Novocrania huttoni (Thomson, 1916)

Jeffrey H Robinson, 2017, A review of all Recent species in the genus Novocrania (Craniata, Brachiopoda), Zootaxa 4329 (6), pp. 501-559 : 522-523

Novocrania huttoni (Thomson, 1916)

Stratigraphic range: Late Oligocene–Recent (Robinson in press)

1873: Crania sp. indet. Hutton. Cat. Mar. Moll. N. Z., p. 87.

1906: Crania sp. Hamilton. Bull. Col. Mus., 1, p. 41.

1916: Crania huttoni Thomson, Trans. N. Z. Inst., 48, p. 41, pl. 1, figs. 1–2. 1986: Neocrania huttoni (Thomson), Lee & Brunton, Bull. Nat. Hist. Mus. (Geol.), 40 (4), p. 152. 2001: Novocrania huttoni (Thomson), Lee & Brunton, Bull. Nat. Hist. Mus (Geol.), 57 (1), p. 5.

Synonymy. Hutton (1873) first recorded the presence of Recent Crania in New Zealand. Thomson (1916) described and named the new Recent species C. huttoni from Whangaroa Harbour, Northland (Lee 1987) and described them as having “fine radial ribs”. Bowen (1968) described specimens without radial ribs. Campbell & Fleming (1981) first recorded its presence in the Sounds of Fiordland. Lee and Brunton (1986) placed Crania huttoni in Neocrania . Lee (1987) discussed the morphology, ecology, distribution and variability of Recent Neocrania huttoni in New Zealand. Lee & Brunton (2001) replaced Neocrania with Novocrania .

Localities. Doherty (1976), Lee (1987), Robinson & Lee (2011) and Robinson (2014a) listed 63 localities where N. huttoni has been collected around New Zealand. Previously unpublished localities from New Zealand and Australia are listed herein ( Table 7). Localities are shown in Figure 4 which includes localities of material examined ( Table 7) and published localities (Appendix 5).

Stratigraphic range. Robinson & Lee (2007) noted that fossil N. huttoni of Late Eocene age had been found in North Otago, however, Robinson (in pre ss) assigned that material to N. lecointei . Robinson (in press) illustrated Late Oligocene (Duntroonian, 27.3–25.2 Ma) specimens identified as N. huttoni from Southland, New Zealand.

Ventral valve. Hutton (1873, p. 87) described the ventral valve of this species only as “smooth”. Thomson (1916) did not mention the ventral valve at all. Lee (1987, p. 53) stated that the ventral valve “is a thin, flat, organic membrane with little, if any, calcite present.” Robinson (2014a) assumed this species was like N. lecointei and stated that the ventral valve of N. huttoni had an organic rostellum and posterior adductor pads. However, since that publication I have been able to examine five dried ventral valves with poorly preserved rostella. It appears that the rostellum is composed of a non-crystalline calcareous material.

Type material and type locality. The type material is held in Te Papa Tongarewa, the National Museum of New Zealand ( NMNZ BR.000069). The type locality is Whangaroa Harbour, Northland, New Zealand (Lee 1987).

Material examined. Recent specimens were examined from New Zealand and Australia ( Table 7).

Description. The dorsal valves of N. huttoni are highly variable in outline, from sub-circular to sub-quadrate to having five or six sides to irregular ( Fig. 12A–E ; Lee 1987, figs. 4–7). The dorsal valves vary in profile from being nearly flat to sub-conical ( Fig. 12F ) to strongly conical, the apex is usually in the posterior third of the valve. The posterior margin is straight or slightly curved. The largest specimen examined was 22 mm long, 20 mm wide and 6.6 mm high (Lee 1987, fig. 14). The valve ornament and colour are highly variable. Specimens from Thomson Sound, Doubtful Sound and Bradshaw Sound, Fiordland may be smooth with fine concentric growth lamellae ( Fig. 12A ) or may have discontinuous fine radial riblets ( Fig. 12B, G ). Specimens from the east coast of the North Island have discontinuous fine radial riblets, as originally described by Thomson (1916) for the type specimens. In populations from Three Kings Islands (Lee 1987, fig 5.5) and Northland (Robinson & Lee 2011, fig. 5A–C, E–I) some specimens have developed the radial riblets into tiny spines up to 100 µm long ( Fig. 12C, H ). Fiordland populations may be grey, sometimes with concentric rings of light and dark grey, or mottled brown and white. Populations from East Cape, Northland and Three Kings may be brown or white or mottled brown and white ( Fig. 12E , Ia). The single specimen from off Flinders Island, Tasmania (exterior partly covered in epibionts) is smooth and light brown. Specimens from Lord Howe Island, Australia have a smooth but hummocky surface ( Fig. 12D ) and are various shades of white to greyish-white.

The dorsal interior of N. huttoni ( Fig. 13A–F) is less variable than the exterior ornament. The valve surface is densely punctate. The posterior adductor muscle scars vary in shape from sub-round to sub-oval and lie close to the posterior margin. They may be flush with the valve surface, slightly concave or convex. The anterior adductor slow-muscle scars are reniform to U-shaped with dimples of the anterior adductor quick-muscle scar tucked into the concave side ( Fig. 13C, E). The support structure scars are cresentic in shape and lie laterally of the anterior adductor muscle scars. The small anterior muscle scars are small, sub-oval to teardrop shaped and may be separated and flush with the valve surface ( Fig. 13B, C) or they may be side by side and sometimes on a small raised mound ( Fig. 13D, E), this variation occurs in most populations.

The ventral valve of N. huttoni is an organic membrane overlying a very thin, patchy layer of a non-crystalline calcareous material ( Fig. 12 Ib, Fig. 13G, H, I). The non-crystalline calcareous material layer ranges from extensive ( Fig. 12 Ib) to very little ( Fig. 13I). The rostellum is also composed of the non-crystalline calcareous material overlain by the ventral valve membrane ( Fig. 13J–N) and there appears to be older layers of the ventral valve membrane interlayered within the rostellum ( Fig. 13L, M). The single complete rostellum ( Fig. 13G, J) appears to have dried out and split. Four dried ventral valves have a partial rostellum, the anterior tip and area where the anterior adductors attach are partly preserved ( Fig. 13H, I, K–M).

Ecology. Around New Zealand N. huttoni attaches to the undersides of rocky surfaces, in caves and beneath boulders. It occurs from just below low tide to 400 m (Lee 1987). The Australian specimens were collected at 640 m (off Tasmania) and at 900 m off Lord Howe Island (empty valves picked from shell hash, possibly from shallower water originally).

Remarks. This is the first time that N. huttoni has been recorded from Australia, thus it can no longer be considered an endemic New Zealand species. A specimen figured by Lee (1987, fig. 5.4, AUZ 53) as N. huttoni from 800 m depth off Three Kings Islands, New Zealand was re-examined and is identified as a specimen of Valdiviathyris quenstedti .

The non-crystalline material in the ventral valve fizzed in weak hydrochloric acid and is thus assumed to be at least partly calcareous. Figure 13N shows a fragment of the rostellum with the (dried) overlying ventral valve membrane attached. The non-crystalline material is very fine grained and firm but is scored easily by fine tweezers. The curving fractures ( Fig. 13J, N) suggest that the non-crystalline material is wet when the animals are alive and that it shrinks and cracks when dried.

Figures

FIGURE 4. Localities of Novocrania huttoni (red dots), N. indonesiensis (pink square) and N. roseoradiata (yellow rectangle).

FIGURE 12. NOvOcrania huttOni dorsal valves. A, F. NMNZ BR. 001497 (Doubtful Sound). A. Smooth valve exterior. F. Lateral view. B, G. OU 43710 (Three Kings Islands) B. Valve exterior with fine radial ribs. G. Close-up of radial ribs. C, H. NMNZ BR. 001485 a (Northland). C. Valve exterior with tiny spines in radial rows. H. Close-up of spines. D. NMNZ BR. 001442 a (Lord Howe Island). Hummocky valve exterior. I. OU 44471 a – b (Three Kings Islands). Two specimens (a & b) attached to a cobble, specimen a shows dorsal valve exterior, specimen b shows dried organic ventral valve membrane with most of the rostellum missing and extensive non-crystalline calcitic material beneath valve membrane.