Microcystinae, Thiele, 1931

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, Zootaxa 2462 (1), pp. 1-148 : 111-112

Subfamily Microcystinae

Remarks. In our analyses Microcystinae is monophyletic only if Liardetia doliolum is excluded ( Figure 1 ). Baker (1938) noted similarities between the shell of Liardetia and Euconulinae and the radula of Liardetia and Kaliella (currently placed in Chronidae ; Hausdorf 1998). However, while there are some differences between L. doliolum and the other Microcystinae included in the current study (e.g., bursa copulatrix at the junction of the penis and vagina rather than the base of the penis; presence of an epiphallic caecum), the majority of the characters place this species in Microcystinae . When Durgella cf. hatchongi and Cystopelta n. sp. are excluded, L. doliolum is included in a monophyletic Microcystinae (data not shown).

Hausdorf (1998) gave the following synapomorphies for this group: bursa copulatrix male side, partial detachment of the prostate, ovoviviparous reproduction. These characters are also included in Schileyko’s (2002a) description of the group.

Several of the species included in Microcystinae in the current study were placed in subfamilies of Helicarionidae by Schileyko (2002b) (e.g., Roybellia in Geotrochinae, Melloconcha , Innesoconcha and Mathewsoconcha in Helicarioninae) based on shell data. This will be discussed further in future papers [Hyman & Ponder, unpublished data based on Hyman (2005)], where the Microcystinae of Lord Howe and Norfolk Islands will be described.

Based on our analyses, key characters defining Microcystinae are:

Shell rarely reduced. Mantle with no visible minor blood vessels. Genital system ovoviviparous; bursa copulatrix usually very short, inserted on penis; stimulator absent; epiphallic retractor caecum and flagellum absent in most taxa. Spermatophore small, peanut-shaped, soft-walled; attached to inner wall of penis.

Description. Shell present, rarely reduced, ranging in diameter from ~ 2.5 mm in Pittoconcha concinna Preston, 1913 to 20 mm in Mathewsoconcha phillipii ( Gray, 1834) . Shell shape and sculpture variable. Mantle laps absent, or only right lap present, or both laps present; mantle laps long and narrow in shape; not fused. Mantle lobes small. Sole of foot tripartite; caudal apparatus formed from curled up sole ( Muratov’s 1999 helicarionid type); caudal apparatus very small to moderately large; caudal foss horizontal slit in tail. Kidney unilobed; mantle with no visible minor blood vessels, pigmentation absent or present, mantle gland absent or present. Genital system ovoviviparous; oviduct non-glandular. Neither carrefour nor talon embedded in albumen gland. Post-uterine oviduct very long; capsular gland absent. Bursa copulatrix very short in most taxa; inserted on penis; duct of bursa copulatrix wide; not distinguishable from bursa copulatrix (in Liardetia doliolum bursa copulatrix is short, inserted at junction of penis and post-uterine oviduct and duct of bursa copulatrix is narrow, distinguishable from bursa copulatrix). Stimulator absent. Epiphallus enters penis through simple pore, rarely two fleshy lips or verge; penis internally with no sculpture, or with longitudinal ridges or longitudinal, circular or transverse pilasters. Penial sheath present, enclosing coiled penis and epiphallus; closed at distal end; penis retractor muscle attached to penis or to epiphallus near penis junction. Epiphallic retractor caecum absent (most taxa) or present ( Liardetia doliolum ); epiphallic flagellum absent. Spermatophore small, peanut-shaped, soft-walled; attached to inner wall of penis. Radula relatively long and narrow. Central tooth with small to moderately small ectocones; mesocone lanceolate. Lateral and marginal tooth fields distinguishable. Tooth rows straight.

Figures

FIGURE 1. Majority-rule consensus tree (1,743 trees, length 117 steps) from the morphological analysis containing representatives of all groups. Families and subfamilies are shaded and are labelled in bold if the group is not monophyletic.