Comprehensive Description

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Description

Calliostoma (Maurea) maui Marshall, new species

 

(figures 63, 70-72)

 

 

Description: Shell up to 44 mm high, broader than high, thin, anomphalous or with a shallow umbilical depression, glossy; spire 1.24-1.59 × higher than aperture, evenly conical, spire angle 73-91°. Protoconch and earliest teleoconch whorls translucent white. Subsequent whorls either pale pink through uniform translucent while outer shell layer or pale buff or pinkish buff with yellowish or reddish brown spiral cords and predominantly white nodules. Protoconch ca. 400 µm wide, surface sculpture worn away in all available specimens. Teleoconch of up to 9 strongly and rather evenly convex whorls, suture well impressed, periphery rounded, base weakly convex. Primary sculpture on spire consisting of spiral cords that multiply by intercalation from 4 (P1-P4) to 7 (P1-P4, S1-S3) or occasionally 6 (S3 absent), up to 3 tertiary spirals occasionally arise on penultimate and last adult whorl, summit of P4 partly covered by succeeding whorls and locally fully exposed. Nodules roundly conical; spiral interspaces considerably broader than each spiral, becoming finely spirally lirate. P1-P4 commencing immediately. P1 at first much weaker than P2 and P3, which are similar throughout, gradually enlarging to resemble them, occasionally weakening and becoming obsolete on last adult whorl. Secondary spirals gradually enlarging to resemble primaries, S1 commencing early to late on 4th whorl, S2 on late 3rd to mid 4th whorl, S3 on mid 4th to early 5th whorl. Base covered with spiral lirae, 2 or 3 nodular spiral cords on innermost part, other basal spiral cords almost or entirely obsolete. Axial costae strong on 1st 3 whorls, obsolete thereafter. Aperture ovate, inner lip thickened, parietal lip very thin, outer lip thin and simple.

 

 

Type Data: Holotype MNZ M. 87449 (height 27.3 mm, width 31.3 mm, 7.1 teleoconch whorls); BS 561, 41°24'S, 174°33'E, Cook Strait, alive, 256-274 m, 29 September 1976, r.v. Acheron. Paratypes (6): 41°35'S, 175°00'E, off Palliser Bay, alive, 256-490 m, 19-20 December 1966, USNS Eltanin stn 1848 (1 USNM); C 703, 42°42'S, 173º37.8'E, off Kaikoura, alive, 180-140 m, 19 June 1961, m.v. Viti (1 NZOI); E 759. 42°45'S, 173°40'E, off Kaikoura, alive, 195-213 m, 31 March 1967, m.v. Viti (1 NZOI); BS 783, 43°31'S, 173°30.5'E, Pegasus Canyon, NE of Banks Peninsula, alive, 256-293 m, 21 February 1979, r.v. Acheron (1 MNZ); 43°56.4'S, 179°25.1'W, W of Chatham Is., alive, 303-296 m, 15 September 1987, f.v. Chiyo Maru 5 (1 MNZ); off North Canterbury, alive, ca 100 m, J. Sutherland (1 MNZ).

 

 

Other Material Examined: 10 specimens MNZ: BS 542, 41°08'S, 174°35.5'E, Cook Strait, subfossil, 282-293 m, 12 March 1976, r.v. Acheron (5); BS 561, 41º24'S, 174°33'E, Cook Strait, subfossil, 256-274 m, 29 September 1976, r.v. Acheron (4); VUZ 99, 41°34.3'S, 174°43.3'E, old shell, 274 m, 29 August 1957.

 

 

Distribution (figure 63): Cook Strait. Chatham Rise, and off north-eastern South Island, living at 140-490 m on rugged substrata.

 

 

Diet: The intestinal tract of the holotype contained mostly fragments of thecate hydroids (Cnidaria), with some indeterminate organic matter.

 

 

Remarks: Calliostoma maui closely resembles lightly built forms of C. simulans and depressed forms of C. blacki from the eastern Chatham Rise in general facies, all three having similar development of teleoconch sculpture, numerous fine spiral lirae on adult teleoconch whorls, and a tendency toward obsolescence of all but the innermost few spiral cords on the base. Calliostoma maui closely resembles C. simulans in having all teleoconch whorls markedly convex and in that P1 at no stage becomes larger or more heavily nodular than the other primary spire spirals as it does in C. blacki. It differs from C. simulans in having considerably finer spiral cords on the spire with finer, mostly more sharply pointed nodules, and in being usually more broadly conical (sa 73°-91°, mean 81°, n = 7; instead of 66°-81º, mean 72°, n = 54). During early stages of the present study I suspected that C. maui might be an extreme phenotypic variant of either C. blacki or C. simulans. Subsequent recognition of a specimen living together with C. blacki and C. simulans in a single sample from off Banks Peninsula (MNZ M.90065, 64651, 64650), however, suggests that another closely related species is involved. Further evidence is suggested by the occurrence in Cook Strait of populations of C. maui that are geographically intermediate between populations of C. simulans (figure 63). Living specimens from Cook Strait, including the holotype (figure 72), are distinctive in having a shallow umbilical depression. Broken, worn, rust-stained specimens from the floor of the Cook Strait Canyon (MNZ M.52531, 54912) are evidently Pleistocene fossils that have been reworked by current scour of soft sediment following breaching of a Cook Strait land bridge, probably after the last glaciation (Fleming, 1951, 1963; Pantin, 1957; Marshall, 1978). They have considerably thicker shells than Recent specimens from Cook Strait but are otherwise identical.

 

 

Etymology: After Maui, the legendary Maori fisherman.

 

 

(Marshall, 1995: 106-108)

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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