Cossura queenslandensis, Zhadan, 2015

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 : 20

publication ID 10.3853/j.2201-4349.67.2015.1639

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scientific name

Cossura queenslandensis


Cossura queenslandensis n.sp.

Figs 15 View Figure 15 , 16 View Figure 16

Type locality. Queensland, Calliope River, Gladstone .

Type material. Holotype fragment 10.5 mm long, 0.36 mm wide, 35 chaetigers, slides of 36th and 37th chaetigers, Queensland, Calliope River, Gladstone (23°51'S 151°10'E), depth 8.3 m, sandy mud, Oct. 1977, coll. P. Saenger, Trans. 5, Stn. 2, W.16477 GoogleMaps . Paratypes 19 specimens, Queensland, Calliope River, Gladstone (23°51'S 151°10'E), depth 1.3 m, sandy mud, Oct. 1977, coll. P. Saenger, Trans.10, Stn.2, W.16432; paratype SEM pin mount, Queensland, Calliope River , Gladstone (23°51'S 151°10'E), depth 1.3 m, sandy mud, Oct. 1977, coll. P. Saenger, Trans. 10, Stn. 2, W.42863 GoogleMaps .

Additional material examined. Queensland. 100+ specimens including complete, Calliope River, Gladstone (23°51'S 151°10'E), 1974, coll. P. Saenger, W.199308; 4 specimens GoogleMaps , SEM stub mounts, Calliope River, Gladstone (23°51'S 151°10'E), 1974, coll. P. Saenger, W.43260; 2 specimens GoogleMaps , mouth of Althaus Creek, Halifax Bay, north of Townsville (19°10'S 146°36'E), depth 2 m, 1977, coll GoogleMaps . Queensland Nickel, W. 202193; 5 specimens , Halifax Bay , 85­2­B4, W.43338; 7 specimens , Auckland Creek, Gladstone (23°51'S 151°14'E), Aug. 1976, coll. P. Saenger, Trans. 3, Stn. 3, W.13222 GoogleMaps .

Description. Complete specimens are 29–90 mm long, 250–300 μm wide, with 43–66 chaetigers. 17–20 thoracic chaetigers, no sharp border between body regions. Body thickest in anterior abdomen, tapering to both ends ( Fig. 15A,E,F View Figure 15 ). Segments not swollen, without glandular pads or biannulations dorsally ( Figs 15G View Figure 15 , 16J View Figure 16 ). Chaetal bundles arising from anterior border of segments in thorax; shifted to the middle part of segments in the abdomen; in abdomen chaetae less numerous and thinner, segments longer ( Fig. 15A View Figure 15 ). No bead-like segments in posterior abdomen ( Fig. 15E,F View Figure 15 ).

Prostomium blunt conical, with round tip and broadened base ( Figs 15B,G View Figure 15 , 16B,L View Figure 16 ). Prostomial furrow developed in some specimens, posterior prostomial ring shorter or as long as peristomium. Lateral margins of prostomium straight or concave ( Fig. 16L View Figure 16 ). Branchial filament attached to segmental border between chaetigers 2 and 3; in well relaxed specimens it looks closer to chaetiger 2, in others closer to chaetiger 3 ( Fig. 15G, H, I View Figure 15 , 16C, I, J View Figure 16 ). One specimen with 6 everted buccal tentacles, in others tentacles inverted.

Chaetiger 1 with uniramous parapodia, all the next segments with biramous parapodia with closely arranged rami. All chaetate hirsute capillaries, arranged in two rows, especially clear in anterior chaetigers ( Fig. 15H, I View Figure 15 , 16C, F, G, I, J View Figure 16 ). Thicker and shorter chaetae located in anterior row, thinner ones in posterior. First chaetiger bearing 4–7 chaetae; in next thoracic segments 4–5 + 3–4 chaetae in notopodia and 4–5 + 3–4 in neuropodia in anterior and posterior rows, respectively. Difference in thickness of chaetae little, notochaetae and neurochaetae of same width ( Fig. 15H, I, J, K View Figure 15 ). In abdominal segments 3–4 long thin capillaries in notopodia and 4–5 in neuropodia ( Fig. 16M View Figure 16 ).

Pygidium with three middle-long anal cirri, without intercirral processes ( Fig. 15C, J–L View Figure 15 , 16E, N View Figure 16 ). Anal cirri easily lost, most specimens bearing one or two cirri, in some cases they are short, most probably regenerating.

Etymology. Named after type locality.

Remarks. Cossura queenslandensis n.sp is very similar to C. cf. longocirrata . Main differences are: 1, C. queenslandensis has a bigger and longer body; 2, the tip of the prostomium is more round in C. queenslandensis ; 3, C. queenslandensis has more thoracic chaetigers, 17–20 instead of 13–15 in C. cf. longocirrata (but this character is variable in both species); 4, thoracic neurochaetae and notochaetae have almost the same width (in C. cf. longocirrata neurochaetae are thicker); 5, C. queenslandensis was found in Queensland, C. cf. longocirrata in NSW.

Cossura consimilis Read, 2000 is similar with C. queenslandensis n.sp. by the attachment of branchial filament, the round tip of conical prostomium, the shape of anterior chaetae, but this species is bigger and longer (average width 460 μm and up to 660 μm, up to 17 mm long) and has more thoracic chaetigers (21–32 instead of 17–20 in C. queenslandensis ).