Reteporellina, Harmer, 1933

Martino, Emanuela Di & Taylor, Paul D., 2018, Early Pleistocene and Holocene bryozoans from Indonesia, Zootaxa 4419 (1), pp. 1-70 : 56

Reteporellina sp.

( Figs 164–170 ; Table 37)

Figured material. RGM.1350591, RGM.1350592, Holocene, UPGG 041, off South Sulawesi.

Description. Colony erect, rigid, dichotomously branching at angles of 40–50˚; branches twisted and curved, 0.55–0.85 mm wide, narrower after bifurcation. Autozooids arranged in 3–5 alternating longitudinal rows, distinct, bordered by a thin, raised rim of smooth calcification, flask-shaped to irregularly polygonal, longer than wide (mean L/W = 1.47). Frontal shield flat to gently convex, nodular, imperforate except for a pair of circular, marginal areolar pores placed proximally, 10–18 µm in diameter. Primary orifice deep, hidden by the peristome; secondary orifice elliptical, about 100 µm long by 70 µm wide; proximal rim undulose with a median, U-shaped peristomial groove. Oral spine bases absent. An adventitious avicularium, variable in size (up to 90 µm long by 60 µm wide), may occur on the peristome rim to one side of the sinus, directed proximolaterally; rostrum raised, triangular; crossbar complete. Frontal avicularia absent. Ooecia small, globular but all broken or incomplete. Abfrontal surface nodular, divided into irregular polygonal sectors by vibices; within each sector sparse, small circular pores; a single, rounded triangular avicularium, 100 µm long by 50 µm wide, with complete crossbar, was observed.

Remarks. Thirteen fragments of Reteporellina sp. were found in our samples. Reteporellina is distinguished from other phidoloporids in having a deep peristome with undulose proximal rim bearing a central peristomial groove. Unfortunately, ooecia in our specimens are either broken or incomplete, preventing species identification. The tropical Indo-West Pacific R. babelensis ( Chapman, 1941) has a large peristomial avicularium, which differs from the fossil material in having distal cusps.

N, Number of colonies and number of zooids measured; SD, standard deviation.

Figures

FIGURES 164–170. Reteporellina sp., Holocene, UPGG041, off South Sulawesi. 164–168. RGM.1350591. 164. General view of a colony fragment. 165. Group of autozooids. 166. Group of ovicellate zooids. 167. General view of the abfrontal surface. 168. Close-up of the abfrontal surface with an avicularium (right). 169, 170. RGM.1350592. 169. Close-up of an autozooid with large peristomial avicularium but orifice sealed by secondary calcification. 170. Close-up of two peristomial orifices with median peristomial groove and ooecium. Scale bars: Figs 164, 167 = 500 µm; Figs 165, 166 = 200 µm; Figs 168–170 = 100 µm.