Coneuplecta Moellendorff, 1893

Coneuplecta Moellendorff, 1893 View in CoL

Coneuplecta Moellendorff, 1893: 64 View in CoL . Type species Helix scalarina Pfeiffer, 1851 [ nom. nov. for Helix gradata Pfeiffer, 1846 non Gould, 1846] (SD Moellendorff, 1898). Island of Leyte, Pacific.

Description. External morphology: Shell 4.1–5.1 whorls, not glossy, spire and apex raised. Shell not glossy. Protoconch sculptured with spiral and radial ribs ( Coneuplecta calculosa , C. pampini ) or spiral grooves ( C. dahli ); teleoconch with spiral and radial lirae. Whorl profile flattened above and below evenly convex periphery. Internal walls of early whorls complete; umbilicus closed. Mantle laps and lobes absent. Sole of foot tripartite; caudal apparatus formed from curled up sole ( Muratov’s 1999 helicarionid type); caudal foss horizontal slit in tail.

Mantle cavity: Kidney unilobed; mantle with no visible minor blood vessels, pigmentation of black and white spots ( C. calculosa ), numerous white spots ( C. pampini ) or absent ( C. dahli ), mantle gland present ( C. calculosa ) or absent ( C. dahli ) (not examined in C. pampini ).

Digestive system: Oesophageal crop absent.

Genital system: Oviparous; carrefour and talon both not embedded in albumen gland. Oviduct glandular. Free oviduct long to very long; capsular gland present ( C. calculosa ) or absent ( C. pampini ) (not examined in C. dahli ); internal longitudinal pilasters absent. Bursa copulatrix inserted on vagina, very short, shorter than free oviduct ( C. calculosa , C. dahli ) or short, approximately equal in length to free oviduct ( C. pampini ); duct of bursa copulatrix wide, not distinguishable from bursa copulatrix ( C. calculosa ) or narrow, distinguishable from bursa copulatrix ( C. pampini , C. dahli ). Vagina very short ( C. dahli ) or short ( C. calculosa , C. pampini ), internally smooth. Stimulator absent ( C. dahli , C. pampini ) or basal diverticulum on penis (vestige of stimulator?) present ( C. calculosa ). Epiphallus enters penis through simple pore ( C. calculosa , C. dahli ) or verge ( C. pampini ), penis internally smooth ( C. calculosa , C. pampini ) or with ridges ( C. dahli ), pilasters absent. Penial sheath present, enclosing only penis. Epiphallus shorter than ( C. calculosa , C. dahli ) or longer than ( C. pampini ) penis. Epiphallic retractor caecum absent. Flagellum and lime-sac absent. Spermatophore not present in dissected specimens.

Radula ( C. calculosa , C. pampini only): Wide, with no lateral wrinkles. Central tooth with large ectocones and two smaller accessory cusps ( C. calculosa ) or with small, high, triangular ectocones ( C. pampini ); mesocone long and narrow, shorter than tooth base. Two ( C. calculosa ) to no ( C. pampini ) lateral teeth present, distinguished from marginals only by presence of endocones; marginal teeth with endocones absent; ectocones approximately same length and breadth as mesocone, subdivided into 2–5 extra teeth, increasing in number towards the outer edge ( C. calculosa ) or ectocones not subdivided but with 5–9 serrations, increasing in number and becoming deeper towards outer edge ( C. pampini ).

Remarks. As outlined by Solem (1988), Coneuplecta was redefined by Baker (1941a) who included in it several subgenera, including Durgellina Thiele, 1928 and Conibycus Thiele, 1928 , all with somewhat diverse shells but similar anatomical features. Solem (1988) followed this usage. This arrangement is tentatively followed here.

Nevelasta was named for Helix pampini Cox, 1868 and Helix ( Conulus) liardeti Brazier, 1872 ( Iredale 1937c) . The type of the latter species is missing and it was placed under incertae sedis by Smith (1992), effectively leaving Nevelasta as a monotypic genus. Nevelasta was originally placed in the family Durgellidae along with Turrisitala Iredale, 1933 , Sodaleta Iredale, 1937 and Eclipsena Iredale, 1937 ( Iredale 1937c) . It was placed in Helicarionini (Helicarioninae, Helicarionidae ) by Schileyko (2002b) based on shell details.

The Australian species Nevelasta pampini is included in Coneuplecta s.l. based on similarities in its shell, anatomy and radula to Coneuplecta calculosa , C. microconus (Mousson, 1865) and C. turrita palauensis Baker, 1941 . The distinctive wide radula with V-shaped tooth rows and small to absent lateral tooth fields is seen in these members of Coneuplecta ( Baker 1941a; this study). However, C. ( N.) pampini differs from the other taxa in the presence of a tricuspidate rather than a pentacuspidate central tooth, two cusps and minor serrations on the latero-marginal teeth rather than four to five, and more rounded cusps ( Figure 40A–C View FIGURE 40 ). For this reason this species is tentatively retained in the subgenus Nevelasta .

In the phylogenetic analysis, the three species included in Coneuplecta always grouped together ( Figures 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ) and formed the most basally diverging taxon in the ingroup.