Paladilhiopsis stellatus Grego & Hofman, 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 stellatus Grego & Hofman sp. nov. Figures 6A-P , 7B-D , 8 , 9

Note.

mOTU A (Fig. 5 ); localities 1 and 2; Fig. 6A-P ; GenBank numbers: COI: MW741724-MW741738; H3: MW776417-MW776423

Type locality.

Spring Zvezda, above left bank of Cetina River, Slime, Omiš district, Croatia (43°26'13"N, 16°44'26"E) (Fig. 2B , locality 2).

Holotype. Ethanol-fixed specimen (Fig. 6C ), interstitially in the gravel below the bottom of the spring; J. Grego, A. Falniowski, R. Ozimec, M. Olšavský, J. Olšavská leg.; 08 August 2020; NHMW113632.

Paratypes. Type locality; J. Grego, A. Falniowski, R. Ozimec, M. Olšavský, J. Olšavská leg.; 08 August 2020; ten ethanol-fixed paratypes in the collection of the Department of Malacology of Jagiellonian University, dry specimens: ZMUJ-M.2633-2642, HNHM/2 specimens, NHMW-MO 113627/2 specimens, SMF362990/2 specimens, PG/2 specimens, JG-F1628 /158 specimens.

Other material.

Studena spring, concrete well ca. 80 m from road at hillside, Slime , Omis district Croatia; 43°25'43"N, 16°51'59.74"E; J. Grego, A. Falniowski, R. Ozimec, M. Olšavský, J. Olšavská leg.; 08 August 2020; JG F1626/ 20 specimens (Fig. 2A , locality 1); Studena spring, stony catchment, left bank of Cetina River , Slime, Omiš district Croatia; 43°25'45.48"N, 16°51'59.57"E; J. Grego, A. Falniowski, R. Ozimec, M. Olšavský, J. Olšavská leg.; 08 August 2020; JG-F1621/3 fragmented specimens (ca. 80 m uphill from locality 1) .

Diagnosis.

Shell minute, elongate-conic (turriform), distinguishable from the geographically close Paladilhiopsis elongata ( Kuščer, 1933) from spring Jadro near Split (HR) by less sinuated lateral labral profile, more inflated and more prominent body whorls, and a more elongate pyramidal shape. From P. solida Kuščer, 1933 from Vrelo Buna in Blagaj (BiH) differs by its smaller less conical shell with less prominent body whorl and slightly sinuate lateral labral margin adapically preceding. Can be distinguished from P. pretneri Bole & Velkovrh, 1987 from Antunovići near Kozice, Makarska district (HR) by its longer, more elongate shell and proportionally smaller body whorl. The receptaculum seminis long and tubular in shape, similar to that of P. bosniaca (Clessin, 1910), and different from the bulbous one with a long duct as in P. grobeni Kuščer, 1928.

Description.

Shell (Fig. 6A-P ) up to 2.94 mm high and 1.02 mm broad, ovate-conic (turriform), white or whitish, translucent, thin-walled, consisted of ca. six whorls, growing slowly and regularly, and separated by moderately deep but sharply marked suture. Spire high and conic, apex narrow, body whorl height less than 0.5 of the shell height. Aperture small, prosocline, oval, or elongated oval in shape, peristome complete and thin, umbilicus slit-like. Shell surface smooth, glossy, with growth lines hardly visible.

Measurements of holotype and sequenced and illustrated shells presented in Table 4 . Shell variability slight, marked mostly in breadth: height proportion of the shell and the aperture (Fig. 6A-P ).

Radula (Fig. 7B-D ) taenioglossate, typical of Paladilhiopsis , with numerous, long, and cusps. Rhachis formula:

(5)4-1-4(5)1-1 or 4-1-41-1

Basal cusps widely triangular and massive, median cusp at the cutting edge 2 × longer than the adjacent ones, lateral tooth formula: 3 - 1 - 4, the largest cusp prominent, nearly 2 × longer than the adjacent ones, on the inner marginal tooth ca. 18 large cusps similar to the ones on the rhachis, ca. 20 smaller and more slender cusps on the outer marginal tooth.

Soft parts morphology and anatomy. Body white, with no pigment, with no eyes. Female reproductive organs (Fig. 8 ) typical of the genus Paladilhiopsis ( Hofman et al. 2018), with unpigmented, long, and narrow renal oviduct, large bursa copulatrix, although less elongated than in P. grobbeni , and with its duct (characteristically for Paladilhiopsis ) lying proximally, single small distal receptaculum seminis (in the position of rs1 after Radoman 1973), with the outlet to the oviduct close to the outlet of the duct of the bursa copulatrix, and shortened accessory gland complex. Long narrow loop of the renal oviduct and small short seminal receptacle are characteristic of the species. The simple penis (Fig. 9 ) typical of the genus, without any outgrowth, tapering, in the form of an elongated triangle.

Derivatio nominis.

The specific epithet Paladilhiopsis stellatus refers to stella, the Latin word for star for the name of the type locality, Zvezda Spring, zvezda which means star in Croatian.

Known distribution.

Besides the type locality (locality 2: Spring Zvezda, above left bank of Cetina, Croatia), found also at locality 1: Studena spring, left bank of Cetina River, Slime, Croatia, 43°25'45.48"N, 16°51'59.57"E.

Remarks.

Molecularly this mOTU is the sister clade of the mOTU B ( Paladilhiopsis gittenbergeri ), but genetic distance is high, 11.3% for COI 3.5% for H3.

Figures

Figure 2. Some of the sampled localities A Studena spring (loc. 1) B Spring Zvezda (loc. 2) C, D Vrelo " Lusac " (Gucina) (loc. 3) (photographs A, B M. Olsavsky C, D A. Osikowski).

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).

Figure 8. Renal and pallial section of the female reproductive organs of Paladilhiopsis stellatus X. Abbreviations: bc - bursa copulatrix, cbc - duct of bursa, ga - albuminoid gland, gn - nidamental gland, gp - gonoporus, ov - oviduct, ovl - loop of (renal) oviduct, rs - seminal receptacle (in the position of Radoman's (1983) rs 1 - distal seminal receptacle). Scale bar: 500 μm.

Figure 9. Penes of Paladilhiopsis stellatus. Scale bars: 200 μm.