Dorsanum miran
Creators: name: Simone, Luiz Ricardo L.
name: Pastorino, Guido
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Neogastropoda
Nassariidae
Dorsanum
Dorsanum miran

description: Dorsanum miran (Bruguière, 1789)
Figs 1–8, 16, 17, 21–42
Buccinum miran: Bruguière 1789: 268.
Buccinum politum Lamarck, 1822: 269 (non Röding, 1789).
Dorsanum miran: Brebion & Ortlieb 1976: 537–548; Harzhauser & Kwoalke 2004: 34.
Complete synonymy in Fischer-Piette 1942: 160; Cernohorsky 1984: 29; Adam & Knudsen 1984: 69; Allmon 1990: 27.
Description:
Shell (Figs 1–5, 8). Fusiform-elongated. Colour pale brown, with weak spiral, purple subsutural band, opaque; some specimens white-purple. Protoconch elongated, smooth, shining, ~ 2 whorls; boundary between protoconch and teleoconch well-defined, orthocline (Fig. 8). Spire pointed, ~1.5 of last whorl. Suture shallow but well-marked. Teleoconch of 7 whorls; first 4 whorls with axial varices, ~ 10 in 4 th whorl, gradually disappearing after 6 th whorl; among varices 5–6 weak cords slightly protruding when crossing varices in the first 2 whorls only (Fig. 8), gradually disappearing in 3 rd whorl. Remaining whorls smooth, opaque, except for growth lines (Figs 1–3, 5). Umbilicus absent. Aperture oval, pale brown, glossy (Figs 1, 5). Siphonal canal short and broad, approximately half of aperture width, left edge truncate, right edge wanting, as continuation of outer lip; left edge marked by two strong spiral folds, superior fold smooth, with sharp edge, inferior fold broad, with several arched, strong growth scales (Fig. 5). Outer lip simple, sharp, rounded (Fig. 2). Inner lip simple, callus narrow, covering right surface of canal. Columella possessing strong spiral folds, located between middle and inferior thirds of each whorl (Fig. 4), ending as right edge of left canal wall, producing small protuberance located between middle and inferior thirds of inner lip (Fig. 5).
Head-foot (Figs 21–25). Head protruded, socket-like (Figs 25, 30: he), wide (~80 % of head-foot width), colour pale cream with minute dark brown pits scattered on tentacles and head. Tentacles well-separated from each other; elongated and narrow, eyes placed on small protuberances at mid level of tentacle, on small ommatophore; proximal half of tentacles about double the width of distal half (Figs 21, 24, 25). Rhynchostome present as longitudinal slit located in middle region of head’s ventral surface (Fig. 25: rh). Foot broad, size about half a whorl when retracted. Sole oval, edges thick and rounded (Fig. 22: fs).Anterior furrow of pedal glands deep, superior and inferior edges thick, extending to a little beyond anterior edge of foot (Figs 21, 22: pg); pedal gland embedded in pedal musculature (Fig. 23: pg). One pair of small metapodial tentacles located in posterior end of foot, originating in dorsal region of edge (Fig. 24: et). Opercular pad elliptical, ~80% as wide as dorsal surface of foot; attachment with operculum occupying ~70% of its area (Fig. 24: oa). Columellar muscle thick, ~1.5 whorl; distal end bifid, with right element wide, left element narrow, encased in furrow formed by columellar fold (Figs 21, 24: cm). Female with small orifice of cement gland located on median line of anterior sole region (Fig. 22: gc); inner space wider than narrow duct (Fig. 23: gc).
Operculum (Figs 1, 6, 7). Elliptical, horny, pale brown. Nucleus terminal, inferior. Outer surface with normal concentric growth lines, forming undulations. Scar oval, occupying about ⅔ of inner surface, somewhat dislocated closer to inner edge.
Mantle organs (Figs 26–28). Mantle edge simple, thick. Siphon long, extending beyond mantle edge for 3–4× its base width (Fig. 28: si). Low, broad fold of siphon’s right base separates anterior end of osphradium and gill. Osphradium ~ ¼ width and length of pallial cavity; anterior end pointed, strongly curved towards left; posterior end round-ed; osphradium filaments symmetrical, long, bluntly pointed, basal edge reinforced by wide rod (Fig. 26: os). Area between osphradium and gill very narrow. Ctenidial vein (cv) narrow, width uniform along its length. Gill (gi) ~ 80 % of pallial cavity length and ~ ½ its width; anterior end broadly pointed, located at some distance from mantle edge. Afferent gill vessel very narrow, lying at a short distance from right edge of gill (Fig. 26: af). Gill separated from right edge of pallial cavity by an area equivalent to its width. Hypobranchial gland thin, beige, covering most of area between gill and rectum, including left and ventral surfaces of rectum (Fig. 26: hg). Rectum narrow, with thick walls, running along right edge of pallial cavity (Fig. 26: rt). Anus simple, siphoned, located in front of anterior quarter of pallial cavity (Figs 28, 36: an). Pallial gonoducts located between rectum and right pallial edge, described below.
Visceral mass (Figs 28, 40).Anterior quarter of whorl mostly occupied by kidney (ki) and pericardium (pc). Digestive gland beige, located along inferior region of each visceral whorl, covering middle digestive tubes and also two whorls posterior to stomach. Gonad pale beige, lying along superior and columellar surfaces of visceral whorls posterior to stomach. Stomach small, located half a whorl in front of pallial cavity (Fig. 40: st).
Circulatory and excretory systems (Figs 28, 40). Pericardium (pc) located just posterior to gill, along left anterior region of visceral mass.Auricle (au) small, triangular, attached to anterior surface of pericardium, with ctenidial vein entering from left and connected to kidney at its right end. Auricle connected to anterior surface of ventricle. Ventricle (ve) very large, filling most of pericardium. Aortas located along postero-left region of ventricle. Kidney occupying ~ ⅛ of pallial cavity, located along middle and right regions of anterior end of visceral mass. Nephridial gland triangular in section; lying along dorsal region of reno-pericardial wall. Renal lobe transversely folded, occupying most of kidney’s interior volume (Fig. 40: ki); intestine runs through it.
Digestive system (Figs 29–35). Proboscis as long as foot (Figs 21, 24: pb). Mouth circular, on proboscis tip (Figs 24, 29–31: mo). Buccal cavity with a pair of broad and low dorsal folds (Fig. 31: df), occupying ~⅓ of dorsal wall, with equivalent distance between them. Odontophore oval, ~70 % of length of proboscis (Figs 29, 30: od). Odontophore tube connects it with buccal cavity, length equivalent to ~ ¼ of odontophore length, possessing mostly longitudinal muscles (Figs 29, 31: oo). Odontophore muscles (Figs 29–35): m1, several small muscle fibres connect buccal mass to adjacent inner surface of proboscis, one more developed pair originating in peribuccal lateral region of proboscis, running posteriorly, inserting in lateral side of anterior third of odontophore (Fig. 29: m1); m 1t, pair of narrow, lateral, transverse protractor muscles of odontophore, originating in lateral region of proboscis, running posteriorly and penetrating membrane surrounding odontophore, inserting in odontophore cartilage in region just posterior to m6 (Figs 32, 33); ma, peribuccal muscles and protractor of odontophore bearing longitudinal fibres, origin thin within dorsal wall of oral cavity, running along odontophore tube and becoming thicker, inserting into outer surface of cartilages externally to m6 and medially to m4 (Figs 32–34); mc, single, circular constrictor muscle converting dorsal surface of odontophore, inserting along outer side of dorsal edge of cartilages at along ~ 80% their length (Figs 32, 34); m2, main pair of retractor muscles of odontophore, relatively narrow, originating in ventral surface of haemocoel in region just posterior to proboscis, running dorsally, with median fibres running through nerve ring, inserting into posterior end of cartilages (Figs 29, 30, 32–35); m2a, auxiliary of m2, being single and running between both m2 muscles, inserting on radular nucleus together with small branch of aorta (Figs 32–34); m2b, broad and thick auxiliary pair of m2 and dorsal tensor muscles of radula, originating as m2, running more medially, inserting along radular sac in its mid-region (Figs 32–34); m2c, ventral single, thin muscle auxiliary of m2, originating on ventral medial fibres of m2a, detaching from it in region just posterior to m6, runs covering medial region of m6, inserting on median-posterior region of ma (Fig. 33); m4, strong pair of dorsal tensor radular muscles, originating in odontophore cartilages on posterior-ventral surface, running towards dorsal surrounding lateral surface of cartilages, inserting laterally along radular sac (Figs 33–35); m5, pair of secondary dorsal tensor muscles of radula, originating in posterior-dorsal surface of cartilages, running dorsally and medially, joining with m4, inserting into radular sac alongside and medial to m4 insertion (Figs 33–35); m6, thin horizontal muscle, uniting both odontophore cartilages just posterior to anterior fusion for about 70 % of cartilage length, inserting along ventral and internal edge of cartilages, gradually becoming broader posteriorly (Figs 33, 35); m8, a pair of thick cartilages shorten muscles, which are located along dorsal edge of anterior region of cartilages for almost half their length, being thicker anteriorly and gradually narrowing posteriorly (Figs 34, 35); m9, one or two pairs of very narrow protractor muscles of radula, originating on posterior half of dorsal edge of cartilages, running forwards medially, inserting along m2a anterior fibres (Figs 34, 35); m9a, pair similar to m9, originating in anterior region of ventral edge of cartilages, just centrally to posterior region of m8, running medially and dorsally, inserting together with m2b fibres at level anterior to radular nucleus (Figs 34, 35); m11, pair of ventral tensor muscles of radula, thin, somewhat broad, originating in posterior-ventral end of cartilages, running anteriorly and medially covering m6, inserting into ventral edge of radula and subradular cartilage, and some inner portions in front of this (Figs 32–35). Subradular cartilage expands in exposed region of radula into buccal cavity, covering neighbouring surface of radula; oc, odontophore cartilages, elongate, furrow-like, flat, ~20× longer than wide; fusion between both cartilages in anterior-medial end, along ~5% of their length (Fig. 35); subradular membrane covers inner surface of subradular cartilage and radula, m4, m5 and m11a insertions.
Radula (Figs 16,17): rachidian tooth wide, comb-like, occupying about half of radular width; curved base, width ~ 5× greater than its length; ~17 triangular, sharp pointed cusps of similar size, except for some diminishment towards the side; lateral tooth hook-like, bicuspid, base broad (equivalent to ½ of rachidian base width), obliquely disposed; main lateral cusp widely curved inwards, about as long as base; secondary, medial cusp approximately half the size of lateral cusp; both cusps separated from each other by smooth area equivalent to ⅓ of tooth’s width. Salivary glands cluster around oesophagus along region of valve of Leiblein and ventral ganglia of nerve ring, attached to lateral surface of anterior oesophagus just anterior to valve of Leiblein (Figs 29, 30: sg); their ducts very narrow, except for short proximal region that runs completely attached to anterior oesophagus wall and, more anteriorly, inside dorsal folds of buccal cavity (Fig. 31: sd); opening is a very small pore (Fig. 31: sa), into anterior-middle region of dorsal folds of buccal cavity. Anterior oesophagus with somewhat thick walls, a little longer than proboscis; inner surface with 12–15 narrow, uniform longitudinal folds. Valve of Leiblein about of odontophore volume, anterior region with transverse, white band bearing long cilia, middle and posterior regions white, corresponding to inner gland that occupies most of inner surface; oblique furrow (bypass) absent (Fig. 29: vl). Middle oesophagus ~10 % of anterior oesophagus length (Fig. 29: em), walls thin; inner surface similar to that of anterior oesophagus; aperture of gland of Leiblein is a minute pore. Gland of Leiblein narrow and elongated (Figs 29, 30: gl), ~3× longer than middle oesophagus; anterior region approximately double the length of middle oesophagus width, becoming gradually narrower towards posterior. Duct of gland of Leiblein short and narrow (about 3× shorter than middle oesophagus, and about half of its diameter) (Fig. 29). Posterior oesophagus (Figs 29, 30, 40: ep) about as long as anterior oesophagus, inner surface with 12–15 narrow, tall, irregular, sometimes coalescent longitudinal folds. Stomach oval, blind sac, ~ ¼ width of adjacent visceral whorl; located about half a whorl posterior to pallial cavity, positioned approximately in the middle (Fig. 40: st). Oesophageal insertion and intestinal origin united in anterior, left side of stomach, additionally having 3 narrow ducts to digestive gland in the sa me region (Fig. 40: dd). Inner gastric surface mostly smooth. Intestine about as wide as posterior oesophagus; sigmoid visceral loop (Fig. 40: in) is in digestive gland, with region in front of rectum passing though ventro-left side of kidney. Rectum and anus described above (pallial cavity).
Genital system. Male (Figs 36–39). Visceral structures not seen in detail. Prostate spans about ⅓ of pallial cavity length, narrow, closed (tubular), lying ventrally to rectum (Fig. 36: pt). In region posterior to anus, vas deferens gradually crosses to pallial cavity floor, narrow; walls relatively thick, running relatively straight up to penis base (Fig. 38: vd). Penis slender, about as long as pallial cavity, its length ~15× greater than its width, dorso-ventrally flattened (Figs 37, 38); base narrow, located just posterior to right tentacle; middle level twisting, narrowing gradually up to bluntly pointed tip (Fig. 37). Penial duct runs approximately along centre of penis, very narrow, intensely coiled in basal half, somewhat straight in distal half (Fig. 37: pd). Penial aperture apical, very small, inside wide preputial chamber (Figs 37, 39: ph), aperture in middle region of chamber’s basal surface, as small papilla (Fig. 39: pp); preputial chamber occupying of penis volume, its aperture wide, inclined to the right (Fig. 39).
Female (Figs 27, 28). Visceral oviduct very narrow, running along middle region of columellar surface of last whorl of visceral mass, located in front of pallial cavity by ~¼ whorl (Fig. 28: vo). Posterior region of pallial oviduct protrudes into kidney. Albumen (whitish – ag) and capsule (beige – cg) glands adjacent, albumen gland spanning posterior of pallial oviduct.Seminal receptacle absent. Capsule gland with flat lumen, vaginal furrow runs along its left edge, with smooth surface (Fig. 28: cg). Female pore narrow, weakly protruded, papilla-like, with thick edges (Fig. 28: fp). Bursa copulatrix located as terminal portion of pallial oviduct, small, short; with thick muscular walls (Fig. 27: bc); its aperture turned ventro-anteriorly as female pore (Fig. 28: fp); inner surface with low, wide, longitudinal folds. Cement gland in pedal sole described above (head-foot) (Figs 22, 23: cg). Central nervous system (Figs 41, 42). Well-concentrated, connectives and commissures indistinct; total nerve ring volume ~ of haemocoel. No distinction between pleural and cerebral ganglia (ce). Cerebral ganglia broadly connected to each other; commissure approximately half the length and width of each cerebro-pleural mass. Pedal ganglia (pu) slightly smaller than cerebro-pleural ganglia; pedal commissure broad, indistinct. Cerebro-pedal and pleuro-pedal connectives short, indistinguishable. Pair of buccal ganglia (bg) small, located close to posterior edge of cerebral ganglia. Suboesophageal ganglion (su) the size of about half the cerebro-pleural ganglion, shortly and broadly connected to right cerebral ganglion (Fig. 42).
Measurements of shells. MNHN: 1♀: 22.9 × 9.8 mm; 2♂: 23.1 × 9.9 mm.
Distribution: West African coast, from Morocco, Western Sahara, Mauritania, Senegal, Ivory Coast and Gabon (Adam & Knudsen 1984; Allmon 1990).
Habitat: Sandy bottoms, ~ 15 m depth.
Material examined: 1♂ 2♀ MOROCCO: Agadir Bay; Qued Sours, off Sousse River estuary, 30°22'N 09°37.9'W, 15 m depth, (Radial I; sandy bottoms, Moukrin & Gofas col. 08.v.1999), MNHN. SENEGAL: ANSP 34627, several shells; Dakar, USNM 617323, 1 shell.
Type remarks: Cernohorsky (1984) illustrated a syntype of Buccinum politum housed at the MHNG (1101/99) and one syntype of Buccinum miran after Fischer-Piette (1942) from the MNHN.
description: Published as part of Simone, Luiz Ricardo L. & Pastorino, Guido, 2014, Comparative morphology of Dorsanum miran and Bullia granulosa from Morocco (Mollusca: Caenogastropoda: Nassariidae), pp. 125 in African Invertebrates 55 (1) on pages 127-135, DOI: 10.5733/afin.055.0107, http://zenodo.org/record/7671948