Radomaniola dolens, Delicado & Hauffe, 2022

Delicado, Diana & Hauffe, Torsten, 2022, Shell features and anatomy of the springsnail genus Radomaniola (Caenogastropoda: Hydrobiidae) show a different pace and mode of evolution over five million years, Zoological Journal of the Linnean Society 196, pp. 393-441 : 415-418

RADOMANIOLA DOLENS SP. NOV.

( FIGS 12 , 13 )

Z o o b a n k r e g i s t r a t i o n: z o o b a n k. org:act: 1DCAC494-B7E4-47B4-B0E7-7701B39DF9A9

Etymology: The name dolens means painful in Latin and is derived from Achérōn, the Greek name of the Acheron River, or ‘River of Woe’ in Ancient Greek mythology, where the type locality of this species is located.

Type material: Holotype ( MNCN 15.05 /200159), five paratypes ( MNCN 15.05 /200160) in the MNCN collection and ~ 20 paratypes in the UGSB collection ( UGSB 16932 ). Type locality: Springs of the Acheron River, Glyki, Greece.

Material studied: Springs of the Acheron River, Glyki, Greece, 39.3280°N, 20.6235°E, M.B., August 2014, MNCN 15.05 /200160 and UGSB 16932 (80% ethanol). Diagnosis: Protoconch microsculpture wrinkled; central radular tooth formula 6-C-6/1-1; bursa copulatrix globular, duct longer than bursal length; SR1 elongate, duct short; SR2 elongate, smaller than SR1, duct short; penis unpigmented, gradually tapering, base narrow, shorter than head length; nervous system weakly pigmented, elongate (mean RPG ratio = 0.50) .

Description: Shell ovate-conic, 3.5–4.0 whorls, height 1.75–2.25 mm ( Fig. 12A–C ; Supporting Information, Table S6). Periostracum yellowish, sometimes whitish. Protoconch ~400 µm wide, 1.5 whorls; nucleus ~150 µm wide; protoconch microsculpture wrinkled ( Fig. 12G ). Teleoconch whorls convex, with deep sutures; body whorl large, occupying about two-thirds of total shell length. Aperture slightly oval; inner lip thicker than outer lip; peristome margin simple, straight ( Fig. 12B ). Umbilicus narrow, not covered by the inner lip. Operculum oval, brownish, about two whorls; muscle attachment area oval and located near the nucleus ( Fig. 12E, F ). Radular length intermediate, ~600 µm (~25% of total shell length), with ~60 rows of teeth ( Fig. 12H ). Central tooth formula 6-C-6/1-1 ( Fig. 12I ); basal tongue U-shaped, length about equal to lateral margin. Lateral tooth formula 5-C-5. Inner marginal teeth having 28–30 tapered cusps, shortening toward the base. Outer marginal teeth with 25–27 sharp cusps ( Fig. 12J ).

Animal darkly pigmented except for neck and tentacles ( Fig. 13F ). Ctenidium with 11–12 welldeveloped gill filaments, occupying ~50% of pallial cavity length and positioned posteriorly. Osphradium of intermediate width and opposite middle of ctenidium ( Fig. 13A ). Stomach slightly longer than wide, with two chambers almost equal in size; style sac longer than wide, surrounded by an unpigmented intestine ( Fig. 13B ; Supporting Information, Table S7). Nervous system slightly pigmented, elongate (mean RPG ratio = 0.50); cerebral ganglia approximately equal in size, presenting small black granules ( Fig. 13C ).

Female glandular oviduct approximately three times longer than wide. Albumen gland shorter than capsule gland. Bursa copulatrix globular, slightly longer than wide. Bursal duct longer than bursal length. Renal oviduct unpigmented, coiled. SR1 elongate, duct short, joining renal oviduct slightly above the insertion point with bursal duct. SR2 smaller than SR1, elongate, with a short duct, located on renal oviduct near loop ( Fig. 13D, E ; Supporting Information, Table S8).

Male genitalia with a prostate gland approximately two times longer than wide, bean shaped; seminal duct entering the middle-posterior region; pallial vas deferens emerging close to its anterior edge ( Fig. 13H ). Penis unpigmented, gradually tapering, shorter than head length, base narrow, weakly folded along inner edge and with one medial outgrowth on its left side ( Fig. 13F, G ; Supporting Information, Table S9); penis attached well behind the right eye; penial duct narrow, near outer edge, almost straight.

Habitat: Endemic to the large, cold spring of the Acheron River, in which the species lives in moderate abundance.

Remarks: Genetic divergence in the small sample (N = 3) of R. dolens was relatively large (~2% for COI), as was the variation in shell shape and shell aperture observed in some individuals ( Fig. 12A–D ). Differences in shell shape might have been driven by shell erosion. We found no remarkable anatomical differences in this population. This species is distinguished from the geographically proximate and conchologically similar population of R. haesitans from the Louros River according to its wider shell umbilicus, smaller bursa copulatrix and SR1, more slender penis, lower RPG ratio and an average sequence divergence of 6.6% for COI (Supporting Information, Tables S4, S8 and S9).

Figures

Figure 12. Shells, operculum and radulae of Radomaniola dolens sp. nov. A, B, holotype (MNCN 15.05/200159). C–J, paratypes (UGSB 16932). C, D, shells. E, F, operculum (E, inner side; F, outer side). G, protoconch. H, portion of radula ribbon. I, central radular teeth. J, outer marginal teeth.

Figure 13. Anatomy of Radomaniola dolens sp. nov. A–H, paratypes (UGSB 16932). A, ctenidium and osphradium. B, stomach. C, partial nervous system. D, pallial oviduct. E, bursa copulatrix and seminal receptacles. F, head of male and penis. G, penis. H, prostate gland.