Pseudamnicola argentariensis 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 : 16-18

Pseudamnicola argentariensis Delicado, Boulaassafer & Hauffe sp. nov.

( Figs 7 , 8 )

Pseudamnicola sp. 1 — Delicado et al. 2018 Pseudamnicola sp. 1 — Boulaassafer et al. 2020

ZooBank registration: urn:lsid:zoobank.org:act:FBFFB25D-0A78-4EAF-A578-60EC1F6A761D

Etymology

Referring to Monte Argentario ( Italy), a municipality located near the type locality .

Type material

Holotype ( MNCN 15.05 /200500H; dissected animal) and four paratypes ( MNCN 15.05 /200500P) in the MNCN collection and ~ 50 paratypes in the UGSB collection ( UGSB 11999 ). Type locality: a spring below the Fontana Carpina , Monte Argentario, Grosseto Province, Italy.

Material studied

A spring below the Fontana Carpina , Monte Argentario, Grosseto Province, Italy, 42.4242°N, 11.0908°E, leg. S.C. and M.C., September 2012, MNCN 15.05 /200500 and UGSB 11999 (80% ethanol) .

Diagnosis

Shell relatively slender (SL/SW ratio> 1.5); protoconch microsculpture pitted; central radular tooth formula 4-C-4/1-1; bursa copulatrix large, pyriform, with a duct longer than bursal length; SR1 elongate, with a short duct; penis gradually tapering, with many folds over the entire surface and a small patch of pigmentation on its distal region; nervous system slightly pigmented, elongate (mean RPG ratio =.61).

Description

Shell ovate-conic, whorls 4–5, height 2.5–3.5 mm ( Fig. 7A–C ; Supporting Information, Table S3). Periostracum yellowish. Protoconch ~450 µm wide, whorls 1.5; nucleus ~125 µm wide; protoconch microsculpture pitted ( Fig. 7G ). Teleoconch whorls moderately 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. 7D ). Umbilicus narrow, not covered by the inner lip. Holotype: SL = 3.46 mm, SW = 2.01 mm, AL = 1.69 mm, and AW = 1.24 mm.

Operculum oval, brownish, about two and a half whorls; muscle attachment area oval and located near the nucleus ( Fig. 7E, F ).

Radular length intermediate, ~675 µm (~25% of total shell length), with ~65 rows of teeth ( Fig. 7H ). Central tooth formula 4-C-4/1-1 ( Fig. 7I ); basal tongue V-shaped, length about equal to lateral margin. Lateral tooth formula 3-C-3. Inner marginal teeth having 20–23 tapered cusps, shortening towards the base. Outer marginal teeth with ~25 sharp cusps ( Fig. 7J ).

Animal darkly pigmented, except for neck and tentacles ( Fig. 8F ). Snout as long as wide, with medium distal lobation; foot size intermediate, with dorsal pigmentation. Ctenidium with 17–19 well-developed gill filaments, occupying ~50% of pallial cavity length and posteriorly positioned. Osphradium of intermediate width and opposite middle of ctenidium ( Fig. 8A ). 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. 8B ; Supporting Information, Table S4). Nervous system elongate (mean RPG ratio =.61), slightly pigmented, darker on ganglia than on connectives and commissures; cerebral ganglia approximately equal in size ( Fig. 8C ).

Female glandular oviduct approximately four times longer than wide. Albumen gland shorter than capsule gland. Bursa copulatrix pyriform, slightly longer than wide. Bursal duct longer than bursal length. Renal oviduct black-pigmented until the area above the insertion of seminal receptacle, coiled. Seminal receptacle elongate, with a short duct, joining renal oviduct slightly above the insertion point with bursal duct ( Fig. 8D, E ; Supporting Information, Table S5).

Male genitalia with a prostate gland approximately twice as long as wide, bean-shaped; seminal duct entering the middle-posterior region; pallial vas deferens emerging close to its anterior edge ( Fig. 8H ). Penis almost as long as head, gradually tapering, with many folds over the entire surface and a small patch of pigmentation on its distal region ( Fig. 8F, G ; Supporting Information, Table S6); base moderately wide; attached well behind the right eye; penial duct narrow, curved, coursing close to outer edge.

Habitat

Endemic to a coastal spring on the Monte Argentario Peninsula.

Remarks

Two hydrobiid populations occurring in Monte Argentario at the Fonte delle tre Viti Spring and Romito Spring were identified as Amnicola moussoni ( Calcara 1841) (= Pseudamnicola moussonii ) and Amnicola vestita (Benoit, 1875) , respectively, by Paulucci (1886). Our studied population near Fontana Caprina is here considered a distinct species because: (i) the two cited species by Paulucci (1886) were originally described from Sicily, and our integrative evidence suggested that the Pseudamnicola species from Sicily have more restricted ranges than previously thought; (ii) according to Giusti (1976), A. vestita is a synonym of P. moussonii ; and (iii) there are clear genetic (6.2% average sequence divergence for COI) and morphological differences (e.g. in shell or female genitalia features) between P. argentariensis and P. moussonii . Manganelli et al. (2017) reported several Pseudamnicola populations in Monte Argentario, one from the same area as our studied snails, and tentatively classified them into P. moussonii . Based on our species delimitation results, we recommend further genetic verification of this species identification, because P. argentariensis can potentially occur in other localities in the region.

Pseudamnicola argentariensis is one of the few slender-shelled representatives of the genus. In comparison to other slender-shelled species, it can be distinguished by: its wider spire and larger aperture from Pseudamnicola luteolus (Küster 1852-1853) from Algeria ( Glöer et al. 2010: fig. 21); its smaller shell, larger aperture, less convex spire whorls, longer bursal duct, and wider penis from P. granjaensis from Majorca ( Delicado et al. 2014: figs 4, 8); and its more globous shell, wider spire, and larger aperture from Pseudamnicola sciaccaensis Glöer & Beckmann, 2007 from Sicily ( Glöer and Beckmann 2007: fig. 1).

Snails were found in high abundance at the type locality, with the great majority being juveniles. Adult shells differed from the ones of the closely related P. lucensis according to their generally higher spire and larger aperture (Supporting Information, Fig. S9 ). Pseudamnicola argentariensis differs anatomically by having a larger bursa copulatrix, more slender penis, longer radula, and fewer cusps on the lateral radular teeth ( Giusti 1976; Supporting Information, Fig. S10 ). Based on these morphological differences, previous studies identified these snails as a

18 • Delicado et al.

different species of Pseudamnicola , not belonging to P. lucensis , and referred to as Pseudamnicola sp. 1 ( Delicado et al. 2018, Boulaassafer et al. 2020).

Figures

Figure 7. Shells, operculum, and radulae of Pseudamnicola argentariensis. A, holotype (MNCN 15.05/200500H). B–J, paratypes (UGSB 11999). A–D, shells. E, F, operculum (E, inner side; F, outer side). G, protoconch. H, portion of radula ribbon. I, central radular teeth. J, inner and outer marginal teeth.

Figure 8. Anatomy of Pseudamnicola argentariensis. A–H, paratypes (UGSB 11999). A, ctenidium and osphradium. B, stomach. C, partial nervous system. D, pallial oviduct. E, bursa copulatrix and seminal receptacle.F, head of male and penis.G, penis.H, prostate gland.

Figure 9. Shells, operculum, and radulae of Pseudamnicola bodoni. A, holotype (MNCN 15.05/200502H). B, paratype (UGSB 988). C, shell (UGSB 5697). D, shell (UGSB 16628). E, F, operculum (E, inner side; F, outer side) (UGSB 988). G, protoconch (UGSB 988). H, portion of radula ribbon (UGSB 988). I, central radular teeth (UGSB 988). J, inner and outer marginal teeth (UGSB 988).

Figure 10.Anatomy of Pseudamnicola bodoni. A–H, paratypes (UGSB 988). A, ctenidium and osphradium. B, stomach. C, partial nervous system.D, pallial oviduct. E, bursa copulatrix and seminal receptacle.F, head of male and penis.G, penis. H, prostate gland.