Novocrania roSeoradiata (Jackson, 1952)

Jeffrey H Robinson, 2017, A review of all Recent species in the genus Novocrania (Craniata, Brachiopoda), Zootaxa 4329 (6), pp. 501-559 : 529-530

Novocrania roSeoradiata (Jackson, 1952)

Stratigraphic range: Recent

1952: Crania roseoradiata Jackson. Annals of the South African Museum, 41, p. 7, figs. 1–4.

1986: Neocrania roseoradiata (Jackson), Lee & Brunton, Bull. Nat. His. M. (Geol.), 40 (4), p. 152. 2001: Novocrania roseoradiata (Jackson), Lee & Brunton, Bull. Nat. Hist. Mus. (Geol.), 57 (1), p. 5.

Synonymy. Jackson (1952) described C. roseoradiata from dorsal valves collected in the Saldana Bay, South Africa ( Fig. 4 ). Hiller (1991, table 1; 1994, table 1) listed a single locality for Neocrania roseoradiata . Bitner & Logan (2016) identified one dorsal valve from off Madagascar as Novocrania roseoradiata , however, the valve interior has raised anterior adductor muscle scars and a median process and appears to be N. turbinata . Bitner & Logan (2016) identified two further specimens as Novocrania sp. These dorsal valves have muscle scars flush with the valve floor and one has a hummocky exterior. This study suggests these specimens are more likely to be N. roseoradiata as described by Jackson (1952, p. 8) with “the anterior adductors very distinct in ovate pits”, but their exterior colour was not described.

Type material and type locality. Jackson (1952, figs. 1–4) figured four ‘syntypes’ rather than a single holotype. The type locality is Saldana Bay, north of Cape Town, South Africa, ~ 33.12°S, ~ 17.86°E. The complete dorsal valve SAM-MB-A5665b (Jackson 1952, fig. 2; Fig. 13A, D) is here designated as the lectotype.

Material examined. Images of specimens SAM-MB-A5665a-g of Novocrania roseoradiata , all dorsal valves, were provided by Albe Boseman of the Iziko Museum , Cape Town ( Table 7). These included images of the four syntypes figured in Jackson (1952, figs. 1–4). Three specimens are complete valves and four are partial valves.

Description. The dorsal valves are laterally sub-oval to sub-rectangular in outline, wider than long. The largest is 10 mm long and 12 mm wide ( Fig. 16A ). The posterior margin is wide. The exterior surface has concentric growth lines and is hummocky but no spines or ribs are visible in the images, and none were described by Jackson (1952). The valves are white with reddish-brown colour patches formed by very fine radiating lines of colour in the valve ( Fig. 16A–C ). In the few specimens known the amount of colour varies from covering about half the valve exterior to almost none.

The posterior adductor muscle scars are relatively small and sub-oval. The anterior adductor slow-muscle scars are convex and vary from U-shaped ( Fig. 16D, E ) to reniform ( Fig. 16F–I ) with a deep dimple for the quick-muscle scar. The support structure scars are variably shaped and attached to the adductor scars. The small anterior muscle scars are separated.

Ecology. N. roseoradiata was dredged from 82 metres (Jackson 1952), Hiller (1991) listed N. roseoradiata as being a shallow water form.

Remarks. Only dorsal valves are known for this species; without examining ventral valves it is uncertain if N. roseoradiata is a synonym of N. huttoni or a separate species. Based on these few specimens, the only morphological feature that might separate them from N. huttoni is that the colour patches on N. huttoni valve are ‘solid blocks’ of colour while in N. roseoradiata the colour patches are formed of fine radiating lines of colour. The significance of this difference, and the amount of variation of this feature that may be present within N. roseoradiata , are unknown. The species N. roseoradiata is retained until more material is available.

Some other craniid specimens have been found around southern Africa. Jackson (1952) noted that Turton (1932) had figured a poor specimen from Port Alfred that Jackson had “tentatively” referred to Crania . Hiller (1986) described a single damaged specimen (SAM-A25445) from shallow-water north of East London, SA, as Crania sp., attached to the shell of a Mergerlia. The Iziko Muzeum kindly provided images of this specimen. The valves are small (3 mm by 4 mm) and very thin and show no internal features such as muscle scars or punctae, unlike similar sized craniid specimens figured herein. I suggest specimen SAM-A25445 is not a craniid.

SAM—the Iziko South African Museum , Cape Town, South Africa ; ZMUC—Zoology Museum, Copenhagen, Denmark. Abbreviations: aaq —anterior adductor quick-muscle scar, aas —anterior adductor slow-muscle scar, oi —oblique internal muscle scars, pa —posterior adductor muscle scar, ss —support structure scar.

Figures

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

FIGURE 16. NOvOcrania rOseOradiata dorsal valve (syntypes, Saldana Bay, South Africa). A, D, E. SAM-MB-A 5665 b. A. Valve exterior with radial lines of colour. D. Valve interior with U-shaped anterior adductor slow-muscle scars. E. Line drawing of muscle scars. B. SAM-MB-A 5665 a. Valve exterior with radial lines of colour. C. H, I. SAM-MB-A 5665 c. C. Partial dorsal valve exterior with minimal colour. H. Valve interior. I. Line drawing of muscle scars. F, G. SAM-MB-A 5665 f. F. Partial valve interior. G. Line drawing of muscle scars. NOvOcrania indOnesiensis dorsal valve. J – L. ZMUC-Bra- 20 (holotype, Coral Sea). J. Hummocky valve exterior with mottled colouring. K. Valve interior with small muscle scars. L. Line drawing of muscle scars.