Parasmittina agathae Hayward & Parker, 1994

Martino, Emanuela Di & Taylor, Paul D., 2018, Early Pleistocene and Holocene bryozoans from Indonesia, Zootaxa 4419 (1), pp. 1-70 : 26-27

Parasmittina agathae Hayward & Parker, 1994

( Figs 71–76 ; Table 16)

Smittia spathulata: Kirkpatrick, 1890: 619 , pl. 17, fig. 1.

Parasmittina agathae Hayward & Parker, 1994: 55 , fig. 1A–F.

Figured material. RGM.1350562, Holocene, UPGG 041, off South Sulawesi.

Description. Colony encrusting, multiserial, multilaminar. Autozooids irregularly arranged, rectangular to irregularly polygonal, distinct by narrow sutures, longer than wide (mean L/W = 1.59). Frontal shield flat to slightly convex, coarsely nodular, outlined by a single row of marginal areolar pores, circular to oval, 20–40 µm long. Primary orifice broader than long, about 65 µm long by 80 µm wide, apparently with a coarse denticulation on the distal edge; lyrula robust, broad, occupying about half width of the proximal orificial edge, trapezoidal; condyles pointed, downwardly directed. Two distal oral spine bases visible in some zooids. Peristome thick, most developed proximolaterally, producing a pair of prominent flaps. Adventitious avicularium placed laterally to the orifice, proximally or proximolaterally directed, polymorphic and variably sized, most often small and oval (about 55 µm long by 45 µm wide) or spatulate (about 100 µm long by 40 µm wide), rarely large and spatulate (285 µm long by 80 µm wide); crossbar complete. A triangular avicularium, about 60 µm long by 40 µm wide, with a raised rostrum, steeply inclined on the frontal plane and distolaterally directed inwardly, was observed placed on the proximal corner of two zooids. Ovicell represented by a single broken example lacking the roof, outline rounded, about 170 µm long by 220 µm wide.

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

Remarks. A single colony fragment of Parasmittina agathae was found in our samples. This species at the present-day is known from Queensland and the Torres Strait at 12–36 m depth. It is characterized by the coarsely denticulate distal border, the prominent, lateral peristomial flaps, the relatively broad lyrula, the two distal oral spines, and the unique combination of adventitious avicularia variable in size and shape. Hayward & Parker (1994) also described for this species an erect, three-dimensional structure of hollow tubes developing from an encrusting base. Parasmittina dentigera Harmer, 1957 is similar to P. agathae in having an orifice with a denticulate distal border, but differs in having a peristome that is especially prominent proximally, and a distinct anvil-shaped lyrula.

Figures

FIGURES 71–76. Parasmittina agathae Hayward & Parker, 1994, RGM.1350562, Holocene, UPGG041, off South Sulawesi. 71. General view of the colony fragment. 72. Group of zooids with small oval and large spatulate avicularia, and broken ooecium. 73. Close-up of a large spatulate avicularium. 74. Close-up of an orifice with two distal oral spine bases, denticulate distal edge and laterally prominent peristome. 75. Close-up of a zooid with a small spatulate avicularium. 76. Close-up of a zooid with a steeply inclined, small triangular avicularium on the distolateral corner. Scale bars: Fig. 71 = 500 µm; Fig. 72 = 200 µm; Figs 73–75 = 50 µm; Fig. 76 = 100 µm.