Micrelenchus sanguineus sanguineus (Gray, 1843). Plate 18, fig. 3; plate 20, fig. 3.
Trochus (Gibbium) sanguineus Gray, Dieffenbach's Travels in N.Z., 2, 238, 1843.
Cantharidus sanguineus (Gray): Suter, Man. N.Z. Moll., 128, 1913, plate 33, fig. 8.
Cantharidus pupillus (“Hutton”); Suter, Man. N.Z. Moll., 126, 1913, plate 33, fig. 7.
Cantharidus oliveri Iredale, Trans. N.Z. Inst., 47, 438, nom. nov. for C. pupillus “Hutton” of Suter, 1913.
Micrelenchus oliveri (Iredale): Finlay, Trans. N.Z. Inst., 57, 370, 1926.
Micrelenchus oliveri (Iredale): Powell, Rec. Auck. Inst. Mus., 3. 138, pl. 11, fig. 8, 1946.
The type is a small turbinate, imperforate shell 7 mm. high, with quite a pronounced peripheral angle. The spiral ribs, seven on the antipenultimate and eight on the penultimate whorl, are flat topped, with narrow interspaces, only faintly if at all moniliform. Eight primary spirals, made somewhat moniliform by the intersection of growth lines, ornament the base; fine secondary threads occupy the interstices between the outer four spirals. The specimen is gummed to a tablet in a tilted position, and as the photograph shows a tilted shell, it is supplemented by a drawing based on a camera lucida sketch of the type.
It is difficult to match the type of sangiuineus exactly among the large series of New Zealand shells examined. It is clearly one of the group which has been known as oliveri Iredale, and not closely related to the shell illustrated as sanguineus by the writer (Trans. Roy. Soc. N.Z., 77, pl. 7, fig. 13) nor to the several named subspecies (caelata, elongata, mortenseni, morioria). It is very close in shape and colouration to specimens of the rather variable North Island oliveri except that none of the latter seen have such a regular alternation of primary and secondary threads on the base. One or more interstitial basal threads may, however, be present on the base of oliveri, and there appears no escape from the use of the name sanguineus for “oliveri.” I am grateful to Mr. A. W. B. Powell, Auckland War Memorial Museum, for confirming my determination of sanguineus after examining the illustrations of the type.
The name sanguineus was used by Suter for specimens of “oliveri.” and the name pupillus “Hutton” for others; these must all now be called sanguineus, with two subspecies, M. s. sanguineus (Northern New Zealand) and M. s. cryptus Powell (East Coast, South Island). Specimens from off Taumaki Island, South Westland, are closer to sanguineus than to cryptus.
The group of benthic forms previously ranked as subspecies of sanguineus may stand as subspecies of Micrelenchus caelatus (Hutton), the name next in seniority. Suter's Cantharidus sanguineus elongatus is based on two specimens from Lyall Bay, only one of which (here designated lectotype) agrees with Suter's dimensions and rough figure (Atlas, pl. 38, fig. 14). In their variable, generally tall, shape, large number of spirals, rounded periphery and in colour pattern, they agree with Tahunanui shells (Trans. Roy. Soc. N.Z., 77, pl. 7, fig. 13) and the name is thus available for the Cook Strait population.
The nomenclatural changes may be summarised as a list (references in brackets are to Powell's checklist in Shellfish N.Z. (ed. 2), 1947).
Micrelenchus sanguineus sanguineus (Gray, 1843) .
Micrelenchus sanguineus cryptus Powell [376.1].
Micrelenchus caelatus caelatus (Hutton) .
Micrelenchus caelatus elongatus (Suter) [368 and 370].
Micrelenchus caelatus bakeri Fleming.
Micrelenchus caelatus morioria Powell .
Micrelenchus caelatus mortenseni (Odhner) .