Pseudamnicola araujoi Delicado, Khalloufi & Hauffe, 2025

Pseudamnicola araujoi Delicado, Khalloufi & Hauffe sp. nov.

( Figs 5 View Figure 5 , 6 View Figure 6 )

ZooBank registration: urn:lsid:zoobank.org:act:D1CEB40E-0C7F-4FC1-A5D0-991A3CCF0B4A

Etymology

Named after Dr Rafael Araujo, curator of Malacology at Museo Nacional de Ciencias Naturales (MNCN-CSIC) (2008–2021), who contributed greatly to the knowledge of freshwater molluscs, including those of Tunisia.

Type material

Holotype ( MNCN 15.05 About MNCN /200505H) and three paratypes ( MNCN 15.05 About MNCN /200505P) in the MNCN collection and 20 paratypes in the UGSB collection ( UGSB 17299 ). Type locality: Gnaa Spring , Jendouba, Tunisia.

Material studied

Gnaa Spring , Jendouba, Tunisia, 36.5653°N, 8.7895°E, leg. N.K., August 2015, MNCN 15.05 About MNCN /200505 and UGSB 17299 (80% ethanol) GoogleMaps .

Diagnosis

Shell small, ovate-conic; protoconch microsculpture pitted; central radular tooth formula 4-C-4/1-1; bursa copulatrix large, pyriform, with a duct longer than bursal length; SR1 long, 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 darkly pigmented, elongate (mean RPG ratio =.60).

Description

Shell ovate-conic, whorls 4–4.5, height 2.5–3 mm ( Fig. 5A–C View Figure 5 ; Supporting Information, Table S3). Periostracum yellowish. Protoconch ~450 µm wide, whorls 1.5; nucleus ~150 µm wide; protoconch microsculpture pitted ( Fig. 5G View Figure 5 ). 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 ( Fig. 5B View Figure 5 ). Umbilicus narrow, not covered by the inner lip. Holotype: SL = 2.87 mm, SW = 2.08 mm, AL = 1.61 mm, AW = 1.10 mm.

Operculum oval, yellowish, about two and a half whorls; muscle attachment area oval and located near the nucleus ( Fig. 5E, F View Figure 5 ).

Radular length intermediate, ~650 µm (~25% of total shell length), with ~55 rows of teeth ( Fig. 5H View Figure 5 ). Central tooth formula 4-C-4/1-1 ( Fig. 5I View Figure 5 ); basal tongue V-shaped, length about equal to lateral margin. Lateral tooth formula 3-C-3. Inner marginal teeth having ~20 tapered cusps, shortening towards the base. Outer marginal teeth with ~25 sharp cusps ( Fig. 5J View Figure 5 ).

Animal darkly pigmented, except for neck and tentacles ( Fig. 6F, G View Figure 6 ). 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. 6A View Figure 6 ). 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. 6B View Figure 6 ; Supporting Information, Table S4). Nervous system elongate (mean RPG ratio =.60), darkly pigmented, darker on ganglia than on connectives and commissures; cerebral ganglia approximately equal in size ( Fig. 6C View Figure 6 ).

Female glandular oviduct approximately three times as long as wide. Albumen gland shorter than capsule gland. Bursa copulatrix large, pyriform, almost as long as wide. Bursal duct longer than bursal length. Renal oviduct black-pigmented until the insertion of seminal receptacle, making one or two loops. Seminal receptacle elongate, with a short duct, joining renal oviduct at the insertion point with bursal duct ( Fig. 6D, E View Figure 6 ; 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. 6H View Figure 6 ). 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. 6F, G View Figure 6 ; Supporting Information, Table S6); base medium wide; attached well behind the right eye; penial duct narrow, curved, coursing close to outer edge.

Habitat

Endemic to a small spring, in which the species lives in high abundance. The substrate is composed of silt and gravel. The average water temperature varies between 14°C in winter and 25°C in summer. The conductivity varies between 0.53 and 0.78 mS. Co-occurring mollusc species are Bullaregia tunisiensis Khalloufi, Béjaoui & Delicado, 2017 , Pisidium sp. , Galba truncatula (O. F. Müller, 1774) , and Physella acuta (Draparnaud, 1805) .

Remarks

According to our DNA analyses, this species is more closely related to its congeners distributed in north-western Africa ( Morocco) than those distributed in north-eastern Africa ( Tunisia). It resembles Pseudamnicola conovula from Tunisia in shell and penis features (Supporting Information, Figs S7F–L, S View Figure 7 8O–Q View Figure 8 ). Otherwise, it differs in having a larger bursa copulatrix and a COI average sequence divergence of 7.4%. The shell and aperture shapes of P. araujoi are more similar to those of P. calamensis and P. linae (most probably a synonym of P. calamensis ) than any of the 15 Pseudamnicola species described in Algeria ( Glöer et al. 2010: figs 6–20), which are mostly known from their shells. The morphology and morphometry of its female genitalia are, however, different from the other two species ( Glöer et al. 2010: figs 6–20, for comparison; Fig. 2 View Figure 2 ).