“Tractolira germonae new species
(figures 1-3, 5-13; table 1)
Description: Shell (figures 1-3) to 60 mm, extremely thin, translucent, elongate, fusiform, eroded where not covered by periostracum (figures 5, 7). Protoconch badly eroded on all specimens, with vestiges of projecting calcarella at apex. Shell with up to five moderately convex. whorls. Suture impressed. Spiral sculpture of 60-80 fine threads on body whorl, 20-30 on preceding whorls, decreasing in prominence with increase in shell size. Axial sculpture limited to fine growth striae. Aperture ovate. Outer lip smooth, slightly flared in larger specimens. Inner lip smooth, with thin transparent inductura along parietal region. Columella smooth, with raised white siphonal fold. Outer shell layer white to light tan, eroded areas of shell white, aperture white. Periostracum (figure 5) thin, greenish brown. Inner shell surfaces smooth, continuous.
Ultrastructure: Shell of three orthogonal lavers of crossed lamellar crystals: outer layer 20 µm thick, with crystal faces perpendicular to growing edge; middle layer 120 µm thick, with crystal planes colabrally aligned; inner layer 12 µm thick, with crystal planes again perpendicular to growing edge. X-ray diffraction analysis showed shell to be composed almost exclusively (> 99%) of aragonite, with no significant amounts of calcite or vaterite.
External anatomy: Soft parts comprise three whorls, mantle cavity spans ½ whorl, kidney ⅓ whorl, digestive gland two whorls. Foot (L/W = 1.5) broad anteriorly, tapering posteriorly, with deep propodial mucous gland (figure 9, pmg). Operculum absent. Animal yellowish tan, without visible color pattern in alcohol-preserved material. Sole of foot deeply glandular, producing copious mucus. Siphon (figure 9, s) muscular, free, about 1/5 shell length. Two ventral appendages, equal in length, extend from base of siphon (figure 9, sa), one on each side of left cephalic tentacle (figure 9, t). Head broad, with short tentacles on each side of hood that extends over rhynchostome. Outer edges of tentacles with broad semicircular projections. Eyes absent.
Mantle cavity: Arrangement of mantle cavity organs similar to that of Alcithoe arabica as described by Ponder (1970). Mantle edge thickened, muscular, smooth. Osphradium with 46 filaments below and 60 above osphradeal ganglion. Ctenidium, of about 200 filaments, slightly narrower (0.9 × ) and about 1.4 times as long as osphradium. Hypobranchial gland deeply glandular, producing purple secretion. Pericardium forms left rear wall of mantle cavity, ventricle diameter 2.5 × auricle diameter.
Alimentary system: Proboscis short, broad, pleurembolic, partially protruded in majority of specimens examined (figure 9, pb). Proboscis retractor muscles attached to walls of cephalic hemocoel. Mouth (figures 9, 10, m) triangular. Buccal mass (figure 10, bm) muscular. Radular ribbon short (5-7 mm), uniserial with 48-56 teeth, each with three tusk-like cusps. Central shorter and narrower than outer cusps (figure 8). Accessory salivary glands (figure 10, asg) wrapped tightly around salivary glands (figure 10, sg). Ducts of accessory salivary glands join (figure 10, dasg) before entering buccal cavity ventrally. Ducts of salivary glands run along the esophagus, entering buccal cavity dorso-laterally. Valve of Leiblein (figure 10, v1) large, nearly spherical. Gland of Leiblein (figure 10, gl), long, tubular, highly convoluted, fills posterior ⅔ of cephalic hemocoel. Posterior esophagus (figure 10, pe) reflected dorsally before joining U-shaped stomach. Section of stomach anterior to single duct from digestive gland (figure 11, ddg) tubular, with longitudinal folds. Posterior to digestive gland duct, stomach forms caecum (figure 10, c), becoming transversely pleated before joining intestine (figure 10, int). Intestine with longitudinal folds, expands into pink rectum (figure 10, r), with jade green anal gland (figure 10, ag) along distal ⅓ of its length. Anus (figure 10, a) with muscular rim and ventral papilla.
Female reproductive system: Ovary ascinous, whitish, on columellar side of digestive gland. Oviduct (figure 12, od), thin, leading to rear of mantle cavity and entering anterior ventral edge of albumen gland (figure 12, ag), which forms right wall of kidney. Pallial oviduct is joined by the purplish ingesting gland (figure 12, ig) before expanding into capsule gland (figure 12, cg). Bursa copulatrix (figure 12, bc) forms blind muscular diverticulum between female opening (figure 12, fo) and capsule gland.
Male reproductive system: Testis yellowish tan, lines right side of digestive gland. Testicular duct tubular, passing along pericardium before entering mantle cavity. Prostate gland (figure 13, pr) slit ventrally, spans posterior half of mantle cavity. Prostate and rectum surrounded by connective tissue (figure 13, co) to form cylindrical mass. Vas deferens (figure 13, vd) descends to mantle floor, forming groove with fused edges that runs to base of penis (figure 13, pen). Penis short, dorsoventrally flattened, reflected posteriorly, with terminal papilla (figure 13, pap). Penial duct as in Alcithoe arabica (Ponder, 1970: fig. 32).
Kidney: Kidney similar to that of Alcithoe arabica (Ponder, 1970: fig. 33), consisting of nephridial gland adjacent to pericardium, heavily pleated dorsal area, and ventral area with seven large lamellae. Latter two areas each fed by branch of the renal vein. Kidney opening over renal vein on left side of kidney. Reno-pericardial opening at anterior upper left corner of kidney.
Nervous system: Nervous system Type 2 (Ponder, 1970: 159), with supraesophageal and right pleural ganglia fused.
Etymology: This species honors Mrs. Raye N. Germon, Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, for her contributions to the study of Antarctic mollusks.
Type locality: East of Candlemas Island, South Sandwich Islands, 57°00.4'S, 27°10.1'W, in 2,740-2,757 m, Islas Orcada Cruise 575, sta. 38, May 22, 1975.
Holotype: USNM 859076, ♀, length 59.1 mm.
Paratypes: Paratypes 1-4, USNM 845611, from the type locality; paratypes 5-10, USNM 845612, paratype 11, ANSP A 11540, paratype 12, BM(NH) 198141, 57°22.6'S, 26°34.0'W, in 2,248-2,402 m, May 26, 1975, IO-575, sta. 51; paratypes 13-16, USNM 845613, 57°39.0'S, 26°00.4'W, in 2,380-2,609 m, May 27, 1975, IO-575, sta. 54; paratypes 17-19, USNM 845614, 56°29.5'S, 26°46.9'W, in 2,248-2,387 m, May 30, 1975, IO-575, sta. 63; paratypes 20-29, USNM 845615, paratypes 30-31, DMNH 169441, 56°03.5'S, 26°58.3'W, in 2,128-2,161 m, June 3, 1975, IO-575, 53°25.2'S, 45°17.0°W, in 2,632-2,691 m, June 12, 1975, IO-575, sta. 104.
Distribution: All live-collected specimens were taken off the South Sandwich Islands, with one record, based on shell fragments, from the Scotia Ridge. The confirmed bathymetric range for T. germonae is 2,161-2,740 m, with a mean station depth (n = 6) of 2,449 m. This species appears to be endemic to the Scotia Arc.
Ecology: All specimens of this abyssal species were taken on mud bottoms. Upper whorls of even the smallest specimens are eroded. The periostracum protects the shell from dissolution (figure 5), as this species lives below the aragonite compensation depth (Morse & Berner, 1979). A radular ribbon belonging to a naticid of the genus Amauropsis (Powell, 1951: fig. J) was found in the stomach of a dissected specimen.
Table 1. Tractolira germonae new species. Measurements of shell and radular characters. Linear measurements in mm. n = 10.
Character
X
Range
SD
Shell length
50.0
35.9-59.2
6.9
Aperture length
27.0
21.4-30.1
3.2
Shell length
Aperture length
0.540
0.503-0.586
0.028
Total # whorls
4.75
4.25-5.00
0.25
Spire angle
31.8º
28.8º-37.6º
2.8º
Radular length
6.2
5.0-6.8
0.6
# Radular rows
52.4
48-56
2.7
Comparative remarks: Tractolira germonae differs from T. sparta Dall, its only living congener, in having a broader, less elongate shell with a proportionally larger aperture, in lacking axial ribs on the early whorls and in having broader, less pronounced spiral sculpture. Neither preserved material of T. sparta nor the radula described by Dall are available, and anatomical comparisons cannot be made, other than to note that the radula of T. germonae resembles that of Miomelon philippiana (Dall, 1896) (Pilsbry & Olsson, 1954: pl. 3, fig. 9), therein agreeing with Dall's (1907:365) description of the radula of T. sparta. The holotype of Tractolira sparta was illustrated by Dall (1908). The specimen figured by Weaver and duPont (1970: pl. 56 G, H) as the holotype is a paratype (USNM 123000) from Malpelo Island, Colombia. The holotype of T. sparta is figured herein (figure 4).”
(Harasewych, 1987: 3-7)
Tractolira germonae is a species of sea snail, a marine gastropod mollusk in the family Volutidae, the volutes.[1]
Tractolira germonae is a species of sea snail, a marine gastropod mollusk in the family Volutidae, the volutes.
Tractolira germonae is een slakkensoort uit de familie van de Volutidae.[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1987 door Harasewych.
Bronnen, noten en/of referenties
Tractolira germonae là một loài ốc biển, là động vật thân mềm chân bụng sống ở biển trong họ Volutidae, họ ốc dừa.[1]
Tractolira germonae là một loài ốc biển, là động vật thân mềm chân bụng sống ở biển trong họ Volutidae, họ ốc dừa.
