Hillerella Simon, Logan & Mottequin

Simon, Eric, Logan, Alan, Zuschin, Martin, Mainguy, Jerome & Mottequin, Bernard, 2016, Lenticellaria and Hillerella, new kraussinoid genera (Kraussinoidea, Brachiopoda) from Indo-Pacific and Red Sea waters: evolution in the subfamily Megerliinae, Zootaxa 4137 (1), pp. 1-34 : 25

Genus Hillerella Simon, Logan & Mottequin gen. nov.

Type species Hillerella bisepta Simon, Logan & Mottequin sp. nov.

Etymology. Named for Norton Hiller in recognition of his important studies on Recent kraussinoid brachiopods.

Diagnosis. Micromorphic kraussinoid, wider than long, biconvex, tuberculate radial costae mainly on ventral valve; dorsal valve with less prominent costae; ventral valve interior with single central septum, dorsal valve without cardinal process or crura; floor of dorsal valve interior with two prominent subparallel septa directed posteriorly from loop towards the hinge line; loop consisting of an arch supported by two slightly divergent plates attached to valve floor.

Diagnose. Brachiopode kraussinoïde micro-morphique, plus large que long, biconvexe; valve ventrale avec côtes radiales tuberculées; valve dorsale avec côtes moins proéminentes; valve ventrale avec septum central; valve dorsale sans processus cardinal ni crura; surface interne de la valve dorsale avec deux septa subparallèles proéminents dirigés postérieurement du brachidium jusqu’à la charnière; brachidium consistant en une arche supportée par deux plaques divergentes attachées à la surface interne de la valve.

PLATE 11. Lenticellaria marerubris sp. nov. Material collected from the Red Sea, Gulf of Akaba, Dahab, by Martin Zuschin (NHMW) at a depth of 12 m. Size of the specimens indicated with scale bars.

Fig. 1. Holotype. Articulated fully adult specimen opened for this study in order to illustrate the brachidium (NHMW 87192/ GP 247). 1a: dorsal view showing the smooth dorsal valve with concentric growth lines and the wide amphithyrid foramen. This specimen is not distorted and has a nearly semicircular outline. 1b: ventral view showing the tuberculated surface of the ventral valve. Radial rows of tubercles are clearly visible and between these rows an ornamentation made of many concentric lines of very small scales. 1c: detailed view of the tubercles and scales of the same ventral valve. 1d: lateral view. The beak is erect. The lateral commissure is sinuous. In this position the pointed tubercles and the scaly surface of the ventral valve are clearly visible. 1e: detailed view of the lateral view. 1f: anterior view. Anterior commissure is rectimarginate in this specimen. 1g: posterior view. The strong convexity of the dorsal side of the foramen is typical for all specimens investigated. 1h: ventral view of the tuberculate dorsal valve showing the brachidium developing two claws supported by a pedestal. Short crura are visible. 1i: internal anterior view of the dorsal valve showing the high pedestal, the two slender claws and the short crura. The crura are not supported by crural plates or thick crural ridges. 1j: oblique lateral view. 1k: oblique antero-lateral view. 1l: detailed view of the short crura.

Fig. 2. Paratype. Articulated fully adult specimen presented for illustrating the possibility of dorso-biconvex shell and distortion. (NHMW 87192/GP 248). 2a: dorsal view showing smooth dorsal valve and large amphithyrid foramen. Note the cordate outline for this specimen. 2b: ventral view showing the radial rows of tubercles and the scaly surface of the valve. 2c: lateral view showing the sinuous lateral commissure, the convex dorsal of the foramen and the spiny surface of the ventral valve. 2d: anterior view. 2e: posterior view.

Fig. 3. Paratype. Articulated fully adult specimen used for illustrating a strongly distorted shell (NHMW 87192/GP 249). 3a: internal view of the tuberculate dorsal valve with brachidium. 3b: detailed view of the external ventral valve ornamentation. 3c: detail ventral view of the brachidium with its pedestal.3d: anterior view of the two claws of the brachidium. 3e: detailed view of crura.

Fig. 4. Paratype. Articulated fully adult specimen used for illustrating the details of the ventral valve ornamentation. (NHMW 87192/GP 250). 4a: detailed view of the spiny tubercles and of the very small scales on the surface.

Fig. 5. Paratype (NHMW 87192/GP 251). Articulated early juvenile specimen illustrating the ontogeny for this species. 5a: internal view of the dorsal valve with the brachidium at early cucullate phase of development. The crura are just beginning to emerge. The commissural tuberculation of the valve is still reduced. 5b: detailed view of the ventral valve ornamentation. The rows of tubercles and the scaly surface are already developed. 5c: detailed ventral view of the brachidium. Note that the pedestal is already developed. 5d: anterior view of the brachidium. 5e: oblique lateral view of the brachidium. 5f: detailed view of a crus in development (arrows).

Fig. 6. Paratype. Articulated juvenile specimen illustrating later stage of the ontogeny (NHMW 87192/GP 252). 6a: internal view of the dorsal valve with the brachidium at a second stage of development. The resorption process of the posterior part of the cucullate structure is completed and claws in their first appearance are produced. 6b: detailed view of the ventral ornamentation. 6c: detailed anterior view of the brachidium. 6d: detailed posterior view of the brachidium showing the resorption process when completed.