Plumatella tsimiheta, Wood & Unger & Rasoamihaingo, 2023

Wood, Timothy S., Unger, Lilian Eva & Rasoamihaingo, Laurence, 2023, Bryozoan statoblasts from lake sediments in Madagascar, including two new species, European Journal of Taxonomy 900 (1), pp. 138-147 : 140-142

Plumatella tsimiheta sp. nov.

urn:lsid:zoobank.org:act:BD3A02EE-5785-45B7-A3DB-E939BE6A59FB

Fig. 3

Diagnosis

Floatoblasts unusually long and narrow, the outer dimensions similar to Plumatella dhritiae Wood, 2022 ; fenestra tubercles well formed and densely crowded, spilling onto the annulus in a manner resembling P. patagonica Wiebach, 1974 .

Etymology

The species name is a tribute to the local ethnic group, the Tsimihety, who inhabit much of the northern Madagascar.

Material examined

Holotype

MADAGASCAR • Statoblast valves; Mahajanga Province, Sofia Region, Bealanana District, Marotolana Village, Lake Sofia ; 14°35′04″ S, 49º00′30″ E; Sep. 2019; L. Unger leg.; NHMUK 2023.1.17.1 , slide collection.

Description

Floatoblast 51–535 µm long ( Fig. 3a ) with an average of 530 µm and 245–255 µm wide with an average of 253 µm (n = 3), length: width averaging 2.16; capsule measuring 360 µm by 215 µm; dorsal valve nearly flat, with fenestra encroaching on underlying capsule only at the poles ( Fig. 3a , arrows); ventral valve convex, with fenestra matching capsule outline; fenestra tubercles small, densely crowded and highly convex, merging indistinctly with annular cells surrounding the fenestrae; other annular cells mostly defined by low mounds; suture appearing as crenulated margin around entire floatoblast ( Fig. 3b ).

Remarks

While the floatoblast outer dimensions resemble those of Plumatella dhritiae Wood, 2022 , in that species the dorsal fenestra encroaches uniformly on all sides of the capsule, fenestra tubercles are well spaced, and the outer margin is smooth. Floatoblast tubercles in P. tsimiheta sp. nov. resemble those of P. patagonica Wiebach, 1974 in their size, density, and distribution ( Fig. 3c ). However, in that species the floatoblast is over 750 µm in length and more broadly oval.

Figures

Fig. 3. Floatoblasts related to Plumatella tsimiheta sp. nov. a. Unpaired valves, dorsal on left with arrows showing annulus encroachment over the capsule, image of ventral valve (right) electronically composed to show two planes in focus. b. SEM micrograph showing floatoblast surface details on dorsal (left) and ventral (right) valves. c. SEM view of a portion of floatoblast in P. patagonica Wiebach, 1974 showing similar tuberculation. Scale bars: a–b = 100 µm; c = 50 µm.