Antomma elegans (Fraser, 1937) Galea & Di Camillo & Maggioni, 2021

Galea, Horia R., Di Camillo, Cristina G. & Maggioni, Davide, 2021, An integrative study of Callicarpa gracilis Fewkes, 1881 and Aglaophenia trifida L. Agassiz, 1862, with notes on some hydroids (Cnidaria: Hydrozoa) from French Guiana, Zootaxa 4926 (3), pp. 301-341 : 333

Antomma elegans (Fraser, 1937) , comb. nov.

Fig. A4

Hippurella elegans Fraser, 1937: 5 , pl. 2 fig. 9.—Fraser, 1944: 332, pl. 71 fig. 321.

Description. Colonies up to 35 cm high, with fascicled stems, whose lower half is devoid of branches and hydrocladia; upper half bearing long, slender branches, given off either singly or, commonly, in nearly opposite pairs; branches arising in all direction around the stem; stem and branches with indistinct divisions; equivalents of internodes with a proximal nematotheca, a latero-distal cladial apophysis with 2 nematothecae, as well as an additional nematotheca below; cladia given off at an angle of ca. 60°, arranged regularly alternately along the branches; homomerously (?) divided into long internodes, each with a proximal hydrotheca and its complement of 3 nematothecae (one mesial and a couple of laterals), as well as a distal nematotheca, above the hydrotheca; hydrothecae deep, tubular, abaxial walls slightly sinuated, margins entire; gonosome on distal portions of some branches; composed of staked whorls of up to 8 rows of 6 slender, distally tapering, unbranched, nematothecate ramuli, curving out- and upward from the common rachis; gonothecae elliptical, smooth-walled, borne singly or in pairs on the axils of ramuli.

Remarks. Antomma elegans was distinguished from A. longicarpa through the “hydrocladial internodes without septa” (Fraser 1944) and, consequently, its relationships to the latter remain obscure, pending the reexamination of the type, Fraser’s illustrations being qualitatively poor to sufficiently highlight its specific differences.

Distribution. Off Puerto Rico (18°31’30’’ N, 66°18’20’’ W, depth not recorded; 18°24’45’’ N, 67°14’15’’ W, 146–329 m; 18°13’15’’ N, 65°56’45’’ W, 439 m) (Fraser 1937).

Figures

FIGURE 4. SEM study of Callicarpa gracilis Fewkes, 1881, unbranched morphotype (part). A. Portion of stem, showing its fascicled condition. B. Portions of cladia. C. Two cladial internodes. D. Whole phylactocarp. E, F. Proximal part of a phylactocarp at different magnifications. All from sample MNHN-IK-2015-617. Scale bars: C = 100 µm; B = 200 µm; A, F = 500 µm; E = 1 mm; D = 2 mm.