Chondrina maginensis Arrébola & Gómez, 1998

Kokshoorn, Bas & Gittenberger, Edmund, 2010, Chondrinidae taxonomy revisited: New synonymies, new taxa, and a checklist of species and subspecies (Mollusca: Gastropoda: Pulmonata) 2539, Zootaxa 2539 (1), pp. 1-62 : 29-30

Chondrina maginensis Arrébola & Gómez, 1998 (pl. 13 figs E–G)

Type locality: Spain, Andalucia, Sierra Mágina .

Chondrina maginensis Arrébola & Gómez, 1998: 110–113 , fig. 1D (holotype shell), fig. 2B (genital system). Rupestrella maginensis ; Bank, 2003: 15.

Distribution.—Known from the type locality only.

Material.— Spain, Jaén , Cuadros (type locality), near Ermita de Cuadros , on limestone rock along an irrigation canal, 579 m alt., UTM VG6482 ( RMNH 103205 /9, 103207/11); Abánchez de Magina, on rocks at the base of Castillo de Abánchez, 974 m alt., UTM VG5882 ( RMNH 108829 / 6 in alcohol 70%) .

Shell (n=11).—Shell very slender, regularly conical, with c. 8, yellowish brown whorls; height 5.7–6.4 mm, height-width ratio 2.9–3.4.

Protochonch more conspicuous than usual in Chondrina , nearly as broad as the adjoining teleoconch whorl, with 1½–1¾ strongly inflated, clearly granular whorls. Teleoconch whorls more or less regularly sculptured with prominent riblets that are separated by wider interspaces. Initial teleoconch whorls convex, separated by a deep suture; final quarter to half of the body whorl obliquely flattened, sometimes with a vague indentation, corresponding with the position of the palatalis superior inside. Apertural lip with a short (half the apertural width) interruption at the parietal side, not or hardly reflexed but slightly thickened by a white callus, regularly rounded basally; palatal side nearly parallel with the columellar axis and columellar side obliquely deviating. Apertural height 1.6–1.7 mm, height/width ratio 1.1–1.4.Apertural lamellae more or less rudimentary. The columellaris is the most prominent lamella; it does not extend beyond the columella and may be accompanied by a weak subcolumellaris (most clearly seen in oblique view). The angularis may be about as prominent as the parietalis, but is usually more obsolete. Palatal lamellae are usually absent, apart from one or even two very weak thickened streaks. According to Arrébola & Gómez (1998) however, the palatal lamellae may be more prominent. The umbilicus is widely open.

Genitalia (n=2) (fig. 8 A, B).—The length of the vagina is about five times its width; it is somewhat longer than the oviduct and about as long as the part of the penis that is situated outside the penial loop. The spermoviduct is about one and a half times longer than the combined vagina and oviduct. The peduculus of the bursa copulatrix is long and slender; the tip of the bursa touches the glandula albuminifera. The male part of the genital tract forms a loop as in other chondrinid species ( Gittenberger 1973). The penis is here defined as the simple, tube-like structure, which reaches from the genital atrium far into the loop, ending with a short, abruptly narrowing segment, after which the epiphallus starts. Inside the most proximal part of the epiphallus there is a vague pattern of some septae. The distal end of the epiphallus is attached to the penis about as far as the length of the vagina from the genital atrium.

Radula (n=2) (fig. 8 C).—The central tooth can be recognized because of its symmetrical basal plate, with a supporting denticle at each side. Next to the unicuspid central tooth there are five or six unicuspid lateral teeth, followed by two or three laterals with a more or less vaguely discernible ectocone. The adjoining marginal teeth, ranging from tooth 9 to 20, are prominently bicuspid and increasingly more irregularly comb-like towards the radular margin, with tooth no. 20 being hardly recognizable as a tooth.

Genetic barcode.—Three partial (598bp) Cytochrome Oxidase subunit I sequences were produced ( Kokshoorn 2008). One specimen from the type locality, GenBank accession no. FJ171596 , and two from Abánchez, GenBank accession nos FJ171597 and FJ171598 .

Discussion and conclusions.—Because of its shell shape and size, Chondrina maginensis has been classified with Rupestrella by Bank (2003: 15). However, shell shape in Rupestrella is very variable. Species with a slender conical shell, like for example R. rhodia ( Roth, 1839) , are classified in Rupestrella indeed, but next to species like R. philippii ( Cantraine, 1840) , with a shell that has a spire with slightly convex sides and a more cylindrical lower part. In Chondrina , C. marmouchana was considered rather different from the congeneric species by its slender conical shell ( Gittenberger 1973: 251), which reminds of that in C. maginensis . Molecular data ( Kokshoorn et al. 2010), however, make clear that the conchological similarity between C. marmouchana and C. maginensis is due to convergent evolution. In size, C. maginensis could be considered either a large Rupestrella or a small Chondrina . The apertural teeth of the shell cannot be considered diagnostic for either Chondrina or Rupestrella , since in Chondrina these teeth vary from none to several. The structure of the genital tract can also not be used to discriminate between these two genera. According to Gittenberger (1973: 21, 23), only the radula is known to be diagnostic for Chondrina versus Rupestrella species. In species of the former genus, the central tooth in each row can only be recognized unequivocally by the symmetrical structure of its basal plate, which has a support knob at each side. The central tooth and the adjoining lateral teeth cannot be distinguished at first sight because they all have a single main cusp without any side cusps. This bauplan is found in C. maginensis (fig. 8c), which supports its classification in Chondrina , not Rupestrella . The molecular data confirm that C. maginensis has to be considered a Chondrina species. Its resemblance to Rupestrella species , like R. rhodia might be considered more meaningful, viewed in the light of its phylogenetic position in Chondrina as the sister-group to all other extant Chondrina taxa, suggesting that the species retains some plesiomorphic shell characteristics. Apart from the somewhat unusual shell shape and its surprising phylogenetic relationships as the sister-taxon of the combined other Chondrina taxa, nothing is known that adds to the oddity of C. maginensis .

Distribution.—The species is known only from the north flank of the Sierra Mágina in the province of Jaén, Andalucia, Spain. The original description by Arrébola & Gómez (1998) lists two localities, viz. the type locality, Cuadros, and the village of Jódar, which lies app. 6 km NE of the type locality. The actual sampling localities have not been mentioned. During fieldwork in 2006 another two localities were added, viz. Torres, c. 4 km W of Cuadros, and Abánchez de Magina, situated approximately 5 km W of the type locality. A sample was taken from limestone rocks at the base of Castillo de Abánchez (UTM VG5882), situated at 974 m, which is the highest altitude at which the species has been found so far.

Figures

FIGURE 2. Distribution of Abida secale subspecies (I) in NE Spain and Andorra.