Daniele, Bella, Giano Della & Ceregato, Alessandro, 2011

Scarponi, Daniele, Bella, Giano Della & Ceregato, Alessandro, 2011, The genus Haedropleura (Neogastropoda, Toxoglossa = Conoidea) in the Plio – Quaternary of the Mediterranean basin, Zootaxa 2796, pp. 37-55 : 46-47

Haedropleura parva n. sp.

Figs. 28–36, 67–69

Type material. Holotype and 14 paratypes (Appendix 1), in Della Bella Collection, MGGC (Bologna, Italy); catalogue numbers 23457 (holotype) and 23458 (paratypes).

Type locality. Poggio alla Staffa (Colle Val d’Elsa, Siena), Italy, (information on the type locality in Bogi et al. 2002; Pedriali & Robba 2005).

Material examined. Pliocene – Zanclean: Villa Filicaia (Florence), 43°32’26”N, 10°55’38”E, 1 sh.; – Piacenzian: La Speranza (Siena), 43°26’29”N, 11°06’01”E, 5 sh.; Poggio alla Staffa (Siena), 43°26’40”N, 11°05’33”E, 9sh.

Description. Shell very small (max length 4.7 mm, max diameter 2.0 mm, see Appendix 1), ovate, solid, whitish or buff-coloured with several paler lines faintly visible on last whorl ( Figs. 22 , 28). Protoconch entirely smooth, paucispiral (of 1.3–1.4 whorls; average diameter 0.58 mm, SD= 0.02 mm; see Appendix 1). Protoconch–teleoconch transition marked well by relatively strong fold or, in most specimens, by narrow sigmoid plica. Teleoconch glossy if well-preserved, of max. ~4.0 whorls, with cyrtoconic spire. Whorls sides almost flat in large specimens, whereas young specimens tend to have moderately convex whorls with periphery below mid-whorl, sutural ramp slightly concave. Suture impressed, undulated. Aperture oblong with evident parietal callus (see Appendix 1). Columellar lip straight, thin. Outer lip thin, backed by wide, round varix, visible only in specimens with more than three teleoconch whorls; varix spreading forwards, corresponding to shallow but broad subsutural sinus, then curving rapidly downwards, extending almost straight to ill-defined anterior siphonal canal; canal wide, without notch. Last whorl about 2/3 of shell length. Axial sculpture consists of 7–9 prominent, straight axial ribs and well-marked grow lines (see Appendix 1). Axial ribs on spire whorls pinched adapically, extending from suture to suture; less numerous on last whorl in most specimens (mode=8, Appendix 1), fading rapidly towards neck. Spiral sculpture consists of dense, faint, close-set threads, with very shallow incised interspaces, evident only in well-preserved specimens. Etymology. This species is named for its small dimensions.

Distribution. Haedropleura parva n. sp. is known from several Pliocene outcrops in Tuscany (see above).

Remarks. Haedropleura parva has all the principal characters of the genus Haedropleura . Its very small dimensions coupled with adult features (that is, parietal callus and variced outer lip) make the species distinctive. The new species has a certain teleoconch affinity with H. septangularis . However, it is easily differentiated from H. septangularis by its smaller teleoconch (average height 4.1 mm, SD= 0.6 mm vs. 9.3 mm, SD= 2.4 mm respectively) and by its different protoconch development (paucispiral vs. multispiral). The combination of adult features and small size make H. parva easily distinguishable also from all congeneric species (see Appendix 1).

Figures

FIGURES 19 – 27. Haedropleura formosa n. sp. 19 – 21, # 54, Maiola (Bologna), Gelasian (Pleistocene); 22 – 24, # 46 holotype, 25 – 27, # 51 paratype, Codrignano (Bologna), Calabrian (Pleistocene). FIGURES 28 – 36. H. parva n. sp. 28 – 30, # 72, La Speranza (Siena), Piacenzian (Pliocene); 31 – 33, # 63 paratype, 34 – 36, # 62 holotype, Poggio alla Staffa (Siena), Zanclean (Pliocene). Scale bars 1 mm; # = shell number in Appendix 1.