Cossura, Webster & Benedict, 1887

Zhadan, Anna, 2015, Cossuridae (Annelida: Polychaeta: Sedentaria) from Australian and Adjacent Waters: the First Faunistic Survey, Records of the Australian Museum 67 (1), pp. 1-24 : 16-18

Cossura sp. cf. pygodactylata Jones, 1956

Fig. 14

Cossura pygodactylata Jones, 1956: 127 , fig. 1a–f.

Type locality. San Francisco Bay , California .

Material examined. New South Wales. 2 specimens (1 complete), Botany Bay , 200–500 m west of runway extension (33°57'49"S 151°10'26"E), 06 Apr. 1992, depth 7 m, Smith- McIntyre grab, col. Australian Museum party, W.21514; 2 specimens (1 complete), Clyde River Estuary (35°42'25"S 150°08'20" E), 01 Dec. 2010, depth 2 m, col. K. Dafforn , W.43215.

Description. Body length of complete specimen from W.21514 about 4.1 mm, width about 330 μm, 40 chaetigers. 13–17 thoracic chaetigers, without sharp border between regions ( Fig. 14A ). Segments not swollen, without glandular pads dorsally ( Fig. 14F ). Chaetal bundles arising from anterior borders of segments in thorax; shifted to the middle part of the segments on the abdomen; chaetae become less numerous and thinner, segments become longer in the abdomen ( Fig. 14A ).

Prostomium conical; prostomial furrow weakly developed; posterior ring when present as long as peristomium ( Fig. 14B,C,E,F ). Branchial filament arising from middle-posterior part of chaetiger 2 ( Fig. 14F,G ).

Chaetiger 1 with uniramous parapodia, all next segments bearing biramous parapodia. All chaetae hirsute capillaries, in anterior chaetigers arranged in two indistinct rows. Thicker and shorter chaetae in anterior part of thorax; thinner and longer ones in posterior thorax and abdomen. Notochaetae as thick as neurochaetae ( Fig. 14B,G ).

Pygidium with three long cirri and 8–12 shorter intercirral processes ( Fig. 14D,H ).

Complete specimen (W.21514) bears oocytes in body cavity.

Remarks. Cossura pygodactylata Jones, 1956 is the single cossurid species known to bear intercirral anal processes (another such species, C. lepida Tamai, 1986 from Japan, was synonymized with C. pygodactylata by Hilbig [1996]). This species has a wide geographical distribution and is rather variable by size and number of thoracic segments. Probably different geographical populations belong to different but morphologically similar species. This question requires further investigations using molecular methods. Australian worms correspond with descriptions of C. pygodactylata from California, Japan, Atlantic ( France) and White Sea ( Russia). Cossura sp. cf. pygodactylata is also very similar with C. sp. cf. longocirrata when posterior end is missing by branchial filament arising from chaetiger 2, conical shape of prostomium and number of thoracic chaetigers; differences are C. sp. cf. longocirrata has neurochaetae notably thicker than neurochaetae in anterior thorax whereas in C. sp. cf. pygodactylata this difference is less pronounced.

Figures

Figure 14. Cossura cf. pygodactylata Jones, 1956. Light microscopy, A–D (W.21514) compound microscope, E–H (W.43215) stereomicroscope. (A) general lateral view; (B) anterior end, lateral view; (C) anterior end, dorsal view; (D) pygidium, ventral view; (E) general view; (F) anterior end, dorsal view; (G) anterior end, lateral view; (H) posterior end with pygidium, ventrolateral view. Scale bars:A = 500 μm; B–D, F, H = 100 μm; E, G = 300 μm.