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Pusula bessei Petuch, 2013

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Pusula bessei

Autor: Petuch, E.

Taxon v check-listech zemí*

Severní Amerika: Honduras, Jižní Amerika: Kolumbie

* Výčet zemí nemusí být kompletní



Shell large for genus, inflated, with high domed dorsum; margins thickened and flaring, base rounded; dorsum ornamented with 17 large, prominent, heavily beaded ribs, separated by wide, deep dorsal furrow; aperture thin and narrow; inner edge of lip with 12 large teeth, which correspond to large basal ribs; columella with 13 large teeth and corresponding ribs; basal ribs and apertural teeth sometimes bifurcating; fossula large and well developed, concave and depressed, with 6 large teeth; dorsum colored bright pinkish-tan or reddish-pink, with 3 pairs of large dark brown spots, with one pair at anterior end, one pair at midbody, and one pair at posterior end; dorsal spots and reddish-pink dorsal color separated by white dorsal furrow; beads on dorsal ribs lighter pink in color, speckled with pale brownish-pink; base and margins deep magenta-red, with lighter pinkish-red ribs; interior of aperture and fossula white. Holotype: Length 18 mm, width 13.8 mm, FMNH 328408.
Petuch, E. 2013. Biogeography and Biodiversity of Western Atlantic Mollusks.
Shell between 16 and 19 mm in length, slightly heavy weight, solid and somewhat pyriform. Spire slightly projected, covered by callus. Body whorl pyriform, slightly inflated and rounded, about 80% of total height, with both terminals slightly produced. Anterior terminal tip slightly protruded; posterior tip indented. Dorsum profile roundly elevated, with summit at posterior third, completely covered by ribs - about 14 on average. An incised, long, narrow, clearly defined, smooth dorsal sulcus extends longitudinally across the center of the dorsum, bisecting all of the ribs; the latter forming less developed, slightly prominent nodules adjacent to the furrow. Dorsal ribs irregular, thickened with numerous knobs, and frequently interrupted on both dorsal sides. Ventrum slightly convex, with recurved terminals. Shell periphery slightly callused and sharply edged. Aperture somewhat narrow over its entire length, widened at the fossular section. Aperture slightly curved, especially at the anal canal. Labrum roundly callused, broad, tapered towards the canals, slightly curved, keeled towards its inner margin. Labrum bearing on its inner margin an average of 14 fine denticles. Siphonal and anal canals follow the shell profile. Columella somewhat concave, interior margin slightly curved, narrow and tapering almost vertically inwards. Parietal lip somewhat sinuous, rounded, crossed by an average of 12 ribs. Fossula concave, not clearly delimited from the rest of the columella. Inner fossular edge slightly protruded. Shell colour light reddish brown, with three irregular dark brown patches on mid-dorsum and at either end of the sulcus. Dorsal sulcus white. Knobs of the dorsal ribs and nodules whitish. Ventrum and both canals brilliant red. Ventral ribs, labral denticles, columella and fossula whitish. The shells, even from remote localities, look very uniform. The dorsal sulcus varies in width. The nodules vary in strength. The marginal callosity varies and is occasionally obsolete on the ventral side.
L= 16.3-18.7, W = 76-79% of length, LT = 12 - 16, CT = 12 - 14, RR = 12 - 16; data based on 5 specimens.
Fehse D & Grego J - 2014 - Revision of the genus Pusula (Mollusca Gastropoda Triviidae)

Možné záměny

At 18 mm, Pusula bessei is one of the largest triviids found in the tropical western Atlantic. The new Roatan species is closest to the widespread western Atlantic Pusula pediculus (Linnaeus, 1758) but differs in being a more rounded and inflated shell with a proportionally higher, more domed dorsum; in having coarser and more heavily beaded dorsal ribs; in having proportionally smaller brown dorsal spots; and in being a far more colorful shell, with a bright reddish or pinkish-tan dorsum and white dorsal furrow and bright magenta base and margins. In this last character, P. bessei is also similar to the red-based P. pacei (Petuch, 1987) from the Bahamas but differs in being a much larger shell; in having a lighter-colored dorsum; and in having fewer and more strongly beaded dorsal ribs (Petuch, 1987).
Petuch, E. 2013. Biogeography and Biodiversity of Western Atlantic Mollusks.
The coloration is unique and makes the species one of the most attractive within the Triviidae. At first, Petuch identified this species as Pusula bermontiana. Originally we had identified the shell as ''Pusula pullata" according to the common fallacy that all shells with pink ventrum are "Pusula pultata". However, Cypraea pullata has a completely different shell morphology and coloration. We have examined large lots of P. pediculus from all over the Caribbean Province, Florida, Bahamas and Brazil. According to our studies, there are no features - even the coloration - that would allow the the separation of P. bermontiana from P. pediculus at the specific or subspecific level. Therefore we consider P. bermontiana to be a junior synonym of P. pediculus. Pusula bessei is immediately distinguishable from P. pediculus by the shell coloration e.g. the white dorsal sulcus. Pusula pediculus possesses dark brown bands on both sides of the dorsum that haven not been observed in any specimen of the P. bessei.
Pusula bessei is more similar to P. costispunctata from Florida than to P. pediculus in its coloration. However, P. costispunctata has a uniformly brownish appearance, lacking reddish markings in any part of the dozens of shell studied, lacks a callused shell periphery, and has a less circular outline. The appearance of the dorsal sulcus and the surrounding nodules distinguish the new species from P. costispunctata.
Pusula labiosa has a similar shell outline to P. bessei but differs in its generally spherical, compact appearance, its brown dorsal dots (vs. white for P. bessei), the type locality, and lack of a white sulcus. Pusula bessei is a deep water species whereas P. labiosa is found in the littoral and sublittoral together with P. pediculus and P. costispunctata.
Fehse D & Grego J - 2014 - Revision of the genus Pusula (Mollusca Gastropoda Triviidae)


Type Locality: Found under coral slab in 3 m depth, off Coxon's Hole, Roatan Island, Bay Islands, Honduras. At present, the new triviid has only ever been collected on Roatan Island, to where it may be endemic.
Petuch, E. 2013. Biogeography and Biodiversity of Western Atlantic Mollusks.

Možné záměny

Pusula pediculus (Linnaeus, 1758)

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