Stanisicarion Hyman & Ponder, 2010

Hyman, Isabel T. & Köhler, Frank, 2019, Phylogeny and systematic revision of the helicarionid semislugs of eastern Queensland (Stylommatophora, Helicarionidae), Contributions to Zoology 88 (4), pp. 351-451 : 439

Stanisicarion Hyman & Ponder, 2010

Stanisicarion Hyman & Ponder, 2010: 49 .

Type species Helixarion freycineti Férussac, 1821 (by original designation); masculine.

Macularion Stanisic, 2010 in Stanisic et al., 2010: 312.

Type species Vitrina aquila Cox, 1868 (by original designation); masculine.

Remarks

Stanisicarion , which is of masculine gender, was originally introduced for Helixarion freycineti Férussac, 1821 and Vitrina virens Pfeiffer, 1849 , both previously included in Fastosarion ( Hyman & Ponder, 2010) . These two nominal species are distinguished from the rest of Fastosarion by their pustulose penis interior, the presence of a penial verge, the presence of only a short penial tunica, a less reduced shell, and less developed or fused shell lobes and lappets ( Hyman & Ponder, 2010). In the same year, the genus Macularion was described for another former member of Fastosarion , Vitrina aquila Cox, 1868 , based on the more prominent spiral sculpture on its shell and the strongly textured body surface of the animal.

We show herein that Stanisicarion and Macularion are sister taxa, each containing just a single species. Together they represent Clade C in the mitochondrial phylogeny. They have less reduced shells with a higher whorl count than most moderate Qld semislugs, with strongly pustulose shell lappets (most easily visible in S. freycineti when the animal is at rest). The extent of the mantle lobes and shell lappets was difficult to compare, given the differing degrees of contraction present in preserved material; if there is a difference, it is very slight. The reproductive system had a vagina with deep internal pilasters (although pilasters were not always observed in the capsular gland) and where eggs could be observed, they always had deep spiralling grooves, in contrast to the smooth spherical eggs seen in Fastosarion . The epiphallic caecum was short and hooked with the penis retractor muscle attaching near its base, and the penis had primarily pustulose internal sculpture, a small, elongate verge partially fused to the penial wall, and a penial tunica that in most specimens covered around half of the penis. In addition, the two genera grouped closely in the phylogenetic tree.

The genus as delineated herein is consistent with Clade C in the mtDNA phylogenies ( figs. 1–3 ).

Differential diagnosis

External appearance: Shell medium-sized to large (14–20 mm), golden to greenish amber, glossy, ear-shaped, 3.5–4.4 whorls, subglobose with a low spire, last whorl large, whorls rounded. Protoconch and teleoconch with very fine spiral grooves.Mantle lobes and shell lappets moderately large, completely covering shell when extended, pustulose, spotted; slime network prominent; tail keeled towards tip; caudal horn moderately small.

Genitalia: Spermoviduct of 3–5 lobes, embedded in digestive gland. Talon and carrefour embedded in albumen gland. Spermoviduct folded in zig-zag pattern. Free oviduct with oval, orange-brown capsular gland; interior of free oviduct with deep longitudinal pilasters, interior of capsular gland with folds in the thickened, glandular walls. Vagina moderately short, internally with longitudinal pilasters. Bursa copulatrix long, with slender duct and oval to elongate sac, inserted on the vagina. Penis long, slender, internally pustulose with no pilasters. Penis tunica covering only distal half of penis, attached by muscle fibres to middle of epiphallus; epiphallus enters penis through a short, conical verge, partially fused to penial wall, tip free; epiphallus 2 longer than epiphallus 1; epiphallic caecum situated in middle of epiphallus, short to moderately short, curved, penis retractor muscle attached at or near base; long, slender epiphallic flagellum with axial filament present, coiled and twisted irregularly. Spermatophore a soft-walled capsule with hard, smooth tail-pipe; tail-pipe mostly smooth, towards terminal end sculptured with a single spiraling toothed ridge.

Figures

FIGURE 1 Best maximum likelihood tree based on analysis of the concatenated data set of fragments of the mitochondrial genes 16S and COI using IQ-TREE.Ambiguous alignment sites in 16S removed using MAFFT.Numbers on branches indicate nodal support based on 10,000 ultra-fast bootstrap repeats as well as by employing Shimodaira-Hasegawa’s (1999) approximate Likelihood Ratio Test (‘SH-aLRT’). Scale bar indicating 10% of modelled sequence divergence. Shells shown to scale.

FIGURE 2 Majority-rule consensus tree based on Bayesian analysis of the concatenated data set of fragments of the mitochondrial genes 16S and COI. Ambiguous alignment sites in 16S removed using MAFFT. Numbers on branches indicate posterior probabilities. Scale bar indicating 40% of modelled sequence divergence. Shells shown to scale.

FIGURE 3 Best maximum likelihood tree based on analysis of the concatenated data set of fragments of the mitochondrial genes 16S and COI using IQ-TREE,with reduced taxon sampling (including only the ingroup). Ambiguous alignment sites in 16S removed using Guidance2. Numbers on branches indicate nodal support based on 10,000 ultra-fast bootstrap repeats as well as by employing Shimodaira-Hasegawa’s (1999) approximate Likelihood Ratio Test (‘SH-aLRT’).Scale bar indicating 10% of modelled sequence divergence. Shells shown to scale.