Pleurocodonellina javanensis, Martino & Taylor, 2018

Martino, Emanuela Di & Taylor, Paul D., 2018, Early Pleistocene and Holocene bryozoans from Indonesia, Zootaxa 4419 (1), pp. 1-70 : 29-30

Pleurocodonellina javanensis n. sp.

( Figs 81–85 ; Table 18)

Figured material. Holotype, RGM.1350564, early Pleistocene, Java.

Diagnosis. Colony encrusting. Autozooids polygonal. Frontal shield dimpled with a single row of areolar pores. Orifice with a semicircular anter, squared sinus and robust condyles devoid of denticulations. Peristome most developed proximally. Oral spines present. A single proximolateral, adventitious avicularium proximally directed, elliptical, slightly spatulate or rounded triangular. Ooecium globular, covered distally by secondary calcification, ectooecium perforated frontally by numerous small pores.

Etymology. Named after the Indonesian island of Java, at present its unique geographical record.

Description. Colony encrusting, multiserial, unilaminar. Ancestrula overgrown, presumably tatiform, surrounded by five zooids slightly smaller in size than succeeding autozooids. Autozooids distinct with deep interzooidal furrows containing salient lateral walls, arranged quincuncially, irregularly polygonal, longer than wide (mean L/W = 1.46). Frontal shield slightly convex, smooth, dimpled, bordered by a single row of large and numerous areolar pores, 25–35 µm in diameter. Orifice almost equidimensional if the sinus is included in the measure of its length, with a small squared sinus separated from the semicircular anter by a robust pair of condyles devoid of denticulations. Peristomial rim encircling the orifice, most developed proximally. An uncertain number of oral spine bases present, covered early in ontogeny by the development of the peristome. Adventitious avicularia dimorphic, proximolateral, suboral, unpaired, proximally directed, complete crossbar; most commonly elliptical parallel-sided or slightly spatulate, rarely triangular with rounded tip. Ooecium immersed, globular, broader than long, covered distally by secondary calcification, ectooecium perforated frontally by numerous (ca 30–40), small, circular to oval pores, 10–15 µm in maximum diameter.

Remarks. A single colony of Pleurocodonellina javanensis n. sp. was found in our samples, encrusting a bivalve shell fragment. The Pleistocene species is similar in appearance to P. signata ( Waters, 1889) , recorded as having an almost circumtropical distribution but in need of further revision after the partial review of Tilbrook (2006). However, P. signata differs in having minutely denticulate condyles, a proportionally smaller drop-shaped sinus, elongate triangular avicularia, and much larger zooids. A Burdigalian species tentatively assigned to Pleurocodonellina was found in Kalimantan (Di Martino & Taylor 2015, p. 23), but differs in having much larger zooids and in the shape of the avicularia.

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

Figures

FIGURES 81–85. Pleurocodonellina javanensis n. sp., holotype, RGM.1350564, early Pleistocene, Java. 81. General view of part of the colony including early astogeny. 82. Group of zooids; note the two, oral spine bases visible on the distal orificial edge of the zooid at the bottom. 83. Close-up of two zooids with lateral avicularia of different shapes. 84. Close-up of an orifice. 85. Ovicellate zooids. Scale bars: Fig. 81 = 200 µm; Figs 82, 83, 85 = 100 µm; Fig. 84 = 50 µm.