Orpiella (Kalendyma) concavum
Creators: name: Hyman, Isabel T.
name: Ponder, Winston F.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Stylommatophora
Trochomorphidae
Orpiella
Orpiella concavum

description: Orpiella (Kalendyma) concavum (Clapp, 1923)   
Figures 33L, 37E–F, 41D, 42J–L  
 Material examined. Solomon Islands: BMNH no number (Acc no. 2181, no. JP104) (two specimens dissected, radulae examined), near Ribi Caves, Auki, Malaita, foliage.   
 Description. External morphology: Shell 5 whorls, pale golden brown, glossy, spire and apex slightly raised. Protoconch smooth; teleoconch sculptured with broad, flat, moderately widely spaced radial ribs. Whorl profile rounded above and flattened below a slightly angular periphery. Internal walls of early whorls complete; umbilicus closed. Animal beige with multiple black spots on sides of foot and black stripes leading to eyestalks. Mantle laps absent; mantle lobes very small. Sole of foot tripartite; caudal apparatus formed from curled up foot (Muratov’s 1999 helicarionid type). Caudal horn of medium size; caudal foss vertical slit in tail.   
 Mantle cavity: As for family. Mantle pigmentation of black and white spots, mantle gland absent.   
 Digestive system: Oesophageal crop absent.   
 Genital system (Figures 33L, 37E–F, 41D): As for family. Carrefour free of albumen gland, carrefour embedded. Free oviduct long; capsular gland present; internal longitudinal pilasters absent. Bursa copulatrix inserted on vagina, moderately short, about half spermoviduct length; duct of bursa copulatrix wide, distinguishable from bursa copulatrix, internally with longitudinal pilasters. Vagina very short; internally with longitudinal pilasters. Penis short; epiphallus enters penis through simple pore; penis internally smooth, six to seven longitudinal penis pilasters present, penial diverticulum absent. Penial sheath present, thin, enclosing only penis; penis retractor muscle attached to epiphallus, wrapping once around vas deferens but not attaching to it. Epiphallus longer than penis, internally with longitudinal pilasters. Epiphallic retractor caecum absent; Lime-sac present. Spermatophore long soft-walled tube closed at both ends, sculptured with two longitudinal ridges, one with a row of tiny teeth.   
 Radula (Figure 42J–L): Relatively long and narrow. Central tooth with small ectocones; mesocone lanceolate, similar in length to tooth base. Lateral and marginal tooth fields distinguishable. Lateral teeth with endocone much smaller than central tooth ectocones; ectocone equal in size to those on central tooth; mesocone slightly longer than tooth base. Marginal teeth with endocones absent; ectocones approximately same length and breadth as mesocone, not subdivided into extra teeth. Radular formula (43.10.1.10.43) × 91 rows.   
 Remarks. Baker (1941a) included a number of groups as subgenera within Orpiella, but stated that a proper revision could not take place without the study of more material. Schileyko (2002b) raised most of these subgenera to generic level, including Owaraha and Kalendyma, both of which are restricted to the Solomon Islands. In the current study, Baker’s (1941a) more conservative approach is followed.   
 The species dissected in the current study has strong similarities to the type species of Kalendyma, Orpiella (K.) compluviata (Cox, 1871), particularly in the form of the spermatophore with two ridges, one toothed and one smooth (Rensch & Rensch 1936). The other reproductive characters are also similar, as is the shell (Schileyko 2002b). However, the two species differ in the presence of a fine filiform keel on the shell of Orpiella (K.) compluviata and the presence of flat radial ribs on the shell of O. (K.) concavum.   
The varying taxonomic placement of this genus is outlined above (Family Trochomorphidae: Remarks).  
 In the phylogenetic analysis, Orpiella concavum was the sister taxon to Helicarionoidea and did not group with Trochomorphidae (Figures 1–3). However, in the molecular phylogenetic analysis of Hyman et al. (2007), O. concavum grouped with Videna planorbis (Trochomorphidae) (Figure 44A).
description: Published as part of Hyman, Isabel T. & Ponder, Winston F., 2010, A morphological phylogenetic analysis and generic revision of Australian Helicarionidae (Gastropoda: Pulmonata: Stylommatophora), and an assessment of the relationships of the family 2462, pp. 1-148 in Zootaxa 2462 (1) on page 121, DOI: 10.11646/zootaxa.2462.1.1, http://zenodo.org/record/5312710