Varunella coronifera Wiebach, 1974

Nimbalkar, Nirmiti D., Wood, Timothy S. & Chondekar, Ramesh P., 2022, Description of Varunella coronifera in India (Bryozoa: Phylactolaemata), Records of the Zoological Survey of India 122 (3), pp. 287-290 : 288-289

Varunella coronifera Wiebach, 1974

Description: Wiebach (1974) described the colony as having a body wall that is soft, unsclerotized, thick and firm; the colony growing close to the substratum, with branches fused near the centre but dendritic around the periphery; zooids arising from conical protrusions in the basal tubules. Wiebach’s Figures 6 and 7 show floatoblasts that are broadly oval with sides nearly parallel along the midpoint; both dorsal and ventral fenestrae are small and nearly circular, their lengths no more than a third of the overall statoblast length; the ventral fenestra finely tuberculated and considerably smaller than the underlying capsule. Floatoblast dimensions were given as 0.382 -0.468 mm long and 0.272 -0.374 mm wide. Sessoblasts were described as having two forms: in one the frontal valve is fully covered by tubercles, in the other, the tuberculation is interrupted by a circular formation of irregular lumps halfway between the sessoblast centre and the annulus; the annulus in both sessoblast forms was reticulated; dimensions described as 0.382 -0.448 mm long and 0.272 -0.374 mm wide.

Although the recent specimen from Mombata Reservoir consists only of a single sessoblast, the morphology is highly unusual and matches one of the sessoblast forms described by Wiebach (1974). The frontal valve bears distinct tubercles and a central eruption of lumps arranged roughly in a circle ( Figure 1a, b ). The annulus is clearly reticulated. The sessoblast measures 274 µm long and 222 µm wide.

In Rao’s material, the thick body wall and fused basal branches of the colony are clearly evident. There are no internal septa and no evidence of external raphe. Floatoblast morphology matches that described by Wiebach (1974) (Figure 2a). Many sessoblasts lack the central lumps, but the tubercles are prominent, conforming to one of the forms described by Wiebach (1974) (Figure 2b). Statoblast dimensions from the Kshipra material are presented in Table 1.

Figures

Figure 1. Statoblasts from recent collections of Varunella coronifera. (a) Sessoblast from Mombata Reservoir showing unique lumps on the frontal valve, scale bar = 100 µm; (b) Magnified view of the same sessoblast, scale bar = 50 µm; (c) Floatoblast valves from Kshipra River specimen, with dorsal valve on the left, scale bar = 100 µm; Sessoblast from the Kshipra River specimen, showing pattern of tuberculation and lacking the lumpy feature; scale bar = 100 µm.