Daphniola dione, Radea & Lampri & Bakolitsas & Parmakelis, 2021

Radea, Canella, Lampri, Paraskevi Niki, Bakolitsas, Konstantinos & Parmakelis, Aristeidis, 2021, A new hydrobiid species (Caenogastropoda, Truncatelloidea) from insular Greece, Zoosystematics and Evolution 97 (1), pp. 111-119 : 111

Daphniola dione sp. nov. Figs 3 , 4

Etymology.

The specific name (in apposition) derives from Greek mythology: Dione, (Διώνη in Greek), was the mother of the goddess Aphrodite according to the Greek poet Homer, author of Iliad and Odyssey.

Diagnosis.

Shell minute (maximum height 0.98 mm, maximum width 1.31 mm), valvatiform; soft body without any pigmentation; eyes small; penis long, narrow, tapered, with wider wrinkled proximal portion, filamentous distal portion and an obtuse outgrowth on the left side forming an acute angle with the penis distal portion; female genitalia with large pyriform bursa copulatrix, renal oviduct coiled in a equilateral triangle. Differentiated from D. exigua by its smaller size, wider and more open umbilicus, paler operculum, lack of pigmentation in soft body, pyriform-shaped bursa copulatrix, wider bursal duct, triangle-shaped oviduct and obtuse rather than pointed outgrowth at the distal penis portion. Differentiated from D. louisi by its smaller size, lack of pigmentation in soft body, large, pyriform and protruding bursa copulatrix, triangle-shaped oviduct, nearly centered penial duct, and more prominent penial outgrowth. Differentiated from D. eptalophos by its smaller size, paler operculum, lack of pigmentation in soft body, protruding bursa copulatrix, wider bursal duct, triangle-shaped oviduct, more pointed penial apex, outgrowth on distal rather than proximal penial portion and nearly centered penial duct. Differentiated from D. hadei by its larger size, wider and more open umbilicus, pyriform and protruding bursa copulatrix, more pointed penial apex and more prominent penial outgrowth. Differentiated from D. magdalenae by its smaller size, wider and more open umbilicus, paler operculum, protruding bursa copulatrix, more pointed penial apex and presence of eyes.

Type-locality.

Cave spring on Lefkada Island, Ionian Sea, Greece, 38.722532°N, 20.682713°E, 240 m a.s.l., 15.V.2017, K. Bakolitsas leg.

Type material.

Holotype. Ethanol-fixed specimen, GNHM 39587. Paratypes (from the same lot). Two ethanol-fixed specimens, GNHM 39588. Seven ethanol-fixed mature specimens dissected for anatomical study. Three mature and seven immature specimens are in the personal collection of C. Radea deposited in the Section of Ecology and Systematics, Department of Biology, NKUA.

Description.

Shell (Fig. 3A-L ). Valvatiform with up to 3.25 whorls, thin, colorless, transparent and crystalline when fresh, finely striated; spire more or less depressed; whorls rounded, regularly growing with shallow sutures. Measurements are given in Table 3 . Periostracum light cream-colored; aperture adhering to the last whorl, prosocline, roundish to ovate; peristome continuous, slightly thickened at columellar margin, the outer margin simple; umbilicus open, deep, wide so that the first whorls can be seen through it (Fig. 3B, F ).

Operculum (Fig. 3F ). Ovate, thin, pliable, corneous, paucispiral, yellowish darker at the nucleus, with weakly convex inner face without any peg, nucleus sub-central.

Soft body pigmentation (Fig. 3A-L ). Soft body totally unpigmented and visible under the transparent shell; snout longer than wide, parallel-sided with medium distal lobation; eye spots very small.

Nervous system. Cerebral ganglia of the same size, white-colored; supraoesophageal and suboesophageal ganglia of the same size, smaller than cerebral ganglia, white-colored; supraoesophageal connective longer than suboesophageal connective.

Ctenidium-Osphradium. Ctenidium with ca 8-12 lamellae. Osphradium of intermediate width, opposite approximate middle of ctenidium.

Digestive system. Radula very fragile, not investigated; stomach unpigmented. Style sac smaller than stomach, not protruding to the intestinal loop; rectum (Fig. 3I, J ) with V-shaped bend, in some specimens with irregular V-shaped bend. The V-shaped bend is narrower in males (Fig. 3J ) than in females (Fig. 3I ). Faecal pellets are longitudinally packed.

Male reproductive system (Fig. 4A, B ) Penis whitish, medium-sized, narrow, long, gradually tapering bearing an obtuse outgrowth on the left side forming an acute angle with the penis distal portion; distal portion filamentous and usually bent; proximal portion bent upon itself and wrinkled; base of penis of intermediate width, its attachment area behind the right eye; penial duct strongly undulating especially in the proximal penis portion, near outer edge positioned, penial opening terminal; prostate like an elongate bean.

Female reproductive system (Fig. 4C ). Albumen and capsule glands very small, total mean height 0.38 mm (three specimens); bursa copulatrix large-sized, pyriform, posteriorly positioned and fully protruding from the posterior end of the albumen gland with longitudinal orientation relative to albumen gland; bursal duct anterior, wide and longer than bursa length; coiled oviduct unpigmented, well-developed forming an equilateral triangle with a vertical, V-shaped primary loop; two seminal receptacles; distal seminal receptacle (rs1) very small, globular without duct; proximal seminal receptacle (rs2) larger than distal one and smaller than bursa copulatrix, pyriform, with very short duct and a pink pearly shine, lying over the renal oviduct and against bursa copulatrix; an egg capsule with a single egg was found inside the umbilicus of one specimen (Fig. 3K, L ).

Μorphometric data along with conchological and anatomical characters of the nominal Daphniola species are provided in Tables 4 and 5 , respectively.

Distribution and habitat.

So far, the distribution of Daphniola dione sp. nov., is restricted to the type locality. The live specimens of the new species were found crawling on the roots of woody plants reaching the bottom of the spring.

Figures

Figure 3. Shells of Daphniola dione sp. nov. A., E. Dorsal view; B., F., K. Ventral view; C., D., G., H., L. Lateral view; I., J. Shape of rectum in females and males respectively. Scale bar 1 mm.

Figure 4. A., B. Penis (dorsal aspect); C. Female genitalia. Abbreviations are given in the section of Materials and Methods. Scale bar 0.5 mm.