Iberozospeum costulatum Prieto and Jochum, n. sp., 2022

Kneubühler, Jeannette, Jochum, Adrienne, Prieto, Carlos E. & Neubert, Eike, 2022, Molecular investigation and description of Iberozospeum n. gen., including the description of one new species (Eupulmonata, Ellobioidea, Carychiidae), Organisms Diversity & Evolution 22 (1), pp. 61-92 : 87-89

Iberozospeum costulatum Prieto and Jochum, n. sp.

Type locality Mina del Pedreo (Bizkaia: Arcentales; 43.26800 -3.21402, 440 m).

Holotype A shell of 1.43 mm [ MNCN 15.05 /200128, ex. ZUPV 1952 ]; 22.02.2014, C. Prieto, A. Calvo, P. Jiménez leg.

Paratypes Mina del Pedreo [type locality]; 22.02.2014, C. Prieto, A. Calvo, P. Jiménez leg. [ ZUPV 1952 : 2 shells % 2 juvenile shells] 31.08.2014, C. Prieto, A. Calvo leg. [ ZUPV 2578 : 15 shells % 3 juvenile shells, ZUPV 2583 : 1 shell] [ MNCN 15.05 /200129: 5 shells]. Cueva de Valdebeci ( Bizkaia : Sopuerta : Beci ; 43.24516 -3.17316, 188 m); 20.10.2015, A. Calvo leg. [ ZUPV 3078 : 6 shells] [ NMBE 557231 : 1 specimen, sequenced; Fig. 11c ]. Cueva de Cuvias Negras (Cantabria: Soba: Asón; 43.25132 -3.60688, 250 m); 12.04.2017, C. Prieto, S. Quiñonero, A. Alonso, J. Ruiz-Cobo leg. [ ZUPV 4714 : 38 shells % 2 specimens] [ NMBE 557227 : 1 specimen, sequenced; Fig. 11b ; NMBE 568196 : 5 shells] [ SMF 349,424 : 5 shells] [ MHNG-MOLL-0137391 : 5 shells] [ MNCN 15.05 /200130: 10 shells] [ CAA ·w/o nº: 19 shells] [ CSQS ·w/o nº: 25 shells] .

Other material Cueva del Cesáreo (Cantabria: Liérganes: Extremera; 43.32034 -3.72279, 258 m); 21.03.2016, S. Quiñonero, J. Ruiz-Cobo, A. Alonso leg. [ ZUPV 3807 : 3 shells] [ CAA ·w/o nº: 1 shell] [ NMBE 559626 : 2 specimens, sequenced; Fig. 11a ]. Cueva de Asunción (Cantabria: Ramales de la Victoria: Guardamino ; 43.25837 -3.44820, 180 m); 21.03.2016, S. Quiñonero, J. Ruiz-Cobo leg. [ ZUPV 3808 : 4 shells]. Cueva del Comellante (Cantabria: Ruesga ; 43.31111 -3.60806, 170 m); 30.03.2015, S. Quiñonero, J. Ruiz-Cobo leg [ ZUPV 3804 : 1 shell] [ CSQS ·w/o nº:3 shells]. Cueva de Covallarco (Cantabria: San Roque de Riomiera : Merilla ; 43.25654 -3.73412, 402 m); 18.06.2016, CP, J. Fernández leg. [ ZUPV 3974 : 1 shell]. Cueva de Cullalvera (Cantabria: Ramales de la Victoria; 43.25577 -3.45808, 95 m); 19.09.2014, C. Prieto, A. Calvo leg. [ ZUPV 2604 : 1 shell]. Torca de El Porrón (Cantabria: Ruesga : Porracolina ; 43.25111 -3.66356, 920 m); 09.09.2016, M. Gutiérrez leg. [ ZUPV 4180 : 1 shell]. Cueva de La Puntida (Cantabria: Miera : Ajanedo ; 43.25883 -3.71042, 500 m); 12.10.2015, C. Prieto, A. Calvo leg. [ ZUPV 3032 : 90 shells] [ CSQS ·w/o nº: 10 shells]. Fuente de La Revilla (Cantabria: Voto : San Miguel de Aras ; 43.31972 -3.52036, 55 m); 30.03.2015, S. Quiñonero leg. [ ZUPV 3806 : 3 shells]. Cueva de Las Cascajosas (Cantabria: San Roque de Riomiera ; 43.25457 -3.71924, 328 m); 09.03.2018, C. Prieto, J. Ruiz-Cobo leg. [ ZUPV 5154 : 2 shells]. Cueva del Molino de la Peña (Cantabria: Rasines; 43.29101 -3.36840, 180 m); 04.08.2013, S. Quiñonero, J. Ruiz-Cobo leg. [ ZUPV 3802 : 2 shells, broken]. Sima PO-153 (Cantabria: San Roque de Riomiera : Porracolina; 43.22984 -3.69050, 585 m); 08.10.2016, M. Gutiérrez leg. [ ZUPV 4184 : 4 shells]; 12.11.2016, C. Prieto, M. Gutiérrez, J. A. Noriega leg. [ ZUPV 4203 : 20 shells]. Sima PO-27 (Cantabria: Miera; 43.24695 -3.67023, 910 m); 07.05.2016, M. Gutiérrez leg. [ ZUPV 3822 : 8 shells]. Cueva de San Juan de Socueva (Cantabria: Arredondo: Socueva; 43.26671 -3.61339, 430 m); 12.04.2017, C. Prieto, S. Quiñonero, A. Alonso, J. Ruiz-Cobo leg. [ ZUPV 4722 : 12 shells] .

Etymology The specific epithet derives from the well-defined ribbing of the last whorls of the shell.

Diagnosis A medium-sized (average, 1.35 mm, n = 52) and wide (average, 0.76 mm, n = 52) Iberozospeum species with convex whorls bearing well-defined ribs, oblique, reniform aperture with broad straight-edged parietal callus and a strong columellar lamella clearly seen inside the aperture.

Description ( Fig. 17 ). Shell of medium size (1.24–1.55 mm, n = 52, holotype, 1.43 mm), ovate conical. Spire formed by five (4.6–5.9, n = 52) rather convex whorls separated by a deep suture. Protoconch (nucleus, 0.175 mm wide) and apical whorls smooth ( Fig. 17f ) with teleoconch bearing regularly spaced (5–6/ 0.5 mm; 27 in the body whorl, n = 52), well-defined ribs, extending from one whorl to the next; ribs of the hind peristome region are more densely aligned and thinner. Body whorl large (holotype, 60% of the shell height), with upper convexity, ascending behind the aperture. Umbilicus closed, with ribs reaching the umbilical cavity. Aperture reniform, obliquely transverse (holotype, 47% of the shell height), attached to the body whorl by a thickly callused, broad, straight-edged parietal callus. Peristome wide and reflexed; lateral and palatal side regularly arched; columellar side almost straight and vertical. Inner lamella singular, large, oblique, ( Fig. 17g ) located above the parieto-columellar junction; lamella visible in oblique apertural view ( Fig. 17c ). Shell surface with micro sculpture of irregular spiral striae.

Geographical distribution Iberozospeum costulatum n. sp. inhabits caves throughout western Bizkaia and the eastern part of Cantabria ( Fig. 18 ). In Bizkaia, I. costulatum is known from two caves located 4.2 km apart: Mina del Pedreo, where it was first discovered, and Cueva de Valdebeci (holotype, sequenced population). Both caves belong to the same limestone formation (Alén-Lujar) cut by the Barbadun river. The remaining localities are in Cantabria. They are separated from the Bizkaian caves by a distance of 20 km, with Cueva Cullalvera and Cueva de Asunción being the nearest. All Cantabrian localities are located in the limestone massifs belonging to the Miera and Asón river basins with Cueva del Cesáreo (sequenced, Fig. 11a ) constituting the most north-western cave separated from this central block. We remark that I. costulatum appears to be sympatric with I. biscaiense in the Montes de Triano massif west of Bilbao (Prieto & Calvo 2013; unpublished records) and that the east-westward geographic span recorded for I. costulatum likely represents the true geographic distribution of this species.

Variability Ribbing is the most conspicuous feature on the shell of I. costulatum . Although the shells from the same cave show similar rib strength, spacing and length, a notable spectrum of variability is present in different cave populations. Shells deriving from populations from the Miera upper basin, such as La Puntida, PO-153 or Cuvias Negras ( Fig. 17j–k ), show poorly developed ribs and a weak columellar lamella, while individuals from Fuente de La Revilla bear strong and irregular ribs. On the other hand, shells from Asunción have well separated ribs (5/ 0.5 mm). Although obscured by wide intra-populational variation, shell size also varies between populations. Shells from Cuvias Negras are the smallest and those from Valdebeci are the largest. The inner columellar lamella also varies somewhat in form in shells from Cueva de Cesáreo, whereby in addition to the columellar lamella, a small basal lamella can be seen from the opening in oblique view ( Fig. 17h–i ).

Remarks The conspicuous ribbing differentiates I. costulatum from all other iberozospeid taxa except I. percostulatum . The shell of I. percostulatum is higher (1.34–1.80 mm, average 1.55 mm) and narrower (1.32–1.65 mm, average 1.51 mm, n = 42) and lacks inner lamellae ( Alonso et al., 2018). Additionally, their geographic ranges are 80 km apart.

Figures

Fig. 11 Iberozospeum costulatum. Yellow clade; (a) NMBE 559626, Cantabria, Lierganes, Cesareo, 21.3.2016, sh: 1.42 mm; (b) NMBE 557227, Cantabria, Ason, Soba, Cuvias Negras, 12.4.2017, sh 1.27 mm; (c) NMBE 557231, Alen, Sopuerta, Valdebeci, 20.10.2015, sh: 1.27 mm. — All phot.×40

◂Fig. 17 Iberozospeum costulatum n. sp. (a–e) holotype, 1.43 mm height [MNCN 15.05/200128, ex. ZUPV 1952], Mina del Pedreo (Bizkaia: Arcentales; 43.26800 -3.21402, 440 m). (f–g) paratype shells from the type locality [ZUPV 1952, F: juvenile shell, G: shell of 1.51 mm height. (h–i) no paratype shell of 1.48 mm height [ZUPV 3807] from Cueva del Cesáreo (Cantabria: Liérganes: Extremera; 43.32034 -3.72279, 258 m). (j–k) paratype shells from Cueva de Cuvias Negras (Cantabria: Soba: Asón; 43.25132 -3.60688, 250 m) [CSQS·w/o nº]. (l) no paratype shell from Cueva del Cesáreo [CSQS·w/o nº]. Photos a–i by Carlos Prieto; j–l by Sergio Quiñonero and Álvaro Alonso

Fig. 18 Geographical distribution of Iberozospeum costulatum n. sp. The type locality and sequenced populations are indicated by T and S, respectively