Pseudamnicola sardiniensis Delicado, Boulaassafer & Hauffe, 2025

Delicado, Diana, Boulaassafer, Khadija, Khalloufi, Noureddine & Hauffe, Torsten, 2025, A holistic perspective on species delimitation outperforms all methods based on single data types in freshwater gastropods (Caenogastropoda: Hydrobiidae: Pseudamnicola), Zoological Journal of the Linnean Society 203 (1), pp. 1-31 : 26-27

Pseudamnicola sardiniensis Delicado, Boulaassafer & Hauffe sp. nov.

( Figs 15 , 16 )

Pseudamnicola sp. 7 — Delicado et al. 2018

Pseudamnicola sp. 7 — Boulaassafer et al. 2020

ZooBank registration: urn:lsid:zoobank.org:act:6A58528E-3FD4-4AC3-8BAC-589039156CFD

Etymology

The species name refers to the occurrence of this species on the island of Sardinia.

Type material

Holotype ( MNCN 15.05 /200504H) and three paratypes in the UGSB collection ( UGSB 15501 ). Type locality: stream near Bau sa Mela, Nurallao, Sardinia, Italy .

Material studied

Stream near Bau sa Mela, Nurallao, Sardinia, Italy, 39.8400°N, 9.1052°E, leg. M.S., September 2000, MNCN 15.05 /200504 and UGSB 15501 (80% ethanol) .

Diagnosis

Shell small, ovate-conic, with a short spire; protoconch microsculpture pitted; central radular tooth formula (5)4-C-4(5)/1-1; penis gradually tapering, with many folds over the entire surface, a moderately wide base and a small patch of pigmentation on its distal region; nervous system darkly pigmented, elongate (mean RPG ratio =.64).

Description

Shell ovate-conic, whorls 4, height 2.0– 2.5 mm ( Fig. 15A, B ; Supporting Information, Table S6). Periostracum yellowish. Protoconch ~400 µm wide, whorls 1.5; nucleus ~150 µm wide; protoconch microsculpture pitted ( Fig. 15C ). Teleoconch whorls moderately convex, with deep sutures; body whorl large, occupying about three-quarters of total shell length. Aperture longer than wide, slightly oval; inner lip thicker than outer lip; peristome margin simple, straight. Umbilicus narrow, not covered by the inner lip. Holotype: SL = 2.29 mm, SW = 1.75 mm, AL = 1.34 mm, and AW = 1.03 mm.

Operculum oval, yellowish, about two and a half whorls; muscle attachment area oval and located near the nucleus.

Radular length intermediate, ~500 µm (~25% of total shell length), with ~45 rows of teeth ( Fig.15D ). Central tooth formula (5)4-C-4(5)/1-1 ( Fig. 15E ); basal tongue V-shaped, length about equal to lateral margin. Lateral tooth formula 4-C-4. Inner marginal teeth having 20–25 tapered cusps, shortening towards the base. Outer marginal teeth with ~25 sharp cusps ( Fig. 15F ).

Animal darkly pigmented, except for neck and tentacles ( Fig. 16D ). Snout as long as wide, with medium distal lobation; foot size intermediate, with dorsal pigmentation. Ctenidium with ~15 well-developed gill filaments, occupying ~50% of pallial cavity length and posteriorly positioned. Osphradium of intermediate width and opposite middle of ctenidium ( Fig. 16A ). Stomach slightly longer than wide, with two chambers almost equal in size and a medium-sized posterior caecum; style sac longer than wide, surrounded by an unpigmented intestine ( Fig. 16B ; Supporting Information, Table S4). Nervous system elongate (mean RPG ratio =.64), darkly pigmented, darker on ganglia than on connectives and commissures; cerebral ganglia approximately equal in size ( Fig. 16C ).

Female genitalia unknown.

Male genitalia with a prostate gland approximately twice longer than wide, bean-shaped; seminal duct entering the middle-posterior region; pallial vas deferens emerging close to its anterior edge ( Fig. 16F ). Penis as long as head, gradually tapering, with many folds over the entire surface and a small patch of pigmentation on its distal region ( Fig. 16D, E ; Supporting Information, Table S6); base moderately wide; attachment area central; penial duct narrow, curved, coursing close to outer edge.

Habitat

Endemic to a small stream, where the species was found in low abundance.

Remarks

We dissected three of the eight specimens of P. sardiniensis deposited in the UGSB collection and found no female specimens. The shell of this species has a lower spire than that of the other two newly discovered species in Sardinia ( Pseudamnicola sp. 10 and 11). Its penis is slightly narrower than in the other two species. There is, however, a large genetic divergence (7.5% for COI) between P. sardiniensis and the other two species endemic to Sardinia ( Pseudamnicola sp. 10 and 11). The average sequence divergence with P. moussonii , another species of Pseudamnicola reported from the island ( Giusti and Castagnolo 1983), was 8% for COI.

Figures

Figure 15. Shells, operculum, and radulae of Pseudamnicola sardiniensis. A, holotype (MNCN 15.05/200504H). B–F, paratypes (UGSB 15501). A, B, shell.C, protoconch.D, portion of radula ribbon.E, central radular teeth. F, inner and outer marginal teeth.

Figure 16. Anatomy of Pseudamnicola sardiniensis. A–F, paratypes (UGSB 15501). A, ctenidium and osphradium.B, stomach. C, partial nervous system. D, head of male and penis. E, penis.F, prostate gland.