Wollastonia leacockiana (Wollaston, 1878) Wollaston, 1878

Mattia, Willy De, Neiber, Marco T. & Groh, Klaus, 2018, Revision of the genus-group Hystricella R. T. Lowe, 1855 from Porto Santo (Madeira Archipelago), with descriptions of new recent and fossil taxa (Gastropoda, Helicoidea, Geomitridae), ZooKeys 732, pp. 1-125 : 39-42

Wollastonia leacockiana (Wollaston, 1878) comb. n. Figs 130-132, 133-141, 142

List of synonyms.

1878 Helix (Hystricella) leacockiana Wollaston: 165-167.

1894 Geomitra leacockiana - Pilsbry in Pilsbry 1893-1895: 34.

1931 Geomitra (Actinella) bicarinata var. leacockiana - Nobre: 87.

1950 Discula (Hystricella) leacockiana - Mandahl-Barth: 31, 55.

1983 Discula (Hystricella) leacockiana - Waldén: 20: 267.

2002 Geomitra leacockiana - Bank et al.: 124.

2008 Hystricella leacockiana - Seddon: 79-80, pl. 29 fig. A, map 179.

2011 Hystricella leacockiana - Seddon: e.T6720A12799605.

Type material.

NHM 1875.12.31.137-d, lectotype (herewith designated), from loc. typ., ex coll. T. V. Wollaston; NHM 1875.12.31.137-a to -c and -e, 4 paralectotypes, from loc. typ., ex coll. T. V. Wollaston.

Further material examined.

All from Porto Santo, CWDM/14, CMN/3, Pico de Ana Ferreira, northern slopes near the 'lava columns’, under stones scattered in open grassy fields, 33°02'57"N / 16°22'04"W, 125 m, leg. W. De Mattia & J. Macor, May 2014; CKG/32, CMN/9, Pico de Ana Ferreira, top of the hill, under stones scattered in open grassy fields, 33°02'39"N / 16°22'11"W, 230 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 6 1983; CKG/20, CMN/10, E slope of Pico de Ana Ferreira, 33°02'37"N / 16°22'05"W, 100-200 m, leg. K. & C. Groh, Oct. 26 1980; CKG/1, Ilhéu de Ferro, east side of the island plateau, under stones scattered in open grassy fields, 33°02'19"N / 16°24'26"W, 75 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 2 1983; CFW 11151/<10, N slope of Pico de Ana Ferreira, near the basalt columns, 33°02'57"N / 16°22'03"W, 125 m a.s.l., leg. F. Walther & E. M. Gryl, Mar. 30 2017; CFW 11152/<10 spms, Pico de Ana Ferreira, summit, 33°02'38"N / 16°22'13"W, 230 m, leg. F. Walther, Apr. 4 2017; ANSP H 11838/c. 40, NW slope of the Pico de Ana Ferreira, 33°02'48"N / 16°22'11"W, 190 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 6 1983; ANSP H 11770/ c. 30 [sub H. bicarinata ], E slope of Pico de Ana Ferreira, 33°02'37"N / 16°22'05"W, 100-200 m, leg. J. & C. Hemmen, Jan. 5 1981.

Locus typicus.

Portum Sanctum; in monte 'Pico d’Anna Ferreira’ dicto sat copiose reperta. Necnon in statu semifossili (cum exemplaribus recentibus vix omnino congruens) parcissime occurrit.

Original description.

From Wollaston, 1878: T. trochiformis, subtus planata perforata, undique granulis obtusis densissime obsita, pallide brunneo-subflavescens sed fasciis ( præsertim subtus) nebulisque irregiularibus ( præsertim supra) rufo-brunneis hinc inde suffuse marmorata; spira sat elevata; anfractibus convexis, bicarinatis, ultimi (subtectiformis) carina exteriore acutissima valde exstanti, interior obtusa rotundata recedente rarius obsoleta; umbilico punctiformi; apertura subovali-rotundata, labris continuis conjunctis, peristomate simplici expanso subrecurvo tenui relevato. - Long. axis 1⅔ lin.; diam. 2½.

Redescription of the shell.

The shell is dextral, hairless and it is usually conical and scalariform. The protoconch is from whitish to brown with 1.6 to 1.9 whorls. It is almost smooth along the first half whorl and shows fine radial striae and extremely small, scattered tubercles along its remaining portion. The teleoconch has from 3.9 to 4.4 rapidly increasing whorls. It is variable in colour, from very light brown to brown. The background colour is mottled with brownish to dark-reddish areas, irregularly arranged along the whorls. No band pattern is visible along the upper whorls. On the lower part of the last whorl two more or less indistinct, dark bands are visible. The peripheral band is usually the thinnest and often very indistinct. The spire is usually pyramidal and slightly scalariform. Along the last and partially along the penultimate whorl one evident keel is present. This keel extends along the lower part of the whorls and is usually lighter in colour, sometimes whitish. The external upper surface has very fine but clearly visible, irregularly spaced, growth lines. Irregularly disposed tubercles are present all over the teleoconch. The dimensions of the tubercles tend to slightly increase from the first towards the last whorl, but keeping approximately the same density. The tubercles are somewhat denser along the keel, letting the keel appear like a rough chord. The tubercles usually also concentrate somewhat along the growth lines. On the lower part, the tubercles are much denser along the periphery and gradually become scarcer towards the umbilicus. The last whorl is relatively large and descending near the aperture. The umbilicus is open but very narrow, concentric and measures approximately 10% of the maximum shell diameter. The aperture is elliptical with a quite strong thickening along the inner side of the last whorl. The peristome is continuous, slightly reflected with the columellar margin being somewhat thicker (see Figs 130-132).

Measurements.

D 5.3 ± 0.2 mm (range 5.0-5.6 mm); H 4.0 ± 0.3 mm (range 3.7-4.8 mm); FW 2.6 ± 0.2 mm (range 2.4-2.6); PA 58.8 ± 2.1° (range 55.0-60.0°); DU 0.5 ± 0.1 mm (range 0.4-0.6); NT 49 ± 5 (range 44-56); NW 5.4 ± 0.1 (range 5.3-5.5) (n = 40). Ratio D/H 1.3; ratio FW/H 0.6.

Body.

The head and neck are usually light grey, as is the posterior upper section of the foot. The foot is white and the sole is longitudinally divided into three areas. The central area is smooth, whereas the two lateral areas are equipped with bands of muscles roughly arranged in a chevron pattern. The mantle border is light grey, with five more or less developed lobes. The walls of the pallial cavity are colourless, without any stripes or spots. A strong pulmonary vein is visible. The jaw is odonthognatous and its shape is arched. There are 8 to 10 smooth transverse ridges. The right ommatophoral retractor is independent from both penis and vagina.

Genital anatomy.

The albumen gland is long and it is connected to an approximately equally long sperm-oviduct. The thin vas deferens is approximately as long as the sperm-oviduct. The free oviduct is shorter than the vagina. The duct of the bursa copulatrix is usually thin, approximately as long as the penis and uniform in diameter. The bursa copulatrix is roundish. The transition area between the duct and the bursa itself is very sharply delimited, with the duct abruptly widening and turning into the bursa. The spermatophore is unknown. One tuft of a digitiform glands arises from the proximal part of the vagina. There are two or three glands that are equally long and never branched. A short and thin vaginal appendix arises from the vagina’s wall, just distal of the glandular tuft. The inner surface of the vagina is smooth. The atrium is usually long ( ¾ of the vagina) and relatively thin. Its internal walls are also smooth. The penial flagellum is short, remarkably cylindrical and with a blunt apex. It is usually as long as the epiphallus and its internal walls are completely smooth. The internal walls of the epiphallus are completely smooth as well. The retractor muscle is moderately long, strong and is of variable length. The penis lacks any muscular or glandular sheath. It is thick-walled and approximately three to four times longer than the flagellum. It is usually cylindrical, sometimes slightly swollen and partially folded up. The inner walls of the penis are smooth. The penial papilla is small and bulky. It has smooth external walls with the opening emerging apically but somewhat curving inwards. The channel of the penial papilla is thin and narrow and its cross section is ‘half-moon’ -shaped. The inner lumen of the penial papilla is filled with a spongy and sturdy tissue, which directly connects with the walls of the epiphallus. As all the previous species, the longitudinal section of the penial papilla shows that its walls are the continuation of the penial walls that abruptly bend inward (see Figs 133-141).

Ecology.

Wollastonia leacockiana is commonly found under volcanic rocks and boulders scattered on grassland in open fields that are more or less sloping. The specimens aestivate on the lower surfaces of the rocks, frequently forming clusters of individuals attached one to another.

Distribution.

Wollastonia leacockiana is restricted to Pico de Ana Ferreira and Cabeco da Ponta at the western end of Porto Santo, with records also from Ilhéu de Ferro (CGK), although surveys are required to confirm if the species is still extant on that islet. Seddon (2008: 79, 182) reported the species from a spot at the eastern end of Porto Santo (Ponta do Passo area?). Despite intensive recent field research (WDM 2012, 2014, 2015) the species has not been confirmed in this area. Seddon’s (2008) record could represent a misidentification of a different species (cf. W. klausgrohi sp. n.). The currently known distribution is shown in Fig. 142.

Taxonomic remarks.

As reported by Seddon (2008: 79), Wollaston (1878: 161) separated W. leacockiana from H. bicarinata on the basis of its shell sculpture. This study confirmed Wollaston’s (1878) opinion, as do our molecular analyses and the investigation of the anatomy of the species.

Status and conservation.

The species is currently not significantly impacted by the construction of touristic/residential facilities in its distributional range; only in the Cabeco da Ponta area some new buildings were recently constructed. Recent surveys (WDM, 2012, 2014, 2015) showed that the species is currently widely distributed and common within its range. According to Seddon (2011c) the species is Vulnerable (VU D2), an assessment we regard as appropriate here because of the small range of the species and the potential threat of future construction works in the area. Further research is required to confirm the distribution of the species.