Ariopelta variegata, Sirgel, 2012

Sirgel, W. F., 2012, A new species of Oopeltidae (Mollusca, Pulmonata, Arionoidea), with a revision of the subfamily Ariopeltinae and remarks on its affinities within the family and superfamily, African Invertebrates 53 (2), pp. 527-527 : 533-536

Ariopelta variegata sp. n.

Figs 6–9 , 11

Etymology: From Latin variegata , referring to the varying body colour and the small white speckles on the dorsal area of the body.

Diagnosis: Characters that separate the new species from A. capensis are provided in Table 1.

Description:

Average contracted length 30 mm, when moving freely 80 mm. Mucus orange-yellow. Weakly developed grooves radiate from mantle, transversely interconnected by even less marked grooves to form small, elongated tubercules between them. Colour over dorsal two-thirds of body wall varies from dark bluish to black with small white speckles sparsely distributed in this field ( Fig. 6 ). At times, this area appears dark brown or even greenish, presumably as a result of the effect of the yellow mucus exuded. Ventral third of body wall and sole of foot cream to white in colour. Upper tentacles pigmented, lower ones white. Shell thin and calcareous, conforming in shape to that described for subfamily.

Cerebral commissure about as long as lateral connectives, cerebral ganglia thus located dorsolaterally in circumpharyngeal nerve ring. Retractor muscles of tentacles have a common trunk originating at the posterior margin of the pallial organs. Muscles of left and right sides diverge more or less ventrally to centre of pallial complex. Pharyngeal retractor diverges from left tentacle retractor and then splits into two branches about halfway along its route to buccal mass ( Fig. 7 ). Origin of penis retractor at posterior edge of kidney, to the left of and clearly separated from tentacle retractor. Both aorta and rectum penetrate diaphragm between and close to origins of penis and tentacle retractor muscles. Aorta located directly to the right of penis retractor and rectum directly to the left of origin of tentacle retractors. Tentacle retractor on right side passes between penis and vagina.

Ovotestis large, located below posterior border of pallium and has shape of an orange segment. It extends dorso-ventrally in left side of body, with broad convex side exposed at surface of visceral mass. Its acini small and tightly packed in covering membrane. Basal part of each frequently consists of two or three lobes. Spermathecal duct short, enters vaginal bulb distally to its equator. When fully developed, a large globular vaginal bulb extends all the way from free oviduct to join genital atrium distally ( Fig. 8 ). Transversely orientated, ring-shaped lamellae that intrude into its lumen each supported by a core of connective tissue. (This is unlike the situation in Ariopelta capensis , where such cores consist of calcareous structures.) Genital atrium extremely short, hardly emerging above inner surface of body wall. Penis consists of three serially arranged parts. First part small and tubular; and it receives vas deferens at its proximal end. Distally, it passes into a

TABLE 1 Characters separating Ariopelta variegata sp. n. from Ariopelta capensis .

dilated second part. These two parts describe a hairpin loop ( Fig. 8 ). Third section also dilated but slightly smaller than second, from which it is delimited by a constriction. It passes directly into genital atrium. Wall of second part carries spine-shaped papillae that intrude into lumen, these being devoid of calcareous cores. The arrangement is a strip of long papillae on a thick part of wall adjacent to first part of penis, while papillae on remaining, thinner part of wall distinctly shorter, although still well developed ( Fig. 9 ). Inner surface of wall of third part of penis also bears spinous papillae but these are much smaller, almost imperceptible, and they only found in fully developed individuals. Penis retractor muscle inserts broadly on distal section of first part of penis, with a few strands being continued on to second part ( Fig. 8 ).

Holotype: SOUTH AFRICA: Western Cape: Kogelberg Nature Reserve , 34°17'13.89''S 18°52'58.48''E, 305 m, 19.x.1985, W.F. Sirgel ( NMSA 8602 / T2964 ).

Paratypes: 2 specimens, same data as holotype ( NMSA W8603 / T2965 , W8604/ T2966 ) ; 1 specimen, same locality as holotype, 31.viii.1985, W.F. Sirgel ( NMSA W8604 / T2966 , dissected) .

Other material examined (dissected) but not preserved: Same locality as holotype , 1 specimen collected 10.xii.1984, similar to holotype, 80 mm long when it moved freely ( Figs 7, 8 and 9 drawn from this specimen); 1 specimen collected 19.x.1985 (60 mm long); 2 specimens collected 31.viii.1985, 60 mm and 40 mm long, respectively ( Fig. 11 prepared from the latter (young) specimen).

Figures

Fig. 6. Ariopelta variegata sp. n., holotype in extended and in contracted conditions (composite image).

Figs 7–9. Ariopelta variegata sp. n.: (7) dorsal view to show arrangement of retractor muscles; (8) genital system.Abbreviations:ALB GL – albumengland,AO – position where aorta penetrates the diaphragm, GA – genital aperture, G ATR – genital atrium, L+R TR – left and right tentacle retractor muscles, L P – large papillae, OV – free oviduct, OVOT – ovotestis, PH R – pharynx retractor muscle, PR – penisretractor muscle,RECT – position where rectum penetrates the diaphragm,S P – small papillae, SPOV – spermoviduct, SPT – spermatheca, VAG B – vaginal bulb, Vd – vas deferens, VSP – very small papillae, 1–3 indicate the successive parts of the penis; (9) penis with second and third parts opened to show interior.

Figs 10, 11. (10) Amalia ponsonbyi, generative organs (after Collinge 1900; annotations changed to fit terminology in present paper); (11) Ariopelta variegata sp.n., genital system of juvenile.Abbreviations: AG – atrial gland, ALB GL – albumen gland, G ATR – genital atrium, OV – free oviduct, OVOT– ovotestis, PR – penis retractor, SPOV – spermoviduct, SPT – spermatheca, VAG B – vaginal bulb, Vd – vas deferens, 1–6 or 1–3 – successive parts of penis.