Macrocypraea cervus (Linnaeus, 1771)

Figs 3G–3K, 3N–3P, 4D–4E, 8–10 and 11–11F

Synonymy see [2]. Complement:

Cypraea cervus Linnaeus, 1771 [15]: 548.

Macrocypraea cervus: Meyer, 2003[16]: 411; Soriano, 2006[17]: 49, Table 3; Rosenberg et al., 2009[18]: 636; Lorenz, 2017[2]: 287, text figure., pl. 58.

Macrocypraea (Lorenzicypraea) cervus: Petuch & Drolshagen, 2011[19]: 121–122.

Type locality. Not stated.

Diagnosis. Shell large (~ 120 mm), with very numerous minute whitish spots, never ocellated, aperture widening anteriorly. Mantle lobes papillae small, simple, slender, very numerous. Hypobranchial gland very thick. Osphradium small, with branches very narrow. Kidney with lobe wide, with radial arrangement. Odontophore pair m3 twofold (m3, m3a). Anterior esophagus with distinct gland. Pallial spermoduct with edges strongly asymmetrical. Albumen gland clearly narrower than capsule gland. Bursa copulatrix simple, curved.

Distinctive description

Shell (Figs 3G–3K, 3N–3P and 11A–11F). Shell description in Lorenz ([2]: 287). Pair of anterior projections flanking canal ~1/8 of shell length (Fig 11A and 11C). Inner lip slope with teeth relatively short, perpendicular to longitudinal axis (Fig 11E); anterior concavity preceding canal relatively small (~1/3 of local shell height), lacking ventral nodules (Fig 11D and 11F). Left edge of canal oblique (Fig 11E).

Head-foot (Fig 8A and 8B). Characters similar to M. mammoth. Distinctions as follows: Cephalic tentacles more ventrally positioned. Pairs of retractor muscles of proboscis (Fig 8E: rm) of equivalent size. Proboscis much shorter (described below).

Mantle organs (Fig 8C and 8D). Similar to M. mammoth. Distinctions and remarks as follows: Outer surface of exposed part of mantle dark brown, bearing many relatively small, somewhat uniformly distributed papillae (mp). Each papilla mostly cylindrical, distal end tapering up into sharp pointed tip (Fig 8D: mp), base rarely narrower than middle region; profile broad, rather cylindrical. Siphon (si) bearing series of small papillae along its margin. Osphradium (os) much smaller, occupying ~1/30 of pallial roof area, widely separated from siphon and gill. Osphradium with three branches of roughly similar size and shape, each encompassing ~1/2 of total osphradium length. Each gill filament taller, narrower, triangular, tip sharper (Fig 8D: gi). Distance between gill and visceral mass very close to kidney in posterior half, suddenly becoming far from kidney in anterior half. Hypobranchial gland thicker (hg).

Visceral mass (Fig 8A, 8C and 10A). Same characters as M. mammoth.

Circulatory and excretory systems (Fig 10A). Similar to M. mammoth.

Digestive system (Figs 9B – 10A). Most attributes similar to M. mammoth. Distinctions and notable features as follow: Proboscis much shorter (Fig 8E: pb), length ~1/3 of haemocoel length, volume ~30% of haemocoel volume. Buccal mass occupying ~1/4 of haemocoel volume, protruding beyond proboscis. Pair of dorsal folds of buccal cavity (df) slightly narrower; dorsal folds becoming narrow, separated from each other in their middle level, space between folds bearing two series of narrow, slightly oblique smaller folds (Fig 9B: ff) delimited by pair of taller folds (ef) as continuation from buccal dorsal folds, running along entire middle esophagus, fading in posterior third of esophageal gland (Fig 9B). Odontophore muscles (Fig 9A) also similar, differing by m1b) composed of three pairs of narrow jugal muscles, functioning as dorsal protractor muscles, relatively flattened, originating on latero-dorsal surface of mouth, extending postero-dorsally, inserting into dorso-lateral outer wall of buccal mass; m4d) absent; m3) similar characters but twofold (Fig 9A: m3 + m3a), with inner pair (m3a) smaller and thinner; m10, m11, m14) pairs of similar features, but much narrower and thinner. Radular teeth (Fig 4D and 4E) also similar, differences as follows: rachidian tooth ~30% narrower, terminal cusp curved forwards (instead of inwards); lateral tooth with sharper pointed tip, straight (instead of undulated); both marginal teeth also similar, straight, with sharper pointed tip. Salivary glands slightly larger (Fig 9A: sg). Salivary ducts also opening in middle level of dorsal folds, but positioned more laterally, at middle of dorsal fold width (Fig 9A; sa). Dorsal folds flanking pair of sets of longitudinal folds (Fig 9B: ff), ending before anterior esophagus. Anterior esophagus bearing lobes of glandular tissue (Fig 9A and 9B: eg); inner surface with a pair of tall longitudinal folds (extension of dorsal folds of buccal mass) (ef). Middle esophagus with pair of folds (ef) coming from anterior esophagus, running along large esophageal gland aperture (ec); this pair of folds fading before posterior region of esophagus. Stomach large (Fig 8C), u-shaped, located about in penultimate whorl of visceral mass (Fig 8C: st);

https://doi.org/10.1371/journal.pone.0225963.g011

esophagus inserting into its left side with no clear distinction. Mid and hindgut (Fig 8C) similar to preceding species. Anus narrow, siphoned (Fig 8C: an).

Genital system. Male. Similar to M. mammoth, except for: branch of testis at left of seminal vesicle (Fig 10A: inferior ts); Seminal vesicle (Fig 10A: sv) coiled in T-fashion, with its left coils slightly broader than the right ones. Opened sperm grove (Figs 8B and 10B: ps), flanked by relatively thick edges, with left edge narrower and taller than right edge mainly in its posterior region. Penis (Figs 8B and 10B: pe) slightly broader, lacking penial gland in its middle region.

Female (Fig 8C). Features similar to M. mammoth. Notable features as follows: Visceral oviduct slightly more convolute. Albumen gland of pallial oviduct (ag) ~1/3 of capsule gland width, with similar length. Bursa copulatrix (bc) also balloon-shaped, but narrower and simpler, composed of a single blind-sac structure bent to the right; inner surface bearing 7–8 tall longitudinal folds.

Central nervous system (Fig 10C). Cerebral (ce) and pedal (pn) ganglia very close to their counterparts, commissure indistinct. Pair of cerebral ganglia occupying ~1/40 of haemocoel volume. Pleural ganglia (gp) partially fused to cerebral ganglia, with indistinct limits. Supra and suboesophageal ganglia (su) located dorsally, each connected to adjacent cerebral ganglia, size ~1/4 of cerebral ganglion size, bearing connective between them as wide as their own width. Pair of cerebro-pedal and pleuro-pedal connectives relatively symmetrical, long, their length ~twice cerebral ganglia width. Pair of pedal ganglia (pn) ~70% of cerebral ganglia size, almost spherical.

Distribution. South Florida to north of Cuba.

Habitat. Rocks and corals, subtidal, 0–53 m [18].

Material examined. USA: Florida; Florida Keys, off Marathon (E. Malone col., 1970), MZSP 121238, 1 shell, MZSP 121239, 1 shell, MZSP121240, 1 shell (ex. Colella collection), SE point of Big Pine Key, ANSP 93276 (A6307), 1♀ (H.A. Pilsbry col., 1907, ex C.B. Moore), Bahia Hondo Key, 24˚40’04”N 81˚15’55”W, ANSP 216746 (A15658), 1♂ (A.J. Ostheimer col., 2. vi.1958); Indian River, off Wabasso, sand flat north of rest area on causeway state route 512, 27˚45.943’N, 80˚25.257’W, MZSP 46866, 1 shell (Simone col., 5/VIII/2004); Keys, N of Keys Marine Laboratory, 24˚49.78’N 80˚48.51’W, MZSP 36106, 1♂, 2♀ (Simone col., 22.vii.2002). CUBA: Cienfuegos Province; off Cienfuegos city, 2–4 m, MZSP 115362, 1 shell (under dead corals, local people col., vi.2000, ex Femorale). MEXICO: Gulf of Mexico, MZSP 8149, 1 shell (Sowerby col., 1896). COSTA RICA: Western Coast, Tamarindo Bay, left of Hotel Rocky Point. 17˚N, 85˚20’W, MZSP 131503, 1 shell (B. Cook coll., 1/ii/1982).

Measurements (height, length, width in mm). MZSP 8149: 64.1 by 136.3 by 80.0; MZSP 46866: 36.5 by 71.4 by 41.0; MZSP 115362: 44.2 by 92.2 by 55.5; MZSP 121238: 47.7 by 98.5 by 57.2; MZSP 121239: 44.2 by 95.5 by 55.4; MZSP 121240: 55.7 by 116.2 by 67.7.

Remarks. Macrocypraea cervus also has some anatomical exclusivities that have been explored in the present comparative description. Some are particularly interesting, e.g., the slender, small, and more numerous papillae of the mantle lobes (Fig 8C and 8D: mp), the thick hypobranchial gland (Fig 8C: hg) reinforced by wide transverse septa, and the very narrow osphradium branches (Fig 8C: os). The wide renal tissue clearly organized in radial folds (Fig 10A: ki), the two-folded odontophore pairs m3 (Fig 9A: m3, m3a), the clear, bulging glandular region of the anterior esophagus (Fig 9A and 9B: eg), the strong asymmetry of pallial spermoduct edges (Fig 10B: ps), mainly in its posterior region, the clear distinction of width between the albumen and capsule glands in the pallial oviduct (Fig 8C: ag, cg), and the bursa copulatrix comprised of a simple, bent sac (Fig 8C: bc) are also noteworthy exceptionalities.