Dynamena heterodonta ( Jarvis, 1922 )

Galea, Horia R., 2016, Notes on some sertulariid hydroids (Cnidaria: Hydrozoa) from the tropical western Pacific, with descriptions of nine new species, European Journal of Taxonomy 218, pp. 1-52 : 6

Dynamena heterodonta ( Jarvis, 1922)

Fig. 1 L–O

Pasythea heterodonta Jarvis, 1922: 344 , pl. 24, figs 11–12.

Dynamena heterodonta – Billard 1925b: 198, fig. 44. ― Redier 1966: 86. ― Vervoort & Vasseur 1977: 36, figs 16–17.

Sertularia gracilis – Billard 1905: 334 (not Sertularia gracilis Hassall, 1848: 2223 ).

non Dynamena quadridentata f. heterodonta – Vannucci 1951a: 83; 1951b: 108, 112, 114 [= D. quadridentata (Ellis & Solander, 1786) ].

Material examined

MUSORSTOM 9: Stn. DW1204, small colony composed of four infertile stems, 6–12 cm high, detached from substrate (MNHN-IK-2012-16517); Stn. DW1265, sterile colony with stems up to 2.6 cm high, epizoic on Synthecium sp. (MNHN-IK-2012-16518).

Remarks

The sterile, unbranched stems, divided here and there by oblique nodes, each of which comprises a varied number of isolated hydrothecal pairs, occasionally forming apically stacked groups of two, the lack of evidence of an abcauline caecum in retracted hydranths, the two-cusped hydrothecae with a pleated adcauline flap and a semicircular abcauline flap, and the inconstant presence of internal, submarginal cusps in the hydrothecae suggest that they belong, with little doubt, to Jarvis’ (1922) species.

Vervoort & Vasseur (1977) provided a reexamination of the type material, as well as a discussion regarding its differences with D. quadridentata (Ellis & Solander, 1786) .

Geographical distribution

St. Brandon (Cargados Carajos) ( Jarvis 1922), Indonesia ( Billard 1925b), New Caledonia ( Redier 1966), French Polynesia [ Billard (1905), as Sertularia gracilis Hassall, 1848 ; Vervoort & Vasseur (1977); present study].

Figures

Fig. 1. ― A–B. Caminothujaria molukkana von Campenhausen, 1896 (BORDAU 2, Stn. CP1582). A. Fragment of internode with verticil of hydrothecae. B. Gonotheca. ― C–J. Diphasia cristata Billard, 1920 (BORDAU 1, Stn. CP1448). C. Pair of hydrothecae, frontal view. D. Same, dorsal view. E. Cross section through basal part of hydrothecal pair, showing perisarcal crests. F. Female gonotheca. G. Same, apical view. H. Same, cross section. I. Male gonotheca. J. Same, apical view. ― K. Diphasia orientalis Billard, 1920 (MUSORSTOM 3, Stn. DR117), internode with pair of hydrothecae. ― L–O. Dynamena heterodonta (Jarvis, 1922) (MUSORSTOM 9). L. Pair of hydrothecae in material from Stn. DW1204. M. Same sample, hydrothecal aperture, showing internal, submarginal cusps. N–O. Isolated (N) or stacked (O) pairs of hydrothecae in material from Stn. CP1265. ― P. Geminella ceramensis Billard, 1925a (MUSORSTOM 8, Stn. CP1084), internode with pair of hydrothecae. Scale bars: A–D, K–L, N–P = 500 µm; E = 400 µm; F–J = 1 mm; M = 100 µm.