Castaneobuccinum, Mclean & Clark, 2023

Mclean, James H. & Clark, Roger N., 2023, Seven new genera and thirty-four new species of buccinoid gastropods (Neogastropoda: Buccinidae) from the Aleutian Islands, Alaska, Zootaxa 5351 (2), pp. 151-201 : 193

Genus Castaneobuccinum n. gen.

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Type species: Buccinum castaneum Dall, 1877 (n. comb.)

Description: Profile tall, moderately broad, whorls rounded, suture deeply impressed, color light to dark chestnut brown (rarely white); shell surface devoid of periostracum, shell thick and heavy, the result of a calcitic exterior layer; with sharply incised, spiral microsculpture, with or without initial carination in early teleconch; final lip inflated, heavily reinforced, with broad anal sinus on shoulder. Operculum with concentric growth, nearly filling aperture.

Remarks: Three previously described varieties of Buccinum castaneum are herein regarded as distinct species Based on morphology and sympatric distribution, and placed in Castaneobuccinum . Buccinum castaneum ( Figs. 20 F–H ), which lacks axial sculpture or has only weakly indicated axial folds near the suture, Buccinum castaneum var. triplostephanum Dall, 1919 ( Figs. 20 K–L ) lacks axial sculpture, but has three (rarely four) low, broad, strong spiral cords, and Buccinum castaneum var. fluctuatum Dall, 1919 (Figs. I–J) which has 14–18 relatively strong, often prosocline axial folds. Buccinum castaneum var. incisulum Dall, 1919 is considered a synonym of this last species. These and four presently described species form a unique complex that is endemic to the Aleutian and Pribilof Islands. They are distinguished from all other Buccinum (s.l.) by 1) thickly reinforced outer lip of the aperture, 2) lack of periostracum, and 3) typically dark brown coloration. Seven species are recognized, all in the Aleutians.

Figures

FIGURE 20. A–E. Aleutibuccinum clarki (Kantor & Harasewych, 1998); A. Paratype, RNC 3924, S of Attu Island, 169 m, 50.7 mm; B. RNC 3925, S of Attu Island, 169 m, 50.1 mm; C. RNC 4371, E of Segula Island, 336 m, 55.6 mm; D. RNC 3962, Seguam Pass, 235 m, 61.1 mm; E. operculum from RNC 3924 (fig. 20 A); F–H. Castaneobuccinum castaneum Dall, 1877; F. Holotype, USNM 108973, Shumagin Islands, 36 m, 65 mm; G. RNC 4722, Tanaga Island, 90 m, 69 mm; H. Radula, RNC 4722, bar = 200 µm; I, J. Castaneobuccinum fluctuatum Dall, 1919; I. Holotype, USNM 205916, Bering Sea, off Saint George Island, 54 m, 90 mm; J. RNC 4731, Petrel Bank, 91 m, 78 mm; K, L. Castaneobuccinum triplostephanum Dall, 1919; K. USNM 108974, Kiska Island, 9 m, 75 mm; L. RNC 5054, SE of Buldir Island, 51 m, 63.8 mm.