Hincksina elephantina Reverter-Gil & Souto 2023, sp. nov.

Hincksina elephantina sp. nov.

urn:lsid:zoobank.org:act: FA2C930A-4990-4C55-B8B0-AD31A3E71D03

Figs 7, 12B; Table 5

Hincksina flustroides – López de la Cuadra & García Gómez 1988: 23; 1994: 110 (part or whole). — López de la Cuadra 1991: 94 (part or whole), pl. 7 figs c–d.

Differential diagnosis

Hincksina with 12 thick marginal spines that increase in size distally and a pair of thick oral spines, long and gently curved, resembling elephant tusks. Together, the four distal spines give the autozooid a characteristic appearance. Interzooidal avicularia abundant, with an oval mandible directed distally, usually present in dense clumps. Ovicell endozooidal in distal avicularium or autozooid; proximal margin of ooecium raised centrally, producing a developed central peak.

Etymology

The term ' elephantina ’ alludes to the appearance of the two oral spines in this species, which are thick, long and gently curved, resembling elephant tusks.

Material examined

Holotype STRAIT OF GIBRALTAR • 1 ovicelled colony, coated; Andalucía, La Línea; 36.18167° N, 05.33333° W; depth 30–50 m; May 1985; López-Fé leg.; MHNUSC 10127 (Fig. 7).

Description

Colony encrusting, multiserial, unilaminar. Autozooids elongate oval, arranged in irregular series, separated by shallow grooves. Gymnocyst reduced to the proximal region, cryptocyst a narrow band with a coarse nodular surface, opesia extensive. Vertical walls with two or more uniporous pore plates per neighbouring zooid. A pair of long oral spines, thick and gently curved, resembling elephant tusks. Frontal membrane overarched by 12 (occasionally more) cylindrical mural spines, thick, tapering towards the uncalcified tip. Spines more or less folded over the frontal membrane, sometimes overlapping in the midline. Generally, the first pair is longer and more vertical but converging medially, while the height of the spines decreases proximally, the most proximal spines being the shortest. Spines apparently unjointed at their base. Avicularia interzooidal, rectangular or square in outline, distal to many zooids; usually pointing distally next to autozooids and laterally or distolaterally in ovicelled zooids; rostrum semielliptical, at an acute angle to colony surface, mandible hinged on a pair of short triangular condyles delimiting an approximately semicircular proximal area distinctly wider than long. In concavities or convexities of the substrate, avicularia tend to form irregular clusters. Ovicell endozooidal in distal avicularium or less frequently in the distal autozooid; ooecium continuous with the gymnocyst of the avicularia or autozooid, forming a broad hemispherical cap; proximal margin raised centrally, producing a developed central peak. Ancestrula not observed.

Remarks

Material here described as H. elephantina sp. nov. was originaly reported as H. flustroides by López de la Cuadra & García Gómez (1988, 1994) and López de la Cuadra (1991). However, H. elephantina clearly differs from this and other Iberian species of the genus by several characters:

The two oral spines are thick, long, and gently curved, resembling elephant tusks, while the first pair of the lateral spines is also very developed but shorter, curved and converging medially. Taken together, these spines give a characteristic appearance to the oral end of the autozooid (Fig. 7A–C). Moreover, the remaining spines are also stout, cylindrical and thinner at the tip, covering the opesia but not fusing along the medial line. The average number of marginal spines is 12 (Fig. 7A–C). The quadrangular avicularia are abundant, as in other species such as H. synchysia or H. chimaera sp. nov. (see below), but with a semielliptical rostrum distally directed. Moreover sometimes they appear in clusters, a character not seen in other Hincksina (Fig. 7D–F). Finally, the ovicell of H. elephantina sp. nov. can be immersed in an autozooid or in an avicularium (Fig. 7G), a character that Berning et al. (2021) considered exclusive of H. synchysia, but which is also present in H. chimaera (see below). The ovicell of H. elephantina, however, presents a developed central peak (Fig. 7G), which is characteristic of H. flustroides according to Berning et al. (2021).

At present, H. elephantina sp. nov. is known only from La Línea, Andalucía (Strait of Gibraltar area), collected at 30–50 m depth (Fig. 12B). López de la Cuadra & García Gómez (1988) and López de la Cuadra (1991) reported two colonies of H. flustroides from this locality, but only one is now preserved, here designated as the holotype of the species (MHNUSC 10127). López de la Cuadra (1991) also reported this species from Tarifa at 50–60 m depth, but as the original colony was not preserved we cannot be certain about its identity.