Heterorotula multidentata (Weltnerı 1895)

Pronzato, Roberto & Manconi, Renata, 2019, An overview on the freshwater sponge fauna (Demospongiae: Spongillida) of New Zealand and New Caledonia with new insights into Heterorotula from deep thermal vents of the Lake Taupo, Journal of Natural History 53 (35), pp. 2207-2229 : 2207-2229

Heterorotula multidentata (Weltnerı 1895)

( Figures 1 (B)ı 4(B))

Tubella multidentata Weltnerı 1895 ; Spongilla lacustris var. sphaerica von Lendenfeldı 1887 ; Ephydatia multidentata Weltnerı 1895 ; Rützlerı 1968 (figs. 10 – 12ı p. 63); Ephydatia lendenfeldi Traxlerı 1896 ; Heterorotula multidentata Penney and Racekı 1968 ; Volkmer- Ribeiro and Rützlerı 1997; Manconi and Pronzatoı 2002; Manconi et al. ı 2016; van Soest et al. ı 2018

Comparative materials

BMNH 1890.1.9.339ı holotypeı Heterorotula capewelli type species of the genus Heterorotula . WAM Z27997 ı FW-POR 881 ı Heterorotula multiformis . WAM Z98316ı FW- POR 883 ı Heterorotula cf . multidentata. Type material ( ZMB) of Heterorotula multidentata not examined .

Description (emended after Penney and Racek 1968; Rützler 1968)

Growth form cushion-like (0.5 cm 3) smallı irreguları on dead plant stems. Oscula and inhalant apertures not visible. Consistency very softı compressible. Colour dark grey (alcohol). Skeleton as polygonal meshwork of primary spicuları ascendingı paucispicular (2 – 5 spicules) tracts 100 – 200 µm apart. Megascleres oxeas distinctly fusiformı longı rather slender (280 – 320 × 10 – 18 µm)ı mostly microspiny. Gemmules 490 – 585 µm in diameter. Gemmulosclere birotules of two length classes (32 – 48 µm; 64 – 84 µm) with stout spiny shafts (4 – 6 µm in thickness)ı and exclusively subequal rotules (17 – 22 µm in diameter). Margins of rotules notably indented. Aberrant gemmuloscleres also present (no drawings in the original descriptions).

Habitat

Sponges have been discovered in minute quantitiesı growing on dead plant stems on the tree-shaded river bed (2 – 5 m wide; water temperature 16.10 °C; modified after Rützler 1968).

Geographic range

River La Farino near Col d ’ Amieuı between La Foa and Canala (central South New Caledoniaı 28.VII. 1965ı coll. Dr. Ferdinand Starmuhlner from the Zoologisches Institut der Universität Wien). H. multidentata is the only species shared between New Caledonia and East Australia. The existence of a single Neotropical speciesı Heterorotula fistula ı described by Volkmer-Ribeiro and Motta (1995) from Brazil suggests a Gondwanan track.

Remarks

The status of Heterorotula multidentata is thoroughly discussed by Penney and Racek (1968 ı p. 101; van Soest et al. 2018). It is widespread in Eastern Australiaı rarely penetrating the Dividing Range westward. Species-specific traits are not well definedı not even in the subsequent synopsis of Australian freshwater sponges by Racek (1969) ı which reported megascleres as relatively long and thick smooth oxeası and very large gemmules extremely abundant and freely scattered throughout the skeletal meshwork in large fully mature specimens of H. multidentata always with bulbous growth form. Regarding the New Caledonian specimensı Rützler (1968) stated ‘ Dr. A. Racek (personal communication) suggests that it might be placed between Ephydatia multidentata and E. nigra butı because of the small amount of material and the little significance of spicule sizeı it is considered preferable to refer the specimen to E. multidentata’. Integrative taxonomy with also molecular analyses is necessary.

Figures

Figure 1. (A) Study area of Spongillida (Porifera, Demospongiae) in insular freshwater of Australasia. (B) New Caledonia Island harbours three endemic species viz. Heterorotula caledonensisı Oncosclera diahoti, and Pachyrotula raceki (genus Pachyrotula is also endemic). Heterorotula multidentata is shared by New Caledonia and Eastern Australia. (C) Geographic range of Heterorotula kakahuensis endemic to New Zealand.