Siciliaria tiberii alcamoensis Brandt, 1961

De Mattia, Willy, Reier, Susanne & Haring, Elisabeth, 2021, Morphological investigation of genital organs and first insights into the phylogeny of the genus Siciliaria Vest, 1867 as a basis for a taxonomic revision (Mollusca, Gastropoda, Clausiliidae), ZooKeys 1077, pp. 1-175 : 1

Siciliaria tiberii alcamoensis Brandt, 1961 comb. nov.

Figs 1.F, 25.3-25.5, 26.6-26.9, 29.4, 29.5

Siciliaria (Siciliaria) alcamoensis Brandt 1961: 9.

Siciliaria (Siciliaria) septemplicata alcamoensis - Manganelli et al. 1995: 25.

Siciliaria septemplicata hemmeni Beckmann 2004: 190.

Charpentieria (Siciliaria) septemplicata alcamoensis - Nordsieck 2007: 54.

Siciliaria septemplicata alcamoensis - Nordsieck 2013b: 10.

Examined specimens.

Italy, Sicily, Cinisi, Piano Margi, 670 m asl, 38°08'58.56"N, 13°09'25.83"E, [Lab ID 37_1, COI: MW758928, ITS2: MW757102, MW757101], W. De Mattia and J. Macor leg., 14.iv.2017. 2 dissected spm.

Shell

(Figs 26 .6-26.9, 29.4-29.5). Shell decollate; whorls striated to rib-striated; dorsal keel very prominent; inferior lamella high; anterior upper palatal plica present, mostly separated from upper palatal plica, sometimes a second or also third upper palatal plica present; anterior lower palatal plica strong; palatal edge of clausilium plate distally not receding, palatal edge distally more or less strongly bent upwards.

Measurements

(n = 18, decollate): shell height 21.5 ± 1.3, whorl width 5.2 ± 0.3, aperture height 4.6 ± 0.2, aperture width 3.4 ± 0.4.

External morphology of the genital organs

(Fig. 25 .3). The FO is longer than the V (FO/V range 1.4-1.6). The VD is thin along its whole course. The FDBC is as long as the BC+SDBC (DBC/BC+SDBC = 1.0). The BC+SDBC is spindle-like to cylindrical and longer than the V (BC+SDBC/V range 1.4-1.5), with no distinction between the SDBC and the BC. The apex is pointed. The D is longer than the V (D/V range 2.5-2.6) and longer that the BC+SDBC (D/BC+SDBC range 1.6-1.8), thinner than the BC+SDBC and with a pointed apex. The V is long, cylindrical and small in diameter. The A is large. The PC is much longer than the V (P+E/V range 2.4-2.6). The PR is long and thin. The ET is clearly visible. There is a clear distinction between P and E, there is a visible ER, and a proximal narrowing. The E is longer than the P (E/P range 2.0-2.1), gradually shrinking and turning into the VD.

Internal morphology of the genital organs

(Figs 25 .4-25.5). The A shows a set of irregular fleshy folds. The P presents two or three main large longitudinal pleats. These pleats are heavily transversely segmented, getting a comb-like shape. The fine structure of the wall is smooth.

The PP is large, elongated, and heavily wrinkled. The P-E transition presents one ER with both the PP and ELP originating from the ER. The epiphallar formula is: 1ER(PP+ELP). The E shows a set of three or four smooth longitudinal pleats. The V is almost completely smooth. The wall shows a fine granulation.

Ecology.

Siciliaria tiberii alcamoensis comb. nov. inhabits scattered isolated limestone boulders, and is hiding in rock cracks and crevices. After careful field research in a wide area around Piano Margi, the taxon revealed to be remarkably rare and scattered.

Distribution.

Siciliaria tiberii alcamoensis comb. nov. is known only from a small area of less than 1 km2 in the surrounding of the type locality: Piano Margi south of Cinisi on the Montagna Longa. Further field research is needed to define its actual distribution range.

Remarks.

Brandt (1961: 9) described Siciliaria (Siciliaria) alcamoensis based on material from the Senckenberg Museum (SMF163949), provided by Monterosato and labelled as Clausilia difficilis from "Alcamo in NW-Sizilien, ohne nähere Fundortangabe". Brandt (1961: 9) introduced the name Siciliaria alcamoensis as Clausilia difficilis sensu Monterosato [non Clausilia difficilis Retowski, 1889, currently Roseniella difficilis (Retowski, 1889)] is a nomen nudum. Brandt (1961: 10) stated that he was not able to find this species again during field collecting nearby Alcamo, but he also lists in the type material: "Paratypoide Coll. Brandt Cl. 2365/2 leg. Belluci". He did not provide the collecting site of the paratype material so its origin is unknown, but it is conceivable that their shell morphology matches with what he described as Siciliaria (Siciliaria) alcamoensis indeed. Undoubtedly, the locality indication provided by Monterosato on the original SMF label is wrong. Despite intensive field research (WDM) all over the Alcamo area and Bosco d’Alcamo /Monte Bonifato, no specimens/population was found that matches Brandt’s description of Siciliaria alcamoensis . Beckmann (2004: 190) described Siciliaria septemplicata hemmeni from Piano Margi (Cinisi, Palermo). Its description and the pictures ( Beckmann 2004: 189 and 190) match with Brandt’s Siciliaria (Siciliaria) alcamoensis , as stated by Nordsieck (2013b: 7) and therefore, it is reasonable to assume that the Monterosato material (SMF163949) was collected from the same area of Beckmann’s species.

Siciliaria tiberii alcamoensis comb. nov. (Figs 26 .6-26.9) was treated as a subspecies of S. septemplicata (MolluscaBase 2021). This is due to the fact that the typical form of S. septemplicata (e.g., Monte Gallo populations, Figs 10 .1-10.7), is quite similar regarding the morphology of the clausiliar apparatus, ( Nordsieck 2013b), despite they greatly differ in the shell surface, sutures ornamentation, colouration, thickness and dimensions. The genital morphology (Figs 25 .3-25.4) of S. tiberii alcamoensis gretaly differs from that of S. s. septemplicata (Figs 9 .1-9.2). In the COI and concatenated trees, S. t. alcamoensis is is well embedded within the Siciliaria tiberii clade. Since it is found well within the distribution range of S. tiberii s. l., introgression due to hybridisation appears as an unlikely explanation. It might be better explained by incomplete lineage sorting. Possible interspecies hybridisation should be tested on a larger sample size with additional nuclear markers. There is no argument for considering S. s. alcamoensis as a subspecies of S. septemplicata , we here consider it a subspecies S. tiberii .

Figures

Figure 1. Wagner's (1913, 1925) and Brandt's (1961) Siciliaria genital drawings A Siciliaria septemplicata, Wagner, 1913: plate 572, fig. 14 B Siciliaria grohmanniana grohmanniana, Wagner, 1925: plate 1, fig. 8 C Siciliaria calcarae calcarae, 1925: plate 3, fig. 25 D Siciliaria ferrox, Brandt, 1961: fig. 1 E overall Siciliaria / Sicania and Sicilian Mauritanica distribution F Siciliaria / Sicania and Sicilian Mauritanica distribution of taxa.

Figure 9. Siciliaria septemplicata (Philippi, 1836), Monte Gallo, Sferracavallo 9.1 whole distal genital organs 9.2 internal distal part of genital organs 9.3 whole distal genital organs 9.4 internal distal part of genital organs.

Figure 10. Siciliaria septemplicata (Philippi, 1836), Monte Gallo, Sferracavallo 10.1 shell 10.2 detail of the aperture 10.3 clausiliar plate 10.4 shell 10.5 detail of the aperture 10.6 detail of the columellar side of last whorl 10.7 clausiliar plate double side.

Figure 25. Siciliaria tiberii tiberii (A. Schmidt, 1868), Capo Rama, Terrasini 25.1 whole distal genital organs 25.2 internal distal part of genital organs. Siciliaria tiberii alcamoensis Brandt, 1961 comb. nov., Piano Margi, Carini 25.3 whole distal genital organs 25.4 internal distal part of genital organs 25.5 detail of the pseudopapilla.

Figure 26. Siciliaria tiberii tiberii (A. Schmidt, 1868), Capo Rama, Terrasini 26.1 shell 26.2 clausiliar plate double side 26.3 shell 26.4 detail of the aperture 26.5 clausiliar plate double side. Siciliaria tiberii alcamoensis Brandt, 1961 comb. nov., Piano Margi, Carini 26.6 shell 26.7 clausiliar plate double side 26.8 detail of the aperture 26.9 shell.