Paladilhiopsis arion Rysiewska et Osikowski, 2021

Hofman, Sebastian, Grego, Jozef, Rysiewska, Aleksandra, Osikowski, Artur & Falniowski, Andrzej, 2021, Two new species of the Balkan genus Paladilhiopsis Pavlovic, 1913 (Caenogastropoda, Moitessieriidae), ZooKeys 1046, pp. 157-176 : 157

Paladilhiopsis arion Rysiewska et Osikowski sp. nov. Figures 6Q-S , 7A

Note.

mOTU C (Fig. 5 ); locality 3; Fig. 6Q-S ; GenBank numbers: COI: MW741739- MW741740; H3: MW776424-MW776425

Type locality.

Vrelo “Lušac” ( Gučina), BiH (42°42'04"N, 18°21'27"E) (locality 3).

Holotype. Ethanol-fixed specimen (Fig. 6Q ), interstitially (pumped with Bou-Rouch pump), in the gravel below the bottom of the spring; 10 Sept 2019; A. Falniowski, A. Rysiewska and A. Osikowski leg., voucher number: ZMUJ-M.2643.

Paratypes. Five empty shells, in the collection of the Department of Malacology of Jagiellonian University, voucher numbers: ZMUJ-M.2644-2648.

Diagnosis.

Shell minute, elongate-conic (turriform), with relatively narrow spire, whose breadth grows rapidly, acute narrow apex, and narrow but long aperture with prominent lip, distinguishable from the geographically close Paladilhiopsis matejkoi Grego & Glöer, 2019 from Nemila Spring, Herceg Novi (MNE) and P. montenegrinus ( Schütt, 1959, described as Saxurinator ) from Bileća (BiH) by its more conical shell shape with slightly pagoda-shaped whorls, sharper apex, and deeper suture. From P. matejkoi it can additionally be differentiated by its more declined aperture.

Description.

Shell (Fig. 6Q-S ) 2.51 mm high and 0.91 mm broad, elongate-conic (turriform), white, translucent, thin-walled, consisted of ca. six and half whorls, growing slowly and regularly in their height, but growing rapidly in breadth, separated by moderately deep but sharply marked suture. Spire high and slim, apex acute, body whorl height ca. 0.38 of the shell height. Aperture narrow but long, peristome complete, forming a prominent lip, umbilicus slit-like. Shell surface smooth, glossy, with clearly visible broad growth lines, forming ribs (Fig. 7A ).

Measurements of holotype and sequenced and illustrated shells provided in Table 4 .

Soft parts morphology and anatomy. The body is white, without pigment, with no eyes. The arrangement of pellets in the rectum characteristic for the Moitessieriidae ( Boeters and Gittenberger 1990). The anatomy is unknown.

Derivatio nominis.

The specific epithet Paladilhiopsis arion refers to the ancient name of River Trebišnjica, which in classical antiquity was known as the Arion, rising and sinking through its course before resurfacing at various places from the Neretva to the coast; Trebišnjica is adjacent to the type locality.

Known distribution.

Only the type locality.

Remarks.

Molecularly this mOTU is the sister clade of the mOTU D ( Paladilhiopsis matejkoi ), with genetic distances 5.9% for COI 1.6% for H3.

Figures

Figure 5. Maximum likelihood tree computed for concatenated partial sequences of COI and H 3 sequences. Bootstrap supports given if ≥ 60 %.

Figure 6. Shells of Paladilhiopsis A-P P. stellatus A, B locality 1, Studena spring (2 H 58, 2 H 59) C-P locality 2, Zvezda spring (holotype, 2 H 69, 2 H 60 - 2 H 61, 2 I 19 - 2 I 28, respectively) Q-S P. arion, locality 3, Vrelo " Lusac " (Gucina), BiH (holotype, 2 G 19, 2 G 22).

Figure 7. A teleoconch sculpture of Paladilhiopsis arion B-D radula of P. stellatus. Scale bars 50 μm (A); 10 μm (B-D).