Siphonodictyon Bergquist, 1965

Ubare, Vibha V. & Mohan, P. M., 2018, New Records and Range Extensions of Some Marine Sponges (Porifera: Demospongiae and Homoscleromorpha) from the Andaman Islands, India; Part of the Indo-Burma Biodiversity Hotspot., Zoological Studies 57 (3), pp. 1-15 : 7

Genus Siphonodictyon Bergquist, 1965 Siphonodictyon mucosum ( Bergquist, 1965)

( Figs. 8 and 9 )

Synonyms: Aka mucosa ( Bergquist, 1965) (Junior synonymy with insect genus Aka White, 1879 . Reverting to the original name.)

Siphonodictyon mucosa Bergquist, 1965 (agreement in gender)

Material examined: 1 ex., DOSMB 00178 India: Andaman and Nicobar Islands: North Andaman: Diglipur, Coll. Vibha Ubare, 14.xii.2013.

Description: Here this species is described on the basis of fistulae alone ( Fig. 8A ). The sponge is mainly boring, only the fistular portion is externally visible. The remaining sponge body is present inside the rocky substratum. The fistular portion is very short, some are bifurcated. The length of the fistula ranges from 16.1-32.3 mm and diameter ranges are 5.6-9.9 mm. The colour of the specimen is blackish brown in live condition and grayish internally, no change occurs after preservation. The consistency is firm, brittle, and compressible. It oozes out. The surface is hispid, oscules may be present but not visible.

Spicules: Megascleres- Only oxeas ( Fig. 8B ) are present, it is straight, smooth and measures 185.0-216.0/10.0-10.2 µm. Microscleres is absent.

Skeleton: The ectosomal skeleton shows oxeas arranged in the reticulate pattern. Oxea are attached to each other with the spongin present at the tip portion. In the choanosomal region the oxeas are running parallel to the wall of the sponge. It is arranged in a multispicular reticulation pattern ( Figs. 8 C-F).

Habitat: Boring sponge, only fistulae are visible from the outside and present on the sandy substratum.

Distribution: India: Not reported anywhere in India. The present study reported it in Diglipur; Elsewhere - West Caroline Islands ( Bergquist 1965) and Western Sumatra ( Rützler 1971) ( Fig. 9 ).

Remarks: This species has been reported for the first time from India. There are two species from this genus that were earlier reported from the Indian region viz. Siphonodictyon diagonoxeum (Thomas, 1968) and Siphonodictyon minutum (Thomas, 1972) . The new record, Siphonodictyon mucosum oozes more mucus than these two species and its oxea size is also larger (185.0- 216.0/10.0-10.2 μm) than S. diagonoxeum (109.0- 130.0/7.0-8.0 μm) and S. minutum (85.0-141.0/1.0- 7.0 μm).

Figures

Fig. 8. Siphonodictyon mucosum Bergquist, 1965. (A) Specimen after preservation. (B) Oxea. (C) Longitudinal section. (D) Longitudinal section. (E) Transverse section. (F) Transverse section.

Fig. 9. Geographical extension of Siphonodictyon mucosum Bergquist, 1965. © 2018 Academia Sinica, Taiwan