Floscularia wallacei, Segers & Shiel, 2008

Segers, Hendrik & Shiel, Russell J., 2008, Diversity of cryptic Metazoa in Australian freshwaters: a new genus and two new species of sessile rotifer (Rotifera, Monogononta, Gnesiotrocha, Flosculariidae), Zootaxa 1750 (1), pp. 19-31 : 27-29

Floscularia wallacei n. sp.

( Figs 4 – 6 )

Type material. Slide with holotype female (incl. part of tube, two resting eggs, RIR 181 ) , two paratypic trophi preparations ( RIR 183–184 ) , a slide with a colony consisting of one maternal specimen with first and second order offspring tubes attached ( RIR 185 ) , and a slide with a single specimen deposited in the Royal Belgian Institute of Natural Sciences ( RBINS - RIR 182 ; IG 30898 ) ; Slides with three paratypic females in tubes, with several eggs, a slide with a single specimen and a trophi preparation deposited in Museum Victoria, Melbourne ( NMV F 154553 ) .

Type locality. Ryan’s III billabong, near Bonegilla, Victoria, Australia: 36º 06’ 40.4” S / 146º 58’ 31.7” E. Specimens hatched from dry sediment .

Differential diagnosis. Table 2 gives a summary of diagnostic features of Floscularia species of the F. ringens group. Adults of the new F. wallacei have a long peduncle, which this species shares only with F. bifida Segers and F. pedunculata (Joliet) . The former has a pair of bifid mucrons on its posterior projection, whereas these are simple in F. wallacei n. sp. and F. pedunculata . The unci teeth of F.wallacei n. sp. and of F. bifida are strongly differentiated, while in F. pedunculata the differentiation is much less strong, and the trophi

are similar to F.armata Segers. Also , F. pedunculata is reported to have unique quadrilobed projections laterally under the corona; such projections are absent in the other species.

1 Feature to be assessed in mature specimens

2 Based on examination of a single specimen from an unspecified locality in India (Segers, unpublished)

Description. Body elongate, clearly separated into head, trunk and foot region, sessile, inhabiting an opaque tube built up of round pellets arranged in transverse rows. Tube narrowest basally, slightly widening towards distal opening. Corona slanted to dorsally, four-lobed, S-shaped in lateral view. Pair of ventral lobes largest, dorsal lobes separated by a relatively deep and narrow gap, ending in a wide, inverse V-shaped, unciliated region. A deep ciliated furrow between trochus and cingulum. Labium and ventral antennae elongate, modulus in usual position ventrally of the labium. Trunk and foot elongate, foot with long peduncle, length of foot and peduncle very variable depending on age. Parthenogenetic and resting eggs deposited near the basis of the tube, youngest eggs most superficial.

Animals sessile, either solitary or in small colonies in which larvae settle on the tube of their mother. Colonies containing up to three generations were observed. No males observed, resting eggs elongate, with low ridges in ellipses along longitudinal axis of the egg, similar to those of other Flosculariidae .

Trophi weakly asymmetrical, malleoramate, strongly sclerotised. Manubria crescent-shaped, consisting of superimposed dorsal, median and ventral chambers, separated by reinforced ridges and opening to caudally. Ventral manubrium tips connected to rami by strong ligaments. Rami inner margin proximally with large tooth-shaped median apophysis (two equal on left, a proximal large and distal smaller on right ramus). No free rami scleropili present. In caudal view, the rami exhibit a large proximal cavity divided in two by a septum. Right openings to subbasifenestrae larger than left. Alulae only indicated. Fulcrum short and narrow, with well-developed basal plate. Unci teeth fused complete shaft length; strong differentiation in a proximal group of large, and a distal group of weak teeth. Proximal group consisting of three subequal robust teeth on right uncus, left uncus with weakly developed proximal, and robust second and third tooth.

Measurements. Maximum length of live adult animal in tube (cultured) ca. 1,800 µm, of tube 1,600 µm, pellet diameter ca. 20 µm, corona width ca. 250 µm, peduncle length up to 230 µm. Trophi, 87–97 x 58–63 µm; largest uncus tooth ca. 28–34 µm, ramus half 39 x 20 µm; manubrium 35–44 µm; fulcrum 12–17 µm. Resting egg 150 x 75 µm.

Etymology. This new species is dedicated to Dr R.L. Wallace (Patricia and Philip McCullough Professor of Biology, Ripon College, Ripon, WI, USA), in recognition of his outstanding contribution to the knowledge of rotifers in general, and of sessile rotifers in particular.

Figures

FIGURE 4. Floscularia wallacei n. sp. 4a: habitus, young (left) and adult (right) specimen, 4b: head and corona, lateral view, 4c: head and corona, dorsal view.

FIGURE 5. Floscularia wallacei n. sp., neck spines, SEM pictures. 5a: dorsal, 5b: lateral. Scale bar10 µm.

FIGURE 6.Floscularia wallacei n. sp., trophi SEM pictures. 6a: frontal view, 6b: caudal view, 6c: detail. Scale bars: 10 µm.