Didemnum microthoracicum Kott, 2001

Kott, Patricia, 2005, New and little-known species of Didemnidae (Ascidiacea, Tunicata) from Australia (Part 3), Journal of Natural History 39 (26), pp. 2409-2479 : 2448

publication ID	https://doi.org/ 10.1080/00222930500087077
persistent identifier	https://treatment.plazi.org/id/7352D565-FB1A-FF9A-FE41-FDAA65B9FA51
treatment provided by	Felipe
scientific name	Didemnum microthoracicum Kott, 2001
status

Treatment

Didemnum microthoracicum Kott, 2001 View in CoL

( Figures 8C View Figure 8 , 20F View Figure 20 )

Didemnum microthoracicum Kott, 2001, p 207 View in CoL .

Distribution

Previously recorded (see Kott 2001): South Australia (Great Australian Bight,? Reevesby I.). New record: South Australia (Kangaroo I., SAM E3256 View Materials ) .

Description

The newly recorded colony is a thin encrusting sheet with a quilted surface caused by the surface depression over common cloacal canals that surround zooid-free pillars of solid test. Zooids line the canals. In life, blue pigment is in the surface test over the common cloacal canals. Large sessile common cloacal apertures with spicule-free transparent rims are at the junctions of some of the canals. Spicules are crowded throughout the colony beneath a thin superficial layer of bladder cells. They are relatively large (to 0.09 mm diameter), stellate with seven to nine robust conical pointed rays in optical transverse section. The thoraces are small with no more than six stigmata per row. Gonads were not detected.

Remarks

The relatively large spicules of this species and its circular common cloacal canals around surface elevations of zooid-free test distinguish it from other Didemnum spp. with small zooids and crowded stellate spicules with relatively few rays. Didemnum corium sp. nov. differs in its spicule distribution, the spicules being confined to a layer in the surface, a layer lining the common cloacal cavities and another on the base of the colony; and in the apparent absence of a quilted colony surface.