Monilearia

Neiber, Marco T., 2015, On the generic placement of the narrow-range endemic ‘ Helix ’ arguineguinensis Seddon & Aparicio, 1998 from Gran Canaria (Canary Islands), Zootaxa 3981 (2), pp. 296-300 : 297-299

Subgenus Monilearia s. str.

Monilearia (Monilearia) arguineguinensis ( Seddon & Aparicio, 1998)

Synonyms. Helix argonautula var. canariensis Mousson, 1874 (non Helix (Xerophila) canariensis Mousson, 1872 and Helix (Macularia) lactea var. canariensis Mousson, 1872 ). For further synonyms, see Seddon & Aparicio (1998).

FIGURE 1. Schematic representations of the generalized penial appendage of orthurethran gastropods (A) and the vagianal appendage of genera in Cochlicellini: Obelus Hartmann, 1842 (B), Monilearia Mousson, 1872 (C), Cochlicella Férussac, 1821 (D), and Prietocella Schileyko & Menkhorst, 1997 (E) (after Ibáñez et al., 2003), and genital system (F) of Monilearia (Monilearia) arguineguinensis ( Seddon & Aparicio, 1998) . Abbreviations: A1–A5, sections of generalized penial appendage of orthurethran gastropods and sections of vaginal appendage of Cochlicellini; ag, albumen gland; at, genital atrium; bc, bursa copulatrix; ep, epiphallus; f, flagellum; hd, hermaphroditic duct; p, penis; rm, retractor muscle; sov, spermoviduct; v, vagina; vd, vas deferens.

Material examined. Spain, Canary Islands, Gran Canaria, settlement E of Argüineguin, 27°45’38’’ N, 15°40’04’’ W, 50 m a.s.l., February 2015, E. Schlegel leg. (1 shell, MN GEO-045 and 2 preserved specimens, ZMH 92264); Spain, Canary Islands, Gran Canaria, coll. Melvill-Tomlin, ex Wollaston (1 shell, NMW 1955.158.02113); Spain, Canary Islands, Gran Canaria, Argüineguin, syntype coll. Mousson, ex Wollaston (4 shells, syntypes of Helix argonautula var. canariensis Mousson, 1874 and of ‘ Helix ’ arguineguinensis Seddon & Aparicio, 1998 , ZMZ 505021).

Description. A detailed description of the shell ( Fig. 2 A) is given in Wollaston (1878) or Seddon & Aparicio (1998) and therefore is not repeated here. Genitalia (Fig. 1F): Right ommatophoran retractor independent of genitalia. Atrium short (0.9 mm), about as long as vagina (0.8 mm) and free oviduct (0.8 mm), the latter about as wide as vagina. Spermoviduct (4.0 mm) with a light touch of dark pigment, albumen gland withish, tongue-shaped (2.8 mm), hermaphroditic duct light-brownish, slightly undulating. Bursa copulatrix complex adhering to spermoviduct, with a long duct (3.2 mm) and an oval bursa (1.1 mm). Penis very short (0.6 mm), inflated, internally with a plug-shaped penial papilla with apical pore; epiphallus (6.2 mm) about 10 times as long as penis, retractor muscle inserting in its distal fifth (in relation to the position of the hermaphroditic gland). Flagellum (2.1 mm), thin, about 1/3 the length of epiphallus.

Vaginal appendage well developed, with a hook-shaped, broad A1 section (2.9 mm); A2 section short (0.4 mm), slightly bent and well muscularized; A4 section 2.8 mm long and thin, the branched A5 section (2.8 mm) split into three thin ducts that are about as long as the A4 section. Internal wall of genital atrium equipped with several rugose, longitudinal pilasters that can be traced into the vagina and the vaginal appendage, in the latter two stronger and several weaker pilasters are discernible.

Remarks. The structure of the vaginal appendage of M. arguineguinensis (Fig. 1) corresponds to that observed in other species assigned to the genus ( Hesse, 1911; Odhner, 1932; Schileyko & Menkhorst, 1997; Ibáñez et al., 2006). Ibáñez et al. (2006) included three species in Monilearia (Lyrula) Wollaston, 1878 on the basis of a similar shell sculpture consisting of a decussate ornamentation of slightly undulating radial riblets and numerous (sometimes stronger) spiral lines. The shell of M. arguineguinensis ( Fig. 2 ) has a well-developed radial ornamentation consisting of numerous, irregular riblets, but spiral lines are absent. Therefore, M. arguineguinensis is included in the nominate subgenus here. Seddon & Aparicio (1998, p. 19) clearly intended the name ‘ Helix ’ arguineguinensis as a new replacement name for the variety from the Canary Islands introduced by Mousson (1874), i.e. for Helix argonautula var. canariensis (not Helix canariensis Mousson, 1872 or Helix lactea var. canariensis Mousson, 1872 ). Although Seddon & Aparicion (1998, p. 21) attributed the name ‘ canariensis ’ erroneously to Wollaston (1878), the reference to the combination used by Wollaston (1878), Disculus argonautula var. canariensis ( Mousson, 1874) , in the synonymy of ‘ H. ’ arguineguinensis makes it clear, which name the authors replaced by the new name. According to the ICZN code Art. 72.7 both nominal taxa have the same name-bearing type despite any contrary designation. Seddon & Aparicio (1998) designated a shell from the Mellvill-Tomlin collection (NMW 1955.158.0 2113, see also Fig. 2 B) as lectotype of ‘ Helix ’ arguineguinensis . However, there are four shells labelled as H. argonautula var. canariensis in the Mousson collection at Zurich (ZMZ 505021, see also Fig. 2 C) which are syntypes of H. argonatula var. canariensis and according to ICZN Art. 72.7 also of ‘ H.’ arguineguinensis . There is no evidence that the specimen from the collection in Cardiff (NMW 1955.158.02113) was known to Mousson when introducing the name H. argonatula var. canariensis and therefore it cannot be regarded as belonging to the syntypes series. Hence, I regard its selection as lectotype as invalid (ICZN Art. 74.2) and only the shells in the Mousson collection at Zurich (ZMZ 505021) have type status.

Figures

FIGURE 2. Shells of Monilearia (Monilearia) arguineguinensis (Seddon & Aparicio, 1998). A) Spain, Canary Islands, Gran Canaria, settlement E of Argüineguin, 27 ° 45 ’ 38 ’’ N, 15 ° 40 ’ 04 ’’ W, 50 m a. s. l., leg. E. Schlegel (ZMH 92264), B) Spain, Canary Islands, Gran Canaria, coll. Melvill-Tomlin, ex Wollaston (NMW 1955.158.02113), C) Spain, Canary Islands, Gran Canaria, Argüineguin, syntype coll. Mousson, ex Wollaston (ZMZ 505021). Photographs: A) F. Walther, B) Copyright Amgueddfa Cymru - National Museum Wales C) Copyright CSCF Neuchâtel, E. Neubert. Scale bar: 5 mm.