Hemicycla (Hemicycla) fuenterroquensis, Castro, Juan M., Yanes, Yurena, Alonso, Maria R. & Ibáñez, Miguel, 2012

Castro, Juan M., Yanes, Yurena, Alonso, Maria R. & Ibáñez, Miguel, 2012, Hemicycla (Hemicycla) fuenterroquensis (Gastropoda: Helicoidea: Helicidae), a new species from La Palma, Canary Islands, Zootaxa 3527, pp. 72-78 : 73-74

Hemicycla (Hemicycla) fuenterroquensis sp. nov.

Type locality. Fuente de los Roques, La Palma. UTM: 28RBS 2257, 880 m a.s.l..

Holotype (shell): TFMC (MT0841; Fig. 2 C, Table 1), Leg. J. M. Castro, 15th April 2012.

Paratypes. 1 ethanol specimen and 25 shells (AIT), 94 shells (JMC) and 5 shells (RG), collected between 24th April 2011 and 5th May 2012 at the type locality and its surroundings.

Etymology. The specific epithet refers to the name of the type locality of the new species.

Distribution and habitat ( Fig. 1 ). The species is endemic to La Palma. It is present between 50–1160 m (a.s.l.). Living specimens were found exclusively between 830–1160 m (a.s.l.) in a dry pine forest of the Fuente de los Roques area, which is exposed to the moist trade winds from the Northeast. This locality is situated in the Southeast of the dorsal chain of the Cumbre Vieja Mountains. A part of these mountains belongs to the Cumbre Vieja Natural Park.

Description. Body dark blue-greyish coloured dorsally, more bluish laterally ( Fig. 1 ), sole greyish. Jaw odontognathous with 6 ribs, the two central ribs are the most developed, while the two outer ribs are almost inconspicuous.

Shell ( Fig. 2 C; Table 1) imperforate, unkeeled, depressed globular, with soft shine, about 4 ¼ convex whorls and well-marked sutures, protoconch with about 1 ¼ whorls. Shell colour on the dorsal side reddish-brown but with two wide, diffuse darker brown spiral bands occupying the dorsal surface almost completely; the colour of the ventral side is corneous, with one or two narrow spiral bands, also of a darker brown colour. Aperture oblique and rounded, without angulations, the margins barely converge at the insertion. White peristome largely reflected covering the umbilicus in adult specimens (juvenile specimens have it open and subadults have an opened split).

Shell ornamentation ( Fig. 2 D). The protoconch is almost smooth, with minute radial folds. The teleoconch has many radial folds regularly arranged on the dorsal side near the suture, but a short distance below the suture the folds join irregularly, making up a well developed malleation. The shell surface has a faint microsculpture ( Fig. 2 D, arrows) of very weak radial and spiral folds, ocassionally, where the radial and spiral folds intersect, a very weak microgranulation is developed.

Genital system ( Fig. 4 B; 3 specimens dissected): Atrium short. Bursa copulatrix complex with a well developed diverticulum, near 4/3 times longer than the bursa duct and up to 3 times longer than the common stalk. The bursa copulatrix is globular. The dart sac is accompanied by a pair of mucus glands, each one with 3–4 long terminal tubules. The penial complex has a long flagellum, slightly shorter than the bursa copulatrix diverticulum and more than twice longer than penis and epiphallus together. The retractor muscle has an epiphallar insertion.

The penis has a system of twin papillae with a penial chamber between them ( Fig. 4 B), similar to those described for other Hemicycla species (Alonso & Ibáñez, 2007, Ibáñez & Alonso, 2007) and several other genera of the subfamily Helicinae ( Neubert & Bank, 2006).

TABLE 1. Shell dimensions (in mm or mm2) of the three Hemicycla species from La Palma Island. BH, body whorl height (at columella level); BP, body whorl frontal perimeter; BS, body whorl frontal surface (plane view); D1, maximum shell diameter; D2, shell diameter perpendicular to D1; FP, shell frontal perimeter; FS, shell frontal surface (plane view); SH, shell height; SP, shell perimeter (dorsal plane view); SS, shell surface (dorsal plane view); n, number of specimens measured.

Figures

FIGURE 1. Geographical distribution of the known Hemicycla species from La Palma Island, and a detailed photograph of a Hemicycla fuenterroquensis sp. nov. specimen described in the present study.

FIGURE 2. Shells and details of the body whorl ornamentation of the three known Hemicycla species from La Palma Island. A, B, Hemicycla vermiplicata; C, D, H. fuenterroquensis sp. nov.; E, F, H. granomalleata. The arrows in Fig. 2 D highlight the weak microsculpture of the H. fuenterroquensis sp. nov. shell.

FIGURE 4. Genital system. A, Hemicycla vermiplicata; B, H. fuenterroquensis sp. nov.; C, H. granomalleata; bc, bursa copulatrix; bd, bursa duct; cs, common stalk of the bursa copulatrix complex; d, diverticulum; ds, dart sac; e, epiphallus; f, flagellum; go, genital orifice; pp 1, proximal penial papilla; pp 2, distal penial papilla; pc, penial chamber; r, retractor muscle.