Page 4 - Romani_Pagli_2020

agos (NE Atlantic) (Verduin, 1984; Hoenselaar H.J. & cept 5-6 regular spiral threads, evenly running and
Hoenselaar J., 1994; Segers et al., 2009; Rolán et al., slighly raised (Fig. 1. C, D). Teleoconch with no axial
2011). This odd locality was later disproved by exam- sculpture except for orthocline growth lines. A subsu-
ination of the original sample, including Atlantic spe- tural spiral furrow begins immediately after proto-
cies not living in the Mediterranean Sea, a labelling conch/teleoconch transition and runs for 1.5-2 whorls,
error was probably cause of this mismatch. However sometimes up to the outer lip. 15-20 incised spiral
take this opportunity to highlight the morphological grooves are present last whorl, narrower than interspaces
differences between these two taxa and give some in- and stronger around the base. Aperture oval, drop-
formation on C. marioni. shaped, total height/apertural height ratio 2.3-2.6. Out-
er lip rounded, without denticles inside. Seen from
aside, the edge of the outer lip is S-shaped, slightly
Materials opisthocline, with the concavity near the suture. Umbil-
icus reduced to a narrow chink. Fresh shells are colour-
Material was collected from bioclastic bottoms by SCU- less, old ones white.
BA diving or obtained through the analysis of by-catch
of commercial trawling. Comparisons were done with Crisilla cristallinula (Manzoni, 1868) (Fig. 1. H-L).
material figured in recent papers and samples from sev- Shells from Canaries show a somewhat sturdier appear-
eral localities (see below). Shells were examined through ance, stronger scuplture and slightly more thickened
Lomo MBC-10 stereomicroscope and photographed outer lip. They are identical to the above mentioned
with a Canon EOS 400D camera, while measurements shells in all other respects.
were carried out by means of an eyepiece micrometer.
Protoconch whorls were counted according to Verduin Crisilla marioni (Fasulo & Gaglini, 1987) (Fig. 1. E-G,
(1977). Shell and details were examined with both XL30 Fig. 2. A-D). It is superficially similar to C. cristallinula,
and Quanta 200 SEM in the Centro de Apoyo Científico but attains a larger size. Shells are stouter, with an oval
y Tecnológico a la Investigación (CACTI) - University of outline, whorls more convex, aperture proportionally
Vigo, after air drying and mounting on SEM stubs, and larger, outer lip clearly thicked. The first 1-2 teleoconch
Jeol, JSM-5400 SEM at Dipartimento di Scienze Biologi- whorls lack a marked sculpture, except for a pair of sub-
che, Geologiche e Ambientali, Bologna University. sutural furrows delimiting a conspicuous subsutural
Updated taxonomy and nomenclature follow Mollusca cord and a less evident one (Fig. 6). The last whorl has a
Base (2020). densely reticulate surface due to the intersection of
Abbreviations and acronyms. APC: Attilio Pagli collec- spiral grooves with axial riblets (Fasulo & Gaglini, 1987; Repetita juvant: once again on Crisilla cristallinula (Manzoni, 1868) and Crisilla marioni (Fasulo & Gaglini, 1987) (Rissoidae: Gastropoda)
tion (Empoli); CBC: Cesare Bogi collection (Livorno); Scaperrotta et al., 2011) (Fig. 2. A-D). The protoconch
LRC: Luigi Romani collection (Lucca); SBC: Stefano & sculpture (Fig. 1. G) is very weak, irregular, somewhat
Maria Bartolini collection (Firenze); SEM: Scanning Elec- rugose on the nucleus, subsequently shows well raised,
tron Microscope. irregular spiral threads, often broken off, sometimes
oblique and confluent.
Examined material In some populations can be found “small” specimens
(Fig. 1. E-G) having shells 1.5-1.7 mm in height with well
Crisilla cristallinula: 4 shells, off Gran Canaria Island developed labial varix. They mostly lack the typical re-
(Spain), 100-120 m depth; 2 shells, off Tenerife Island ticulate pattern on the last whorl due to the absence of
(Spain), all in CBC. Crisilla cfr. cristallinula: more than conspicuous axial sculpture, while spirals are obsolete
50 shells, unknown locality [stated as “off Algiers (Alge- except in the basal area. These “small” specimens can
ria), 70 m depth”], in APC. Crisilla marioni: 18 shells, mimic large C. cristallinula shells, but can be distin-
Palmaiola Islet (Livorno, Italy), 20 m depth, in APC. guished for their stocky shells and for the typical proto-
More than 100 shells, Capraia Island (Livorno, Italy), 20 conch features.
m depth; 3 shells, off Capraia Island (Livorno, Italy), 350
m depth; 2 shells, off Gorgona Island (Livorno, Italy),
500 m depth; 27 shells, Giannutri Island (Grosseto, Italy), Discussion
50 m depth; more than 50 shells, L’Île­Rousse (Corsica,
France), 30-40 m depth, all in SBC; more than 50 shells, The “Algerian” shells have a strong resemblance with C.
off Egadi islands (Trapani, Italy), 300 m depth, in LRC. cristallinula, and are very probably conspecific. We re-
frain from assigning them to this species only for the
lack of reliable collecting data. Anyway, as the true C.
Results cristallinula, they can be easily distinguished from C.
marioni.
Crisilla cfr. cristallinula (Manzoni, 1868) (Fig. 1 A-D). These two species were not clearly separated until
Shell small, height up to 1.7 mm (Fig. 1. A, B). quite Hoenselaar H.J. & Hoenselaar J. (1994) adequately de-
solid, semitransparent, conical, with slightly convex scribed and illustrated the differences between them.
whorls and shallow suture. Protoconch paucispiral of Here we confirm their statements, adding some features
about 1 whorl. Protoconch dome-shaped, smooth ex- and giving more detailed pictures. 101