Haedropleura septangularis ( Montagu, 1803 )

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 : 40-42

Haedropleura septangularis ( Montagu, 1803)

Figs. 1–6 , 49–54

Murex septangularis Montagu, 1803: 268 , pl. 9, fig. 5.

Pleurotoma heptagona Scacchi, 1835: 42 , pl. 1, fig. 17.

Bela septangularis Bellardi, 1877: 147 (with synonymy).

Bela (Haedropleura) septangularis Sacco, 1904: 47 , pl. 12, figs. 51–52.

Bela (Haedropleura) septangularis Cerulli-Irellli, 1910: 51 [243], pl. 4 [35], figs. 55–57 (with synonymy). Bellaspira septangularis Nordsieck, 1977: 13 (in part), pl. 1, fig. 6.

? Bellaspira septangularis maderensis Nordsieck, 1977: 13 , pl. 1, fig. 7.

Haedropleura septangularis Chirli, 1997: 37 , pl. 10, figs. 5–7 (with synonymy). non Haedropleura septangularis Ardovini & Cossignani, 1999: 67 , fig. 125 (= H. secalina ).? Haedropleura septangularis Delamotte & Vardala-Theodorou, 2001: 136 , fig. A. Haedropleura septangularis Scarponi & Della Bella, 2004: 55 , figs. 85–87, 92 (with synonymy).

Original description. [M. with seven or eight, strong, smooth, tapered whorls, terminating in a fine point, of a light purplish-brown colour and somewhat glossy; with seven longitudinal ridges, that run the whole length, scarcely interrupted by the separating line: the sides, or space between the ribs, are but little concave, which gives the shell a heptagonal appearance: aperture oblong-oval, ending in a short canal; outer lip sharp at the edge, thickened at the back by a ridge, the upper part contracted to an angle, where the margin is a little indented; pillar lip a little replicated. Length five-eighths of an inch; breadth two eighths; but rarely so large. Sometimes this shell is white at the junction of each whorl; worn specimens are dull, opaque white (...)].

Type material. Lectotype ( RAMM) Montagu Collection, catalogue number EXEMS:63/1976/4251 (Dave Bolton, RAMM curator pers. comm.). Montagu (1803) stated that his specimens were from Falmouth, Salcombe and Weymouth (South West, Great Britain), so apparently he had at least three (but probably more, as it is possible to deduce from the original description). The original collection is represented now by only a single shell ( Bernasconi & Robba 1984), from Britain (as indicated in the original Montagu’s label), with no more detail of its collection locality (Dave Bolton pers. comm.). This remaining syntype was reported as the holotype by Bernasconi & Robba (1984). However we were not able to find in that paper any statement with which the two authors explicitly indicated that they were selecting that particular specimen to serve as the name-bearing type. Following ICZN Code, 1999, art. 74.5, a subsequent use of the term “ holotype ” does not constitute a valid lectotype designation. Hence, the RAMM specimen is here designated the lectotype in accordance with the purpose of ensuring the name’s proper and consistent application of a taxon (see ICZN Code, 1999: article 74.7.3).

Type locality. “ Britain ” ( Great Britain).

Material examined. Pliocene – Zanclean: Villa Filicaia (Florence), 43°32’26”N, 10°55’38”E, 4 sh.; – Zanclean/Piacenzian: Poggio alla Staffa (Siena), 43°26’40”N, 11°05’33”E, 1 sh.; – Piacenzian: Melograni (Siena), 43°26’23”N, 11°03’05”E, 8 sh.; Terre Rosse (Siena), 43°19’32”N, 11°30’50”E, 2 sh. Recent: Capo Comino ( Italy), 40°33’00”N, 9°49’31”E, - 25m, 4 sh.; Calafuria ( Italy), 43°28’18”N, 10°19’52”E, - 20m, 1 sh.; Devon ( Great Britain) and Mediterranean MGGC collection, depth not stated, 2 sh.; Punta Ala ( Italy), 42°48’23”N, 10°44’48”E, - 3m, 2 spm; Quercianella ( Italy), 43°26’36”N, 10°19’34”E, - 41m, 3 sh.; San Vincenzo ( Italy), 43°05’39”N, 10°30’35”E, -15/ 18m, 1 sh.; Torre San Giovanni ( Italy), 39°53’18”N, 18°06’33”E, - 3m, 1 sh.

Distribution. Haedropleura septangularis is known from the entire Mediterranean Sea, north to the Atlantic coasts of Europe, on gravelly bottoms from 10 m to 50 m depth ( Monterosato 1884; Fretter & Graham 1978). The fossil material has been reported from: Miocene (Helvetian) of the Loire Basin, France ( Glibert 1954 however, this material needs further investigation), Pliocene of Great Britain ( Harmer 1915), and Plio–Pleistocene of the Mediterranean Basin (see synonymy).

Remarks. Haedropleura septangularis has a solid, fusiform, glossy shell, with a multispiral protoconch (2.2 to 2.6 whorls; average diameter 0.65 mm, SD= 0.04 mm; see Appendix 1), indicating planktotrophic larval development. Pliocene specimens tend to have a slightly higher number of protoconch whorls and smaller diameter of the first embryonic whorl than living specimens (that is, number of whorls 2.40–2.60 vs. 2.20–2.40, see Appendix 1 and Figs. 49–50, 52–53 ). However, this distinction is not statistically significant at the examined sample size. Protoconch sculpture is mainly smooth except for sparse punctate markings, restricted to the suture area, along with a few opisthocline, arched plicae. The latter are present only on the last whorl.

Teleoconch consists of max. 6.5 whorls, slightly convex on their abapical half and almost straight and oblique on their adapical part, giving the spire a distinctive conical outline. The most conspicuous axial ornament is prominent, slightly arched, opisthocline costae that entirely cross the whorl deflecting the suture (7 to 8 on the last whorl; see also Appendix 1). Growth lines are usually evident and follow the outer lip shape. The teleoconch spiral ornamentation consists of small, flat ridges, mainly even in size except for the fasciole and neck, where they are smaller and coarser than higher up. The aperture is elongate-oval, with a well-developed parietal callus on most specimens. The callus modifies the anal sinus outline in some specimens ( Fig. 2 ). The outer lip is thin but is backed by a strong varix in most specimens. The lip curves forward, forming a shallow but broad sinus, then curves rapidly down and extends almost straight to a short anterior canal ( Figs. 1–4 ). The columellar lip is straight and thin, with no umbilical groove. For anatomical features we refer to Fretter & Graham (1978; and references therein).

The teleoconch outline and sculpture show strong affinities to those of Haedropleura secalina (see below, and Appendix 1). However, the protoconch provides helpful diagnostic characters to discriminate easily between the two species. The paucispiral apex of H. secalina , with a wide, papillose embryonic whorl, is completely different from the H. septangularis multispiral protoconch with a smaller, blunt embryonic tip. Besides, H. septangularis has several relatively strong arcuate plicae at the teleoconch junction that are missing in H. secalina . Protoconch dimensions and teleoconch characters (see Appendix 1) are comparable between the Recent and fossil samples, warranting the inclusion of Pliocene morphotypes into Montagu’s species. Traces of the original coloration were not visible in examined fossil shells, whereas living specimens are usually buff-coloured.

Figures

FIGURES 1 – 6. Haedropleura septangularis (Montagu). 1 – 3, # 12, Melograni (Siena), Piacenzian (Pliocene); 4 – 6, # 1, Punta Ala (Leghorn), live-collected specimen with operculum. FIGURES 7 – 12. H. secalina (Philippi). 7 – 9, # 43, La Speranza (Siena), Piacenzian (Pliocene); 10 – 12, # 32, Procida (Naples), live-collected specimen with operculum. FIGURES 13 – 18. H. bucciniformis (Bellardi) 13 – 15, # 16, Melograni (Siena), Piacenzian (Pliocene); 16 – 18, # 19, Terre Rosse (Siena), Zanclean / Piacenzian (Pliocene). Scale bars 1 mm; # = shell number in Appendix 1.

FIGURES 49 – 63. SEM photographs of protoconch and of teleoconch details of live-collected and fossil shells. SEM photos are apical and lateral views (scale bars = 0.1 mm). Details (right column) show ornamentation of last whorl of each specimen between suture and aperture, corresponding to the sinus. FIGURES 49 – 54. Haedropleura septangularis (Montagu) 49 – 50, # 4, Capo Comino (Nuoro), Holocene; 51, # 1, Punta Ala (Leghorn), Holocene; 52 – 53, # 11, 54, # 10, Melograni (Siena), Piacenzian (Pliocene). FIGURES 55 – 60. H. secalina (Philippi) 55 – 56, # 37, Ceuta (Spain), Holocene; 57, # 32, Procida (Naples), Holocene; 58 – 60, # 43, La Speranza (Siena), Piacenzian (Pliocene). FIGURES 61 – 63. H. bucciniformis (Bellardi) 61 – 62, # 26, La Serra (Siena), Piacenzian (Pliocene); 63, # 16, Melograni (Siena), Zanclean (Pliocene). # = shell number in Appendix 1.