Mycale (Arenochalina) aff. tenuispiculata ( Dendy, 1905 ) Van & Aryasari & De, 2021

Van, Rob W. M., Aryasari, Ratih & De, Nicole J., 2021, Mycale species of the tropical Indo-West Pacific (Porifera, Demospongiae, Poecilosclerida), Zootaxa 4912 (1), pp. 1-212 : 47-51

Mycale (Arenochalina) aff. tenuispiculata ( Dendy, 1905) comb.nov.

Figs 29 a–f, 30a–d, 31a–g

Esperella tenuispiculata Dendy, 1905: 161 .

? Parisociella anomala ; sensu Burton 1952: 169 (not: Ridley & Dendy 1886: 341).

Desmacella spec. Erhardt & Baensch 2000: 64.

Material examined. ZMA Por. 14598, Oman, Ras al Khayran , 23.5315°N 58.7408°E, depth 12 m , on fish cage, SCUBA, coll. R. Gomez, SYMBIOSPONGE project, field nr. 98 / IO / NOV05 /RG/002, 5 November 1998 (live color red) ; ZMA Por. 16926, Jordan, Northern Gulf of Aqaba, in front of Marine Science Station , 29.5167°N 35.0°E, overgrowing dead Acropora at depth of 10 m , SCUBA, coll. I. K̂tter, field nr. 538, 2001 (red, preserved dry); ZMA Por. 16932, Jordan, Northern Gulf of Aqaba, Aqaba pier, 29.5167°N 35.0°E, depth 5 m , SCUBA, coll. I. K̂tter, field nr. 544, 2001 (red); ZMA Por. 16933, Jordan, Northern Gulf of Aqaba, in front of Marine Science Station , 29.5167°N 35.0°E, growing on water pipes at depth of 7 m , SCUBA, coll. I. K̂tter, field nr. 545, 2001 (red); ZMA Por. 16953, Jordan, Northern Gulf of Aqaba, in front of Marine Science Station , 29.5167°N 35.0°E, overgrowing dead Lobophyllia at depth of 10 m , SCUBA, coll. I. K̂tter, field nr. 9.5.1, 9 May 2001 (red, preserved dry) ; RMNH Por. 9145, Jordan, Northern Gulf of Aqaba, near Marine Science Station , 29.4583°N 34.9736°E, encrusting branching dead corals, 10–15 m depth , SCUBA, coll. L. Rix, field nr. 5, 8 December 2013 (red) .

Description ( Figs 29 a–f, 31a–c). ZMA Por. 14598 and RMNH Por. 9145 consist of larger alcohol preserved fragments, the other specimens are small wet and dried fragments, complemented by in situ and on deck photos. From these and from in situ photographs we can describe the species as forming encusting lobes on dead corals, in life ( Figs 29 a–b,e) with wide oscules of 3–10 mm or more in diameter on top of lobes, dark to bright red in color (although lighter, orange, colored inside), on deck they are also red, ( Figs 29 c–d,f), but in preservation they become dirty white ( Fig. 29d ). Surface smooth to bumpy-microconulose in life, more bumpy in preservation. The sponge is frequently hosting white scyphozoan polyps ( Fig. 29b ) and/or?polychaete tubes (see also Erhardt & Baensch 2000: 64). Size of encrusting specimens up to 5 cm in diameter, up to 3 cm in thickness. Consistency of the encrusting specimens soft, compressible. One of the collectors, R. Gómez ( Oman specimen ZMA Por. 14598) noted that it smelled after ‘canned tomatoes’. Production of slime not reported as excessive.

Skeleton ( Fig. 30a , 31d ). The skeleton consists of thick spicule tracts, 120–180 µm in diameter comprising>25 spicules in cross section, enclosed by spongin, interconnected at right angles by thinner, likewise sponginenforced spicule tracts, 30–50 µm in diameter comprising <10 spicules in cross section. The skeleton is confused and irregular. From these basal tracts issue peripherally directed thinner spicule tracts, 30–50 µm diameter without foreign material and with less visible spongin, and near the surface individual spicules fan out to carry the surface membrane ( Fig. 30a ), rather similar to what is seen in most Mycale (Carmia) species. Microscleres are generally rare, but sigmas may be more frequent in some specimens, both sigmas and anisochelae may be deficient in some specimens. No rosettes of anisochelae have been observed.

Spicules ( Figs 30 b–d, 31e–f). Mycalostyles, one size of anisochelae (if present), one size of sigmas (if present). If specimens have both microsclere types, they tend to have more sigmas than anisochelae, the latter being difficult to find or absent.

Mycalostyles ( Figs 30b,b 1 , 31e ,e 1 ), typically ‘hollow’, with visible axial canals, reduced in silica development, with elongately swollen tyles, length variable, 152– 238.6 –291 x 1– 2.49 – 3.5 µm.

Anisochelae ( Figs 30c , 31f ), usually quite rare, virtually absent in several specimens, occasionally a few are encountered, if present somewhat compressed and irregular, 12– 17.4 – 21 µm.

Sigmas ( Figs 30d , 31g ), also rare but definitely more often encountered and occasionally common, invariably thin, C- or S-shaped, usually asymmetric, 23– 35.1 – 40 µm.

Distribution and ecology. Our material is confined to the Arabian Peninsula, common in the Northern Gulf of Aqaba, also Oman. If indeed conspecific with M. (Ar.) tenuispiculata occurring also in Sri Lanka. Abundant on dead corals in open reefs, 5– 15 m.

Remarks. We are not certain our specimens belong to Dendy’s species. His type material (not seen) is similar in most aspects to our specimens, including the sandy interior and the uneven surface, but the paucity of microscleres (with anisochelae rare or absent) provides some doubts. Anisochelae were reported by Dendy as ‘scarce, but constant’, which concurs with our specimen from Oman, but the Aqaba material contained only a few anisochelae in four of the specimens, in one we did not find any.

Assignment of this species to the subgenus Arenochalina instead of Carmia is based on the irregular sponginenforced spicule tracts, but it is by no means certain. Our specimens share with Mycale (Arenochalina) mirabilis ( Von Lendenfeld, 1887) the rare presence of microscleres and the occurrence of sand grains and other foreign objects in the primary fibres, although this was rather uncommon. Differences are the color, which is cited as yellowish cream to beige (cf. Wiedenmayer 1989), and is bright red in our specimens. Mycalostyles in Australian M. (Ar.) mirabilis specimens appear distinctly thicker (2–8 µm) than in our Red Sea specimens (1–3.5 µm). Especially the color difference indicates that the Red Sea material is specifically distinct.

Esperella arenicola Ridley & Dendy, 1886: 339 ; Ridley & Dendy 1887: 72, pl. XV fig. 4, pl. XVI fig.8, from Bass Strait, South Australia, reassigned to Mycale arenicola by Hooper & Wiedenmayer (1994), on paper reads as rather similar to the present species, but mycalostyles and sigmas of that species are larger, and it has trichodragmas, not found in the present species. It may also be close to Mycale (Carmia) cockburniana Hentschel, 1911 . As the locality of arenicola falls outside our regional limits we do not add a summary description.

We suggest here that Burton’s (1952) record of Parisociella anomala ( Ridley & Dendy, 1886) (originally as Esperella ) is a member of the present species. His specimen had a skeleton resembling Mycale (Arenochalina) euplectellioides ( Row, 1911) (cf. above), and red live color. The shape was a macerated ‘fragment of a branch’ and low encrustations, with microscleres absent. The properties of Ridley & Dendy’s species, to which Burton had associated his Gulf of Aqaba specimens, are rather different and we do not think Burton’s material belongs to it. Ridley & Dendy describe a digitate irregularly ramose sponge, branches up to 12.5 cm, skeleton a rectangularly meshed reticulation of ‘stout spiculofibre’ containg a very large amount of spongin and few spicules. Megascleres were given as styles/tyostyles of about 250 x 5 µm, and rare microscleres in the form of very minute slender isochelae. Burton also mentioned the presence of toxas of 20–60 µm, apparently overlooked by Ridley & Dendy, and believed the isochelae were ‘degenerate’ anisochelae. Burton also gave several synonyms, which appear to be mostly Microcionidae .

Additional species of Mycale (Arenochalina) in the region

Figures

FIGURE 1. A. Numbers of available specimens for the present study from the collections of the Naturalis Biodiversity Center distributed over Indo-West Pacific Marine Ecoregions (MEOWS, cf. Spalding et al. 2007). B. Ditto for type specimens and additional specimens from other institutions consulted for this study.

FIGURE 29. Mycale (Arenochalina) aff. tenuispiculata (Dendy, 1905), a–d, RMNH Por. 9145, specimens from Jordan part of the Gulf of Aqaba, Red Sea (photos Laura Rix), a–b, in situ on dead coral, b, in situ not collected and with scyphozoan polyps, c, ditto on deck, d, preserved fragments (scale bar = 1 cm), e–f, specimens from Jordan part of the Gulf of Aqaba, Red Sea (photos Iris K̂tter), e, ZMA Por. 16926 in situ among Acropora corals, f, ZMA Por. 16953 on deck, on Lobophyllia coral.

FIGURE 30. Mycale (Arenochalina) aff. tenuispiculata (Dendy, 1905), a–d, RMNH Por. 9145 from the Gulf of Aqaba, a, light microscopic view of peripheral skeleton, b–d, SEM images of the spicules, b, mycalostyle, b1, details of mycalostyle, c, rare partially damaged anisochela, d, sigmas.

FIGURE 31. Mycale (Arenochalina) aff. tenuispiculata (Dendy, 1905), ZMA Por. 14598 from Oman, a–c, habitus, a, in situ (scale bar = 1 cm) (photo R. Gómez), b, detail in situ of specimen not collected (photo R. Gómez), c, specimen on deck (photo R. Moolenbeek), d, light microscopic image of choanosomal skeleton showing thick spicule tracts and sandy tissue, e–g, SEM images of spicules, e, mycalostyle, e1 details of mycalostyle, f, anisochela, g, sigma.