Napaeus venegueraensis Artiles, Santana & Deniz, 2011

Yanes, Yurena, Santana, Jesús, Artiles, Miguel, Deniz, Francisco, Martín, Javier, Alonso, María R. & Ibáñez, Miguel, 2011, Five new Napaeus species (Gastropoda: Pulmonata: Enidae) from Gran Canaria and El Hierro (Canary Islands), Zootaxa 2901 (1), pp. 35-51 : 43-46

Napaeus venegueraensis Artiles, Santana & Deniz , n. sp.

Figs. 1 , 3 D, G , 5 C, D , 7 A–C , 8 A

Type locality. Barranco de Veneguera (Gran Canaria; UTM: 28RDR 2583, 100 m altitude).

Holotype ( Fig. 3 D ; empty shell): TFMC ( MT 0416 ). Leg. M. Valido and M. Ibáñez, 29 December 1988.

Paratypes. 3 specimens and 107 shells, collected between 1988 and 2010 from the south of Gran Canaria ; deposited in AIT and the following collections: FDGC (7 shells); JSGC (67 shells); MAGC (20 shells) .

Etymology. The specific name is derived from its type locality, Veneguera.

Distribution and habitat ( Fig. 1 ). Endemic to Gran Canaria, occupying an area of about 200 km 2 of the south of the island, associated mainly with lowland vegetation and also pine forest, within an altitudinal range between 80 and 715 m. Napaeus venegueraensis is mainly a ground dweller, living in pine forest and “cardonal” ( Euphorbia canariensis L.), sheltering during the day under stones or between Euphorbia roots. Some specimens collected together with N. josei in the Barranco del Lechugal had the shell disguised by a thick soil covering, but N. venegueraensis has usually been found undisguised.

Diagnosis. Shell ovate, with whorls increasing regularly in size. Teleoconch ribbed with protuberances irregularly distributed on first whorls and regularly placed on the body whorl. Epiphallus with epiphallic caecum. Penial appendix slightly shorter than penis and epiphallus together. Bursa copulatrix duct similar in length to or slightly shorter than diverticulum.

Description. Body pale brown, covered with brown spots, denser in cephalic area. Shell ( Fig. 3 D ) dextral, robust, obese (SB/SH index), ovate, cone-shaped above, with whorls increasing regularly in size, 6½–7 weakly convex whorls separated by shallow sutures. Body whorl intermediate (BH/SH index), occupying less than ⅔ of the shell surface area (BS/SS index). Protoconch smooth, shiny, with 1½–1¾ whorls. Aperture long, wide (AH/SH and AB/SB indices, respectively), with elliptical section at palatal side, more curved at junction of columellar and palatal edges. Angle ( Fig. 2 ) between columella and upper palatal margin about 135º. Peristome discontinuous, moderately expanded as whitish lip, more developed in lower part of palatal edge, reflected on columellar edge, partly covering umbilical slit. Older specimens with a callosity between peristome edges and a nodule at junction of parietal and palatal margins. Aperture extending laterally beyond penultimate whorl by about 22% (ca 0.74 mm).

Shell colour pale brown. Ornamentation characterised by numerous oblique, sinuous radial ribs, interrupted on the first teleoconch whorls forming irregularly distributed protuberances, whereas they are regularly placed on the body whorl ( Figs. 5 C, D ).

Genital system ( Fig. 8 A ; three specimens dissected). Atrium very short. Penis about a quarter of the length of the epiphallus, with two portions. Distal portion tubular, located between atrium and insertion of penial retractor muscle. Proximal portion swollen. Epiphallus tubular, opening distally into penis, two regions of similar length defined by presence of epiphallic caecum. Flagellum very short. Vas deferens thicker in its distal portion. Penial appendix arising in distal portion of penis near genital orifice, slightly shorter than penis and epiphallus together. Part A 1 of penial appendix clearly differentiated from globular part A 2, similar in length to penis. Appendicular retractor muscle inserting laterally in middle zone of part A 1, joined to penial retractor on diaphragm walls. Part A 3 more slender, shorter than proximal A 1 portion. Parts A 3 and A 4 clearly separated from each other; A 4 long, distally very thin, passing gradually into expanded A 5.

Free oviduct shorter than vagina. Vagina firmly fixed to body tegument by short connective fibres. Bursa copulatrix complex with well-developed diverticulum, branching off near proximal end of bursa duct, more slender and similar in length to or slightly longer than bursa duct.

Comparison with other taxa. Shell morphology: The shell shape of N. venegueraensis n. sp. ( Fig. 3 D ) is comparable mainly to that of N. obesatus (Webb & Berthelot, 1833) , from Gran Canaria ( Fig. 3 G ), and N. bajamarensis Ibáñez & Alonso, 2009 , from Tenerife ( Fig. 3 H ). The last two species are similar to each other in dimensions and clearly bigger than N. venegueraensis ( Figs. 3 G, H , 7 A ). The three species differ also in shell ornamentation, N. venegueraensis being rough, without gloss, with the radial ribs irregularly distributed on the first teleoconch whorls ( Figs. 5 C, D ); N. obesatus has the ribs more widely spaced and regularly disposed ( Fig. 3G ), and N. bajamarensis has the teleoconch almost smooth ( Fig. 3 H ).

Genital anatomy: N. venegueraensis is similar to N. bajamarensis ( Yanes et al., 2009, fig. 9), but the latter species has an exceptionally long bursa copulatrix duct, several times longer than the diverticulum. In contrast, the bursa duct of N. venegueraensis is similar in length to or slightly longer than the diverticulum. The proximal penis portion of N. venegueraensis is more swollen than that of N. bajamarensis .

Figures

FIGURE 1. Geographical distribution of the new species.

FIGURE 2. Drawings of the shell of the holotype of Napaeus arinagaensis n. sp., showing the placement of the measurements obtained (in º, 2 mm or mm). α, upper palatal angle (i.e. the angle between the columella and the upper palatal margin of the aperture); AB, aperture breadth; AH, aperture height; AP, aperture perimeter; AS, aperture surface area (plane view); BH, body whorl height (at columella level); BP, body whorl perimeter; BS, body whorl surface area (plane view); FB, first whorls breadth; FH, first whorls height; FP, first whorls perimeter; FS, first whorls surface area (plane view); PB, penultimate whorl breadth; PH, penultimate whorl height; PP, penultimate whorl perimeter; PS, penultimate whorl surface area (plane view); SB, shell breadth; SH, shell height; SP, shell perimeter; SS, shell surface area (plane view); T, distance between columella and periphery of penultimate whorl above aperture; U, highest distance between columella and palatal edge of aperture.

FIGURE 3. Shells of: A. Napaeus josei n. sp., holotype. B. N. nanodes, from Barranco del Agua, Tenerife (AIT). C. N. badiosus, from Barranco de Valle Seco, Tenerife. D. N. venegueraensis n. sp., holotype. E. N. chrysaloides, from Tamadaba, Gran Canaria (AIT). F. N. validoi n. sp., holotype. G. N. obesatus, from Barranco del Pagador, Gran Canaria (AIT). H. N. bajamarensis, holotype (from Yanes et al. 2009). J. N. grohi n. sp., holotype. K. N. osoriensis, from Osorio, Gran Canaria (AIT). L. N. myosotis, from Montaña de Guía, Gran Canaria (AIT). M. N. exilis, from Altos de Gáldar, Gran Canaria (AIT). N. N. arinagaensis n. sp., holotype. O. N. moquinianus, from Brezal del Palmital, Gran Canaria (AIT). P. N. isletae, holotype.

FIGURE 5. Details of shell ornamentation of holotypes (A, C: penultimate whorl; B, D: body whorl). A–B. Napaeus josei n. sp. C–D. N. venegueraensis n. sp.

FIGURE 7. Scatter plots of some shell measurements for the new species and the most similar species. AS, aperture surface area (plane view); BS, body whorl surface area (plane view); FS, first whorls surface area (plane view); PS, penultimate whorl surface area (plane view); SB, shell breadth; SH, shell height; SS, shell surface area (plane view). The dimensions are in mm (lengths) or mm2 (surface areas).

FIGURE 8. Genital systems of: A. N. venegueraensis n. sp., paratype from Barranco de Taurito, Gran Canaria (AIT). B. N. validoi n. sp., paratype from Monte de Inagua, Gran Canaria (AIT). A1–A5, parts of the penial appendix; bc, bursa copulatrix; d, diverticulum; dp, distal penis; e, epiphallus; ec, epiphallic caecum; f, flagellum; go, genital orifice; o, free oviduct; par, penial appendix retractor; pp, proximal penis; pr, penis retractor; v, vagina; vd, vas deferens.