Penares mollis, 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 : 12-14

Penares mollis sp. nov.

( Fig. 7–9 ; Table 3 )

Material examined. Holotype — NIWA 101525, NZOI Stn Z15942 , Three Kings Islands, 34.176° S, 172.049° E, 10 m, 24 Feb 2002 . Paratypes — NIWA 101575 (0CDN6636-W) , Three Kings Islands , 34.166° S, 172.150° E, 16– 17 m, 16 Apr 1999 ; NIWA 62287 , 34.418° S, 172.845° E, 18 m, 23 Mar 2007 . Other material. Northland: NIWA 62309 , 34.418° S, 172.845° E, 18 m, 23 Mar 2007 . NIWA 62231 , 34.402° S, 172.991° E, 18 m, 25 Mar 2007 ; NIWA 62409 , 35.831° S, 174.497° E, 25 m, 7 Oct 2004 .

Type locality. Three Kings Islands, New Zealand.

Distribution. Three Kings Islands and Northland, New Zealand ( Figure 9 ). Found growing on rocky substrate in shallow waters (6–28 m).

Description. Morphology is irregularly lobed ( Figure 7 A–C). The holotype is 70 mm × 60 mm × 50 mm high. Surface is very smooth, felty to the touch. Interior is fuzzy. Large uniporal oscules, 2–6 mm in diameter, and smaller uniporal pores, 0.5–0.7 mm in diameter, are sparsely scattered over the sponge, more commonly present on the apex of the lobes ( Figure 7C & D ). Texture is soft, compressible. Colour in life is grey or black, interior is cream. Colour in ethanol is grey brown, interior is beige.

Skeleton. Cortical skeleton is thin (100–200 µm) and consists of a dense layer of disorganised microxeas and microrhabds. Tylasters are scattered throughout the cortex and are more common on the surface of the sponge. Choanosomal skeleton contains a single layer of orthotriaenes that are arranged with their cladome parallel to the cortex/choanosome boundary ( Figure 7E ). Bundles of oxeas are loosely radial near the surface of the sponge but become more disorganised towards the centre of the sponge. Tylasters and microxeas are abundant and scattered throughout the choanosome. Microrhabds are more sparsely scattered throughout the choanosome.

Spicules ( Figure 8 ; Table 3 ). Megascleres —oxeas ( Figure 8A ) are small, slender and straight or slightly curved; 837 (573–1282) × 17 (9–28) µm (n = 74). Orthotriaenes ( Figure 8B ) are short with a relatively long conical rhab- dome. Clads are slightly backwardly curved, and occasionally bifurcate; 380 (184–615) µm long × 350 (175–579) µm wide (n = 73).

Microscleres —microxeas ( Figure 8D ) are relatively stout and often sharply bent rather than gradually curved, very variable in length; 163 (84–356) × 8 (5–13) µm (n = 75). Microrhabds ( Figure 8E ) are small are slightly curved with broadly rounded tips; 60 (30–101) × 5 (3–9) µm (n = 75). Tylasters ( Figure 8C ) are very small with several slender, spined rays. Spines are concentrated around the ray tips; 11 (8–15) µm in diameter (n = 76).

Etymology. Named after the soft, compressible texture of the sponge (mollis, soft; Latin).

Remarks. Penares mollis sp. nov. is very similar to P. tylotaster in spicule complement, the most obvious difference being that P. mollis sp. nov. has slender orthotriaenes while P. tylotaster predominantly has stouter di- chotriaenes. Penares tylotaster does have some plagiotriaenes and triaenes with a mixture of single and bifurcate clads, but dichotriaenes are much more common. The oxeas of P. mollis sp. nov. are also considerably smaller (837 (573–1282) µm) than those of P. tylotaster (1212 (978–1404) µm). All other spicule types and sizes are very similar between the two species. The two species also differ in texture— P. tylotaster is firm and rigid, whereas P. mollis sp. nov. is soft and compressible. Apart from P. mollis sp. nov. and P. tylotaster, no other New Zealand Penares species possesses tylasters.

There are only three other species of Penares described from the South Pacific: P. micraster Lévi, 1993 and P. palmatoclada Lévi, 1993 from New Caledonia, and P. ochracea ( Carter, 1886) from Australia. The presence of tylasters in P. mollis sp. nov. differentiates it from all three South Pacific species. Penares palmatoclada and P. ochracea lack euasters, while P. micraster possesses spherasters.

Figures

FIGURE 7. Penares mollis sp. nov.: A. Holotype NIWA 101525 in situ; B. Paratype NIWA 101575 fresh specimen; C. Para- type NIWA 62287 preserved in ethanol; D. Oscules and pores of NIWA 101575; E. Section showing the crust of microxeas and microrhabds in the cortex and the position of the orthotriaenes directly below the cortex; F. Close view of a choanosome section showing the abundant tylasters.

FIGURE 8. Penares mollis sp. nov., paratype NIWA 101575: A. Oxea; B. Orthotriaene; C. Tylasters; D. Microxeas; E. Microrhabd.

FIGURE 9. Distribution of Penares mollis sp. nov. around New Zealand. The white outline shows New Zealand’s Exclusive Economic Zone.

Tables

TABLE 3. Spicule dimensions (µm) of Penares mollis sp. nov. Dimensions are given as the mean (minimum–maximum) length × mean (minimum–maximum) width (number of spicules measured). OX = oxea; OR= orthotriaene rhabdome, OC = orthotriaene clad; OCC = orthotriaene cladome; MOX = microxea; MR = microrhabd; TYL = tylaster.

Specimen	Megascleres	Microscleres
NIWA 101525	OX: 848 (690–994) × 21 (16–28) (20)	MOX: 154 (84–242) × 7 (5–11) (20)
holotype	OR: 418 (271–549) (20)	MR: 58 (37–97) × 5 (4–7) (20)
	OC: 241 (180–295) (20)	TYL: 11 (8–15) (20)
	OCC: 420 (295–579) (20)
NIWA 101575	OX: 977 (750–1282) × 21 (15–27) (20)	MOX: 146 (90–275) × 9 (6–13) (20)
paratype	OR: 514 (362–615) (20)	MR: 54 (30–85) × 5 (3–7) (20)
	OC: 220 (169–264) (20)	TYL: 11 (8–14) (20)
	OCC: 401 (263–517) (20)
NIWA 62287	OX: 772 (573–929) × 12 (9–15) (20)	MOX: 162 (110–287) × 7 (5–9) (20)
paratype	OR: 247 (184–323) (21)	MR: 69 (36–100) × 5 (3–8) (20)
	OC: 140 (96–186) (22)	TYL: 11 (8–13) (21)
OCC: 257 (175–332) (20)