Axinella badungensis, Alvarez, Belinda, De Voogd, Nicole J. & Soest, Van, 2016

Alvarez, Belinda, De Voogd, Nicole J. & Soest, Van, 2016, Sponges of the family Axinellidae (Porifera: Demospongiae) in Indonesia, Zootaxa 4137 (4), pp. 451-477 : 452-455

Axinella badungensis sp. nov.

( Fig. 1 , 2 )

Material examined. HOLOTYPE.– RMNH POR.5224, Indonesia Bali, NW side of Nusa Penida, Toyapakeh, 8.6822°S, 115.4822°E, 30 m depth, 19 April 2001, #Bal29/NV/ 190401 /229, coll. N.J. de Voogd. PARATYPE.— RMNH POR.10184, Indonesia, Bali, NW side of Nusa Penida, Toyapakeh, 8.6822°S, 115.4822°E, 30 m depth, 19 April 2001, #Bal29/NV/ 190401 /229, coll. N.J. de Voogd. RMNH POR. 5221, Indonesia, Bali, N side of Nusa Penida, off Tukad Adegan, 8.6756°S, 115.5216°E, 30 m depth, 20 April 2001, #Bal32/NV/ 200401 /229, coll. N.J.

de Voogd. ADDITIONAL MATERIAL.— RMNH POR. 3617, Indonesia, Bali, NE side of Nusa Lembongan, Tanjung Jangka ('Jack Point'), 8.6627°S, 115.4683°E 30 m depth, 18 April 2001, #Bal27/NV/ 180401, coll. B.W. Hoeksema.

Description. Shape ( Fig.1 A, C). Flabellate or branching, up to 16 cm high and 20 cm wide, on short and broad peduncle. Branches thick, with rounded, irregular and lumpy margins, becoming wider at distal ends and with furry tips due projection of choanosomal fibres; or folding in irregular shaped tubes.

Colour. Light salmon pink. Beige in alcohol.

Oscula. Uniformly distributed in flabellate specimens, less than 2 mm in diameter, with elevated rims. Less regularly distributed in branching specimens, flushed (i.e. opening at the same level of the sponge surface, not raised or depressed) and sometimes aggregated in groups of 4–5, or on small mounds.

Surface. Transparent skin distinguishable but not easy to peel off in live specimens. Preserved specimens smooth-microconulose; with a furry texture.

Skeleton ( Fig.1 B, D). Ectosomal skeleton not specialised. Choanosomal skeleton plumoreticulated; slightly fascicular and compressed in the axis of the branches/peduncle. Spicule tracts pauci-multispicular, bounded by clear spongin, waving and ascending to surface; becoming thicker and forming thick brushes at subectosomal level with ending of spicules projecting slightly through ectosome. Secondary tracts unispicular-paucispicular, connecting primary tracts, generally one spicule long.

Spicules ( Fig.1 E, Table 1). Styles, thick, slightly curved, sinuous or straight; some with slightly constricted bases, 233–325 x 11.8–19.8 µm. Few oxeas in the same size category. Thinner forms of both styles and oxeas common.

Remarks. The species described here is similar to Axinella sinoxea Alvarez & Hooper, 2009 from northern Australia. Both species are similar in external morphology, skeletal arrangement and size of styles. The megascleres consist mainly of styles; oxeas are very rare, as also reported for other species of Axinella (Alvarez et al. 1998; Alvarez & Hooper 2009). Axinella sinoxea differs from the present species by the presence of characteristic and abundant raphides. Future genetic population studies might be useful to confirm whether or not the occurrence of this spicule type (i.e., raphids) is consistent within and between populations and a reliable diagnostic trait to discriminate species of Axinella .

The species described here also share characteristics of the external morphology and skeletal architecture with Axinella aruensis , in particular with the form II described by Alvarez & Hooper (2009). Nevertheless, the latter differ in size and composition of spicules which consists of oxeas and styles in nearly equal proportions and in smaller size range ( Table 1).

Specimen Locality Styles and less frequent oxeas RMNH POR. 5224 (holotype) Bali 237–308.5µm (270.3±15.8) x 11.8–16.1µm (13.5±1.3)

RMNH POR. 5221 Bali 233–325.8µm (288.7±20.3) x 12.2–19.8µm (16±2.1) Axinella badungensis sp. nov. is also distinguished from other species of Axinella from the Central Indo- Pacific realm (i.e. A. lifouensis, Lévi & Lévi, 1983 , A. loribella Alvarez & Hooper, 2009 , A. plumosa Lévi & Lévi, 1983 , A. retepora ( Lendenfeld, 1887) by external shape, skeletal arrangement, spicule composition and size of spicules: A. lifouensis is thinly flabellated with large oxeas and styles; A. loribella is also thinly flabellated, with a clear axial skeleton and plumoreticulated extra-axial skeleton and with spicules that vary from strongyles to oxeas; A. retepora is better allocated to Echinoclathria (comb.nov., here established; type specimen BMNH 1886.8.27.414 examined); and A. plumosa (fragment of paratype, MNHN LBIM DCL 2974, examined) has only oxeas organised in ascending plumo-echinated and dendritic multispicular tracts.

The material was also compared to other species from the Indian Ocean with skeleton formed mainly by styles: Axinella donnani ( Bowerbank, 1873) and A. aruensis (see Alvarez & Hooper, 2009); A. flabelloreticulata Burton, 1959 and A. ventilabrum Burton, 1959 which have bigger styles; A. massalis Burton, 1959 is massive and has microxeas and thrichodragmata; A. minor Thomas 1981 ,is finger-shaped; A. proliferans Ridley, 1984 , A. tenuidigitata Dendy, 1905 and A. weltnerii ( Lendenfeld, 1897) differ in general habit and skeletal characteristics.

Distribution. Only found in deeper water on the reefs of the islands Nusa Penida and Nusa Lembongan off the southeastern coast off Bali (Lesser Sunda MEOW, Fig. 2 ). Found only at 30 m depth.

Etymology. This species appears to be endemic to the islands Nusa Penida and Nusa Lembongan. The Strait of Badung separates these islands from Bali.

Figures

FIGURE 1. Axinella badungensis sp. nov. RMNH Por. 5224: A, photographed in situ (photo Nicole de Voogd), B, light microphotograph of skeleton. RMNH POR. 10184: C, preserved specimen, D, light microphotograph of skeleton; E, drawing of spicules. Scale bars: C, 4 cm; B, D, 500 µm; E, 50 µm.

FIGURE 2. Map showing the geographical location of the described species.