Bioacoustics of Zoothamnium plumula

Remarks. The Chinese population of Z . plumula that we examined is characterized mainly by the following characters: alternately branched stalk, feather-shaped outline of colony, presence of larger zooids at some points on secondary stalks, and marine habitat. Characteristics of the colonies that we observed matched well with both the original description by Kahl (1933 , 1935 ; Figs. 1 B, C) and the redescription by Song et al . (2002 ; Figs. 1 A, G). Consequently, the identification of our samples as Z. plumula is beyond reasonable doubt. In the experience of the senior author, Z . plumula is usually abundant in eutrophic waters and is accompanied by Z. alrasheidi Ji et al ., 2009 , which forms a large, leaf-shaped colony with a similar branching pattern. However, the latter species can be distinguished from Z . plumula easily by differences in infraciliature and number of silver lines, its larger zooids (80–120 × 50–60 µm vs. 50–75 × 35–45 µm), and its thick peristomial lip, which has a prominent circumferential infolding (Ji et al . 2009). At first glance, two other marine congeners, Z. alternans Claparède and Lachmann, 1859 and Z. niveum Ehrenberg, 1838 , are very similar to Z . plumula in shape of the colony, branching pattern, and presence of macrozooids. However, zooids of both Z. alternans and Z. niveum have different sizes than those of Z. plumula (40–56 × 26–32 µm and 54–66 × 16–22 µm vs. 50–75 × 35–45 µm), and the macrozooids of both species are located on the primary stalk rather than in on the middle or distal parts of secondary branches, as in Z . plumula . In addition, Z. niveum forms a considerably larger colony (> 1 cm vs. 3 mm in Z. plumula ) ( Bauer-Nebelsick et al . 1996 ; Ji et al . 2006 b ). Characters Min Max Mean SD n Number of silverlines from Z. plumula 50 60 54.5 3.36 11 peristomial lip to trochal Z. nii 47 58 52.1 3.38 15 band Z. wangi 70 85 76.4 4.63 8 P. bidulphiae 25 31 28 2.26 10 P. m a r i n a 25 30 27.5 - 4 Number of silverlines from Z. plumula 22 27 25.3 1.57 10 scopula to trochal band Z. nii 22 30 27.4 3.04 11 Z. wangi 38 50 44.2 4.46 12 P. bidulphiae 9 13 11.6 1.30 8 P. m a r i n a 10 15 12 1.79 6