Kotatea amicispongia gen. et sp. nov.

urn:lsid:zoobank.org:act: 08A5B3CB-0D10-4203-BE1E-8011FC46D45D

Figs 1B, 2A, 5–6, 7A

Diagnosis

Yellow-orange colonies with white polyps, branching lobes, usually growing on a sponge. Collaret and points colourless, composed of slender, warty spindles and thorny clubs. Tentacles contain irregular, warty, scale-like sclerites. Polyp neck contains tuberculate to warty spindles. Polyp mounds contain thorny clubs. Lobe surface contains similar clubs, as well as spiny spindle-like sclerites and radiates. Base surface contains radiates, clubs and spheroids. Lobe and base interior contains spindles and radiates.

Etymology

The species name is a combination of the Latin ‘ amici ’, meaning ‘friend’, and ‘ spongia ’, meaning ‘sponge’, giving roughly ‘friend of the sponge’ and referring to the habit of specimens growing on sponges.

Material examined

Holotype NEW ZEALAND • Northland, Great Exhibition Bay; 34.4650° S, 173.2115° E; depth 140–141 m; 13 Jul. 2009; Oceans Survey 2020 exped.; stn TAN0906/134; NIWA 156312.

Paratypes NEW ZEALAND • 5 specimens (and several small fragments); same collection data as for holotype; NIWA 56152 • 1 specimen; Northland, ~ 8 km SE of Cape Brett; 35.2160° S, 174.4033° E; depth 99– 105 m; 6 Jul. 2009; Oceans Survey 2020 exped.; stn TAN0906/38; NIWA 154129 .

Additional material

NEW ZEALAND – Northland, Great Exhibition Bay • 1 specimen; 34.4398° S, 173.1297° E; depth 110–115 m; 15 Jul. 2009; Oceans Survey 2020 exped.; stn TAN0906/181; NIWA 57129 • 1 specimen; 34.5562° S, 173.1562° E; depth 105–106 m; 12 Jul. 2009; Oceans Survey 2020 exped.; stn TAN0906/126; NIWA 55958 • 2 specimens; 34.5570° S, 173.28533° E; depth 139–141 m; 13 Jul. 2009; Oceans Survey 2020 exped.; stn TAN0906/132; NIWA 154046 .

Description (holotype, NIWA 156312)

Colony form

The holotype is yellow-orange (ethanol-preserved), attached to a sponge fragment, and measures 2 cm tall by 3 cm wide (Fig. 7A). Three primary lobes emerge from a basal stalk, which is ~ 0.5 cm in height, and these each divide into several small lobules. The base of the colony forms a short membrane which partially encrusts the sponge substrate. Polyps grow all over the surface of the colony but are concentrated towards lobe tips and are rare on the basal membrane. Polyps are white, 0.5–1.5 mm tall when expanded, with colourless collaret and points (Fig. 2A).

Sclerites

Points are composed of slender, warty spindles (~ 0.18–0.28 mm long) and thorny clubs distally (~ 0.12– 0.28 mm long) (Fig. 5A–B). Proximally, the spindles become larger and more crescentic (~ 0.12– 0.28 mm long), transitioning into a transverse orientation and merging with the collaret, which is six to ten rows deep (Figs 5A, 6C). The tentacles contain irregular warty, scale-like forms, often slightly to distinctly crescentic (~ 0.08–0.22 mm long) (Fig. 5C). The polyp neck contains some tuberculate to warty spindles (~ 0.08–0.15 mm long) (Fig. 5D). The polyp mounds and the lobe surface both contain clubs with thorny and leaf-like processes (~ 0.06–0.12 mm long and up to ~ 0.06 mm wide) (Fig. 5E–F), but the latter also contains some spiny spindle-like forms and radiates (~ 0.06–0.12 mm long). The surface of the base contains various radiates as well as some clubs and spheroids (~ 0.06–0.12 mm long) (Fig. 6A). The interior of the lobes contains slender spindles (~ 0.1–0.2 mm long) with branching processes and/or complex tubercles, as well as radiates (~ 0.05–0.1 mm long) (Fig. 5G). The interior of the base contains similar sclerites, but the spindles tend to be smaller (~ 0.08–0.14 mm long) and the radiates larger (~ 0.06–0.12 mm long) (Fig. 6B).

Variability

All specimens are very similar, both in colony form and sclerite composition, varying only slightly in colour (note that all specimens are ethanol-preserved), colony size, the extent of the basal membrane (Fig. 7) and in sclerite size ranges, although the latter fell within the ranges described for the holotype in all cases (Figs 5–6).

Comparisons

In growth form and sclerite morphology, K. amicispongia gen. et sp. nov. is most similar to K. aurantiaca gen. et comb. nov. and K. teorowai gen. et sp. nov., and to a lesser extent resembles K. kapotaiora gen. et sp. nov. and K. raekura (in growth form only). Kotatea amicispongia is easily distinguishable from K. lobata gen. et sp. nov., K. kurakootingotingo gen. et sp. nov. and K. niwa gen. et sp. nov. by these species’ more robustly lobed growth forms.

All specimens of Kotatea amicispongia gen. et sp. nov. markedly differ from all specimens of K. aurantiaca gen. et comb. nov. in possessing far larger (and more abundant) clubs in their points (up to 0.28 mm long vs ~ 0.1 mm long, compare Figs 5B and 9B) and much wider polyp mound clubs (up to 0.06 mm vs no more than ~ 0.03 mm, compare Figs 5E and 9E). Additionally, spindles of the collaret and points are overall smaller and more slender in K. amicispongia (compare Figs 5A and 9A), which is particularly apparent when polyp armatures are compared in situ (compare Figs 6C and 10B), as this causes the collaret and points to appear much more crowded with sclerites than the more uniform arrangement typical in K. aurantiaca . Specimens of K. amicispongia also tend to have deeper collarets than those of K. aurantiaca (6–10 vs 4–7 rows), and based on available material K. amicispongia may be restricted to deeper depths (> 100 m vs <100 m).

Other than colour (compare Figs 7A and 24B), a clear difference between K. amicispongia gen. et sp. nov. and K. teorowai gen. et sp. nov. is that specimens of K. amicispongia lack the leafy spheroids that form a distinctive component of the lobe surface in K. teorowai (compare Figs 5F and 27F). The two species are also distinct for their interior sclerites, which are far more abundant and more heavily ornamented in all specimens of K. amicispongia than in K. teorowai, being very rare (and absent towards the base) and sparsely ornamented in the latter (compare Figs 5G, 6B and 27H).

While the sclerites of K. amicispongia gen. et sp. nov. differ markedly from those of K. kapotaiora gen. et sp. nov. and K. raekura gen. et sp. nov. (compare Figs 5–6 with 12–13 and 25–26), specimens of K. kapotaiora can also be easily distinguished by their white colouration and specimens of K. raekura by their orange-coloured collaret and points sclerites. Available material also suggests that K. raekura may be restricted to Manawatāwhi/Three Kings Islands and much shallower depths (collected at <20 m vs> 100 m in K. amicispongia).

Habitat and distribution

All specimens were collected off the east coast of far northern New Zealand, between Great Exhibition Bay and around Cape Brett, at ~ 100–140 m depth (Fig. 1B). NIWA 55958 and NIWA 57129 were collected from rocky sites, and NIWA 56152 from muddy sites. All specimens except NIWA 57129 are attached to sponge fragments, and NIWA 154046 was collected with mostly sponge material. Some of the specimens were collected along with specimens of Ushanaia ferruginea gen. et sp. nov. and the sponge fragment attached to NIWA 154129 is encrusted with small patches of this species.