Penares kermadecensis, Sim-Smith & Kelly, 2019

Sim-Smith, Carina & Kelly, Michelle, 2019, Review of the sponge genus Penares (Demospongiae, Tetractinellida, Astrophorina) in the New Zealand EEZ, with descriptions of new species, Zootaxa 4638 (1), pp. 1-56 : 24-25

Penares kermadecensis sp. nov.

( Fig. 17–19 ; Table 6)

Material examined. Holotype — NIWA 76259, NIWA Stn TAN0413/137, Southern Kermadec Ridge, 37.331° S, 177.075° E, 375–414 m, 14 Nov 2004. Paratypes — NIWA 76261, NIWA Stn TAN0413/128, Southern Kermadec Ridge, 37.329° S, 177.073° E, 358–380 m, 14 Nov 2004.

Type locality. Southern Kermadec Ridge, New Zealand.

Distribution. Only known from the type locality, Southern Kermadec Ridge, New Zealand ( Figure 19 ). Grows on hard substrate, 358–414 m.

Description. Holotype is a thinly encrusting sponge growing on coral rubble and gravel ( Figure 17A ), while the paratype NIWA 76261 is a small, branching sponge ( Figure 17B ). The holotype is 25 mm × 15 mm ( Figure 17A ). Texture is very hard, barely compressible. Surface is wrinkled and sculptured, slightly scratchy to the touch. No oscules or pores are visible. Colour in ethanol is light beige to orange brown.

Skeleton. Cortical skeleton is thin (80–500 µm) and consists of densely packed, tangential microxeas ( Figure 17D & E ). Choanosomal skeleton has a single layer of dichotriaenes present just below the cortex, arranged with their cladomes uppermost ( Figure 17C ). Oxeas are abundant in the choanosome. In places, bundles of tangential oxeas are present near the surface ( Figure 17D ). Microxeas are abundantly scattered throughout the choanosome Spicules ( Fig. 18 ; Table 6). Megascleres —oxeas ( Figure 18A ) are small, slender and almost straight to angulate with bluntly rounded or slightly pointed tips; 815 (562–1107) × 22 (13–33) µm (n = 40). Dichotriaenes ( Figure 18B ) have an extremely short rhabdome and long stout clads with sharply pointed tips. Some clads are trifurcate ( Figure 18C ); 197 (122–300) µm long × 854 (644–1085) µm wide (n = 30) Microscleres —microxeas ( Figure 18D ) are short, stout and straight or curved with sharply pointed tips. Microxea size is quite variable; 114 (34–220) × 9 (4–17) µm (n = 80).

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Etymology. Named for the type locality and known distribution of this species, the Kermadec Ridge.

Remarks. Penares kermadecensis sp. nov. is the only New Zealand Penares species that lacks euasters. The spicule complement and dimensions of P. kermadecensis sp. nov. are very similar to those of P. schulzei , with the exception that P. schulzei possesses oxyasters. The most pronounced differences between the two species are mor-phology— Penares kermadecensis is a thinly encrusting or small, branched, orange brown sponge when preserved, whereas P. schulzei is purple when preserved, massive in form, and its choanosome is filled with boring gastropods and debris.

Two South Pacific species, P. palmatoclada and P. ochracea also lack euasters. However, P. palmatoclada has much larger oxeas (3000–4000 µm) than P. kermadecensis sp. nov. (815 (562–1107) µm), and P. ochracea possesses both microxeas and microrhabds, while P. kermadecensis sp. nov. only possesses microxeas.

Figures

FIGURE 17. Penares kermadecensis sp. nov.: A. Holotype NIWA 76259 preserved in ethanol; B. Paratype NIWA 76261 preserved in ethanol; C. Close up view of the surface of paratype NIWA 76261 showing triaene cladomes that lie just below the surface of the sponge; D. Thin section of NIWA 76261 showing the position of the dichotriaenes under the cortex and the tangential bundles of oxeas in the choanosome; E. Cortical section of NIWA 76261 showing the tangential layer of microxeas at the surface.

FIGURE 18. Penares kermadecensis sp. nov.: A. Oxea; B. Dichotriaenes; C. Dichotriaene with a trifurcate clad; D. Microxeas. All spicule images are from holotype NIWA 76259 except for the smallest microrhabd, which is from paratype NIWA 76261.

FIGURE 19. Distribution of P. kermadecensis sp. nov. around New Zealand. The white outline shows New Zealand’s Exclusive Economic Zone.