Bullaregia tunisiensis, Khalloufi & Béjaoui & Delicado, 2017

Khalloufi, Noureddine, Béjaoui, Mustapha & Delicado, Diana, 2017, A new genus and species of uncertain phylogenetic position within the family Hydrobiidae (Caenogastropoda, Truncatelloidea) discovered in Tunisian springs, European Journal of Taxonomy 328, pp. 1-15 : 6-10

Bullaregia tunisiensis sp. nov.

urn:lsid:zoobank.org:act:BDCEEEDE-8926-4D4C-93B0-9DE6AF75A7DF

Figs 3–5

Diagnosis

Shell 1.8 to 2.1 mm high, yellowish; central radular tooth formula 6–C–6/1–1; ovoid bursa copulatrix, with a duct longer than bursa; two seminal receptacles, SR1 elongate and pedunculate, SR2 globular

and sessile; prostate gland about 0.45 mm ovate in section, penis strap-like, with a dorsal, strap-like glandular lobe, and distal end tapered and greyish pigmented.

Etymology

The species epithet tunisiensis is an adjectival toponym that refers to Tunisia, where the species was found.

Type material

Holotype

TUNISIA: collected in Aïn Gnaa spring, Province Jendouba, 9 May 2008, leg. Khalloufi ( MNCN 15.05/60177H ).

Paratypes

TUNISIA: Aïn Gnaa spring, 10 ex., 9 May 2008, leg. Khalloufi ( MNCN 15.05/60177P); spring in Djebba, 15 Jun. 2009, leg Khalloufi ( MNCN 15.05/60178).

Type locality

TUNISIA: Aïn Gnaa spring (Bulla-régia), Province Jendouba, 36.5583 N, 8.74667 E, Alt. 206 m a.s.l.

Other material examined

TUNISIA: 56 ex. in ethanol 95% (30 dissected), province of Jendouba, Aïn Gnaa spring (Bulla-régia), 36.5583 N, 8.74667 E, 206 m a.s.l., 9 May 2008; 15 ex. in ethanol 95% (10 dissected), province of Jendouba, spring in Djebba, 36.47125 N, 9.0997223 E, 342 m a.s.l., 2 Feb. 2009; 45 ex. in ethanol 95% (35 dissected), province of Béja, 15 Jun. 2009.

Description

MEASUREMENTS. Holotype: H = 1.85 mm, W = 1.06 mm, AH = 0.73 mm, AW = 0.79 mm

SHELL. Ovate-conic, brown-yellowish, with 4–4.5 whorls ( Fig. 3A ); mean SH 1.6 mm ± 0.35 mm and SW 0.91 ± 0.15 mm; maximum height is 2.1 mm; mean SL / SW 1.75 ± 0.2; body whorl about ⅔ total length; rest of whorls slightly convex with deep sutures; aperture about 45% of shell height, complete, pyriform, slightly angled at the top and attached to body whorl; thin inner peristome but thicker than outer lip; peristome margin straight; umbilicus narrow.

OPERCULUM. With ca 2 whorls ( Fig. 3B ) and muscle attachment area oval and located near the nucleus.

RADULA. Intermediate length (20% total maximum shell length), bearing about 80 rows of teeth; central tooth formula 6–C–6/1–1 ( Fig. 4 A–B); lateral teeth formula 5–C–5; inner marginal teeth having 30–35 sharp cusps; outer marginal teeth having 25–30 sharp cusps ( Fig. 4C ).

PIGMENTATION AND ANATOMY. Visceral coil yellowish, showing by transparency the gonad; traces of pigment on pallial roof, visceral coil, anterior edge of mantle, foot and light pigment between tentacles ( Fig. 3D ). Black eyes surrounded by brownish pigment. Snout with medium distal lobation. Tentacles parallel-side, distal end nonexpanded. Ctenidium with 9–13 gill filaments; osphradium whitish, elongate, two times longer than wide and approximate opposite middle of ctenidium. Stomach with large gastric (posterior) caecum.

MALE GENTIALIA. Penis strap-like with a well-developed glandular lobe on the outer edge, 33% total penis length; glandular lobe strap-like and with a short duct; distal end of penis tapered, dark pigmented ( Figs 3C , 5A ). The penis has distinct basal and distal portions. The distal portion is smooth, with tapered end and variable in length. The basal portion is cylindrical and folded. Prostate gland, close, bean-shaped in outline, oval in section, and about twice as long as wide (0.45 mm / 0.25 mm). Posterior vas deferens forms the seminal vesicle with many loops. It is well-developed (about 4 mm in length and 0.1 mm in section) and strongly undulating, coiling immediately after it emerges from the testis and extending over the posterior and middle part of the stomach. The pallial vas deferens is a straight and narrow tube unciliated, entering postero-ventral portion of gland and exiting from its anterior end.

FEMALE GENITALIA. Ovary simple with stalked lobes. Pallial oviduct bearing an ovoid bursa copulatrix with a duct longer than its length; unpigmented renal oviduct, with a pouch at the end of the coiled section; two seminal receptacles; SR1 elongate with a short duct, close to the insertion point of the

bursal duct to the renal oviduct; SR2 globular, less developed and sessile, positioned near antero-ventral edge of bursa ( Fig. 5B ).

Remarks

Populations of this species from the Aïn Gnaa and Djebba springs vary only scarcely in terms of morphology and anatomy. In specimens from the Aïn Gnaa spring, the shell is generally more slender and has deeper sutures and a sharper protoconch. The portion of the vas deferens, forming the seminal vesicle, is more coiled and more developed. Pigmentation in the Djebba spring specimens is more intense, especially in the mantle and distal portion of the penis. Individuals from these populations are conchologically differentiated from similar regional species, such as Pseudamnicola meluzzi Boeters, 1976 and P. conovula (Frauenfeld, 1863) , by their smaller and slender shell, a taller penultimate whorl relative to remaining whorls and by an aperture pyriform, angled on top.

Representatives of these two populations featured a similar shell morphology as the specimens from Algeria deposited in the Muséum national d’Histoire naturelle, Paris (MNHN). These specimens were earlier identified as Amnicola seminium ( Morelet, 1857) by Bourguignat. However, this species, illustrated by Morelet in the original description ( Morelet 1857, pl. XII fig. 10) differs from the Algerian specimens deposited in the MNHN. Based on Morelet’s illustration (1857: pl. XII Fig. 10), the type of A. seminium has a larger body whorl, a shorter penultimate whorl and a rounder aperture (resembling Pseudamnicola ) than the MNHN specimens. Thus, these Algerian snails could have been misidentified. Based on common shell features shared by these specimens and Bullaregia gen. nov., such as ovateconic shape, tall penultimate whorl, aperture angled on top and closed umbilicus, they could be assigned to this new genus.

Figures

Fig. 3. Bullaregia tunisiensis gen. et sp. nov. A. Shell (holotype). B. Operculum. C. Head and penis. D. Coiled body.

Fig. 4. Radula of Bullaregia tunisiensis gen. et sp. nov. from a spring in Djebba, Tunisia. A. Rows of teeth of the radula. B. Detail of central teeth. C. Detail of lateral and marginal teeth.

Fig. 5. Genitalia of Bullaregia tunisiensis gen. et sp. nov. A. Penis (paratype). B. Distal female genitalia. Abbreviations: bc = bursa copulatrix; ov = renal oviduct; SR = seminal receptacle. Scale bar 0.1 mm.