Napaeus grohi Alonso, Ibáñez & Santana, 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 : 48-49

Napaeus grohi Alonso, Ibáñez & Santana , n. sp.

Figs. 1 , 3 J , 7 A–C , 9 C , 10

Type locality. Pista del Derrabado (El Hierro; UTM: 28RDR 6182, 850 m altitude).

Holotype. ( Fig. 3 J ; ethanol-preserved specimen): TFMC ( MT 0419 , shell and dissected soft body). Leg. M. Ibáñez, 5 January 1993 . Paratypes. 2 shells ( JSGC) collected in 2006 from the Ermita de La Caridad and Lomo Blanco (northwest of the island); deposited in the JSGC collection .

Etymology. The specific name is dedicated to our friend Klaus Groh, who has spent several decades working in malacology.

Distribution and habitat ( Fig. 1 ). Endemic to El Hierro, occupying an area of about 10 km 2 of the humid laurel forest on the El Golfo northern slopes, within an altitudinal range between 850 and 1200 m. This species is a ground-dweller, associated with the humid laurel forest.

Diagnosis. Shell obese, conic-ovate, with weakly convex whorls increasing regularly in size and shallow but distinct suture. Body whorl large. Aperture with five-sided appearance. Penis globose, without penial papilla but with sphincter between epiphallus and penis. Penial cavity with eight longitudinal, wrinkled folds, four of these thickened and alternating with the other four. Penial retractor muscle inserting on distal end of penis. Bursa copulatrix very large, pear shaped, without diverticulum.

Description. Body brown, covered with blackish-brown spots, denser in cephalic area. Shell ( Fig. 3 J ) dextral, obese (SB/SH index), conic-ovate, with whorls increasing regularly in size, 6½–7 weakly convex whorls. Body whorl large (BH/SH index), comprising almost ¾ of shell surface area (BS/SS index). Protoconch smooth, shiny, with 1½ whorls. Aperture long and wide (AH/SH and AB/SB indices). Angle ( Fig. 2 ) between columella and start of upper palatal margin about 120º; upper palatal margin transitioning into central part of palatal margin with a rounded, blunt angle (ca. 50º), so that the central part is almost parallel with the columella; (angle between them ca. 170º); junction of palatal and columellar edges also slightly angular, resulting in a five-sided appearance of the aperture. Peristome discontinuous, expanded as moderate whitish lip, more developed in lower part of palatal edge and reflected on columellar edge, partly covering umbilical slit. Holotype with callosity between peristome edges and small nodule at junction of parietal and palatal margins. Aperture extending laterally beyond penultimate whorl by about 28% (ca 0.95 mm).

Shell colour pale-brown, with first whorls darker than rest. Shell ornamentation almost smooth, characterised by numerous weak, radial oblique ribs ( Fig. 9 C ). Shell with gloss despite ribs.

Genital system ( Fig. 10 ; only one specimen dissected, the holotype). Atrium very short. Penis globose, without sections, about one-third the length of epiphallus, without penial papilla but with sphincter between epiphallus and penis. Penial cavity with eight longitudinal, wrinkled folds, four of them thickened and alternating with the other four which are narrower. Penial retractor muscle inserting on distal end of penis. Epiphallus tubular, not subdivided into portions, opening distally into penis. Flagellum short. Vas deferens opens laterally into proximal end of epiphallus. Penial appendix arising from distal portion of penis near atrium, slightly shorter than penis and epiphallus combined. Part A 1 of penial appendix short, tubular, clearly differentiated from globular part A 2. Short appendicular retractor muscle inserting laterally in middle zone of part A 1, joined to short penial retractor on diaphragm walls. Part A 3 slender, shorter than penis. Part A 4 shorter and more slender than A 3, passing gradually into expanded and longer A 5. Free oviduct three to four times longer than vagina. Vagina firmly attached to body tegument by short connective fibres. Bursa copulatrix complex without diverticulum, vesicle pear shaped, very large, ca. twice as long as wide; bursa duct tubular and very thick.

Comparison with other taxa. Shell morphology: Napaeus grohi ( Fig. 3 J ) is comparable in form and size with N. josei ( Fig. 3 A ) and N. badiosus ( Fig. 3 C ), its whorls being flatter and the ornamentation weaker than in both of those species. In N. josei the shell is broader and in N. badiosus it is more slender (excluding the aperture) than in N. grohi .

Genital anatomy: N. grohi differs from all species of the genus for which the anatomy is known by the insertion of the penial retractor muscle on the distal end of the penis, near the genital orifice and by the very large, pear shaped vesicle of the bursa copulatrix complex.

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 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 9. Details of shell ornamentation of holotypes (penultimate whorl). A. Napaeus arinagaensis n. sp. B. N. validoi n. sp. C. N. grohi n. sp.

FIGURE 10. Napaeus grohi n. sp., holotype. A. Genital system. B. Detail of the flagellum. C. Internal anatomy of penis. A4–A5, parts of the penial appendix; ag, albumen gland; bc, bursa copulatrix (although this appears be bent it is in fact only wrinkled); e, epiphallus; f, flagellum; go, genital orifice; o, free oviduct; par, penial appendix retractor; p, penis; pr, penis retractor; sph, sphincter between epiphallus and penis; v, vagina; vd, vas deferens.