Spondylus groschi Lamprell & Kilburn, 1995
LAMPRELL, K. L. & R. N. KILBURN. 1995. The recent Spondylidae of South Africa and Mozambique, with the description of a new species (Mollusca, Bivalvia, Pectinoida). Molluscan Research, 16: 81-95, figs. 1-4. [p. 83, figs. 1A-1C]
1995 Spondylus groschi Lamprell & Kilburn, 1995
K. L. Lamprell & R. N. Kilburn, 1995, figure 1.
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«Diagnosis: Shell ovate, thick. Hinge typical for genus. Top (left) valve moderately and evenly convex; interior slightly excavated under hinge plate, with a strong, coloured crenulated margin; auricles moderately wide, umbonal margins denticulate. Sculpture consisting of 6-7 well-defined, principal radial ribs, bearing strong, depressed, overlapping, spatulate spines which are hollowed on their underside, only slightly narrower at their base, moderately concave at their termination, almost obsolete umbonally; young specimens often develop palmate ends to spatulate spines near lower margin. Each rib interval usual\y with one secondary radial rib ornamented with sharp or slightly flattened, overlapping spines, the remaining interstitial surface covered with dense radial striae and fine, fairly sharp spines. varying in length; however (rarely) in some young specimens the interstitial ornamentation is of equal strength to the principal ribs. Lower (right) valve more convex than top valve. some senile specimens much more convex than younger specimens; cardinal area triangular and shallow; internally with moderate, shallow excavation under hinge plate and a strong, coloured, crenulated margin. Fixation area small, sometimes with a variable amount of thin concentric foliations umbonal\y; sculpture on non-attached part similar to that of top valve. Colour mauve-brown with white at base of spines, or orange, orange red or deep brick-red, main spines sometimes contrastingly yellowish or lilac-coloured; umbonal region often with irregular brown spots, blotches or undulating marks; internally white, with the margins coloured the same as the external surface.
Type locality: SE Conducia Bay. Mozambique.
Material examined: Holotype: 1pv. NM-H164/T1000. SE Conducia Bay, north of Inhaca, Mozambique Province, E side of reef, edge of rock, current, LST, K. Grosch. Nov 1967.
Paratypes: Northern Mozambique: 1pv. NM-H161/T1001, Mozambique Island, south shore, on outer edge. rocky ledge above coral area, LST, K. Grosch, Nov 1958; 1pv, NM-H 166/T1002, Conducia Bay, Mozambique Province, K. Grosch, Nov 1975; 1pv, QM MO52425, south east Memba Bay, south west of Ponta Nangata, Mozambique Province, on rock near coral area, some surf, LST, K. Grosch, Nov 1975; 1pv, NM-H159/T1003, SW Conducia Bay, north of Chocas, Mozambique Province, washed up during cyclone, K. Grosch, Dec 1951; 1pv, NM-H167/T1004, SE Lunga Bay, Mozambique Province, on rock near coral reef, current, some surf, LST, K. Grosch, Sept 1975; 1pv, NM-H163/T1005, Conducia Bay, Mozambique Province, K. Grosch, Sept 1975.
Other material: Northern Mozambique: 1pv, NM-H168, SW Conducia Bay, W of Is. Inhaca Grande, on underside of rock slab in tidal pool, LST, K. Grosch, Oct 1968; 1pv, NM-H171, SW Conducia Bay, NW of Chocas, on edge of rocky shelf, no surf, 0.7 m below LST, K. Grosch, Apr 1961; 1pv, NM-H172, SE Conducia Bay, W. coast of Is. Inhaca Grande, on encrusted rock in tidal pool, LST, K. Grosch, Oct 1968; 1pv, NMH170, SW Conducia Bay, N of Chocas, washed up during cyclone, K. Grosch, Apr 1954; 1pv, NM-H169 SW Conducia Bay, NW of Chocas, on rocky reef, 0.7 m below LST, K. Grosch, Sept 1962; 1pv, NM-H162, Conducia Bay, K. Grosch; 1pv, NM-H165, SE Nacala Bay, E of Fern Velosa, edge of rock above coral area, some surf, LST level, K. Grosch, Jan 1958; 1pv, NM-H160, SE Memba Bay, SW of Ponta Nangata, on rock near coral area, some surf, LST, K. Grosch, Jun 1960. South Africa: Zululand: 1lv, NM-D5195, Sodwana Bay, Two-Mile Reef, 10-15m, dived, D. Herbert, Oct 1986; 1lv, NM-D5096, Sodwana Bay, Two-Mile Reef, outer edge, 14-17 m, dived, D. Herbert, Oct 1986; 2lv, NM-E809, Sodwana Bay, sponge reef, 33 m, dived, D. Herbert & NPB, Sept 1987; 1lv, NM-D1846, Sodwana Bay, Two-Mile Reef, 10-15 m, dived, D. Herbert, Oct 1985; Ipv, NM-E2472, Leadsman Shoal, Raggie Reef, 1-2 km N of Leven Point, 8-12 m, mixed algal and coral reef, dived, D. Herbert & NPB, May 1988; 1lv, NM-E2421, Leadsman Shoal, reef off wreck of Tamavo, 20-28 m, D. Herbert & NPB, May 1988; 1lv, NM-S1038, Kosi Bay, main reef, 1-4 km S of estuary mouth, 18-20 m, dived, D. Herbert & NPB, May 1990; 1Iv, NM-4599, Bhanga Nek, c. 15 km S. of Kosi Bay, beach-drift, O. Bourquin, Jan 1965; 1pv, NM-S1785, between Bhanga Nek and Kosi Bay, reef off marker 13 north, 8-14 m, D. Herbert & NPB, May 1990; 1lv, NM-D9594, between Bhanga Nek and Kosi Bay, No.13 reef, 6-18 m, 12-20 Jul 1987, D. Herbert et al. 1lv, NM-E365I, off Gypsy Hill, Zululand, 65-70 m, NMDP. East Africa: Mombasa, Kenya: 1pv, KL, on reef low tide, 1993.
Measurements of holotype (excluding spines): Height 77.5 mm (umbo to margin), length 77.4 mm, depth (conjoined valves) 44.5 mm.
Measurements of paratypes: NM-H161/Tl001, height 58 mm (umbo to margin), length 64.4 mm, depth (conjoined valves) 35.7 mm; NM-H166/T1002, height 43.5 mm (umbo to margin), length 45.7 mm, depth (conjoined valves) 26.1 mm; NM-H159/T1003, height 50.8 mm (umbo to margin), length 54 mm, depth (conjoined valves) 31.8 mm; NM-H167/T1004, height 35.5 mm (umbo to margin), length 34.4 mm, depth (conjoined valves) 20.9 mm; NM-H163/T1005, height 67.8 mm (umbo to margin), length 70 mm, depth (conjoined valves) 44.6 mm.
Distribution: Zululand (Leadsman Shoal) to Mombasa, Kenya, East Africa.
Habitat: In coral reef areas, attached to rocks or corals, in more tropical areas from low tide (occasionally in pools) to <1m below, further south in about 8-28 m depth.
Remarks: The species is generally constant in its sculpture, although paratype NM-H166, which is slightly juvenile, is more densely spined than normal and has more numerous principal ribs, each of which is ornamented with spatulate spines which are wider at their termination. Some NM lots consist of beach-worn specimens, which have a similar rib count to the holotype, but display variation in shape from ovate or elongate-ovate to moderately fan-shaped.
Comparisons: Spondylus groschi resembles a number of species from the central IndoWest Pacific. It is closest in characters to Spondylus violascens Lamarck, 1819, which differs in having irregular ornamentation, lack of denticulate umbonal margins and narrower interstices that lack the dense spines of this species. S. barbatus Reeve, 1856, differs from S. groschi in possessing both sharp and spatulate spines, intermixed, on the principal ribs; of these the spatulate spines are mainly developed at the lower margins, while the interstices have sharp, short, upright spines; in addition, in S. barbatus the upper margins have colour bars which form a chevron pattern. S. groschi differs from S. squamosus Schreibers, 1793, principally in its having constant black and white radial rays, the presence of colour bars at the upper margins Hnd the lack of denticulations to the margins. S. sinensis Schreibers, 1793, although similar in shape to S. groschi, differs in its greater inflation, longer principal spines, claw-like spatulae, much stronger interstitial ribs and much finer interstitial ornamentation. S. imbutus Reeve, 1856 (= S. nux Reeve, 1856), from the Philippines, differs from S. groschi in having 5 principal ribs which bear sparse, long, strongly incurved. leaf-shaped, fragile spatulae; the interstices bear fine minor ribs with microscopic striae, the auricles are narrow and devoid of denticulations.
Etymology: Named after Kurt Joachim Grosch (1912-1991), veteran Mozambique collector who provided most of the specimens used in this study.»
KEVIN L. LAMPRELL & RICHARD NEIL KILBURN, 1995
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