Zygophylax kakaiba Campos, Marques, Puce & Pérez,

Campos, Felipe Ferreira, Marques, Antonio Carlos, Puce, Stefania & Pérez, Carlos Daniel, 2016, Zygophylax kakaiba, a new species of hydroid (Cnidaria: Hydrozoa: Zygophylacidae) from the Philippine Islands, Zootaxa 4088 (3), pp. 438-444: 439-442

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Zygophylax kakaiba Campos, Marques, Puce & Pérez

sp. nov.

Zygophylax kakaiba Campos, Marques, Puce & Pérez  , sp. nov.

Plate 1View PLATE 1 (A –F)

Material examined. Holotype: the Philippine Islands, 6°1’N, 121°28’E, 580 m, 5.vii.1889, no gonophores (ZMA Coel. 5147).GoogleMaps 

Description. Colony erect, 15 mm high, almost planar, pinnate (Pl. 1A). Main stem polysiphonic, not divided into nodes and internodes, weakly polysiphonic distally; main stem and secondary tubes associated up to distal third (Pl. 1B). Apical monosiphonic axis of colony ~3 mm, not divided into nodes and internodes. Hydrocladia sub-opposite, slightly turned towards frontal direction, arising at angles of ca. 75–80° in relation to long axis of stem; two hydrothecae between each pair of hydrocladia. Main stem and hydrocladia straight or slightly geniculate (Pl. 1C). Some proximal hydrocladia with one secondary additional tube at proximal region. Hydrothecae arranged biserially, alternate, arising at angles of ~45–50° in relation to axis. Hydrothecal aperture turned towards adcauline direction due to an adcauline abrupt torsion at hydrothecal distal third, consequently hydrothecae concave under rim; plane of aperture parallel in relation to proximal and median hydrothecal axis. Axillar hydrothecae adcauline in relation to main stem (Pl. 1D). Hydrothecae tubular, adcauline wall convex at different degrees up to distal third; abcauline wall slightly concave or almost straight, some hydrothecal walls slightly sigmoid due to a more accentuated concavity. Some hydrothecae with internal perisarcal projection arising obliquely from adcauline wall to abcauline wall, generally at proximal third (Pl. 1E). Diaphragm distinct, oblique. Pedicel short, straight, continuous to apophyses. Rim smooth, some slightly everted, up to 4 renovations, but not significantly increasing length of hydrotheca. One or two axillar nematothecae cylindrical at junction between hydrotheca and axis, but most hydrothecae without nematothecae because they commonly breake off (Pl. 1F). Rare preserved nematothecae on secondary tubes, but some circular insertion scars visible. Perisarc yellowish. Despite good preservation, no integer hydranths have been found. Gonothecae not present.

Measurements (in µm). Stem: diameter 170–300; distance between consecutive hydrothecae 150–290; distance between consecutive hydrocladia on same side 1310–1510. Hydrocladium: diameter at base 200–230; length 2340–4470. Hydrotheca: length of adcauline wall from diaphragm (measured as a straight line) 290–330; diameter at rim 120–130; diameter at diaphragm 90–100; length of pedicel (on adcauline wall) 90–180. Nematotheca: length 50–170; diameter at rim 20–25.

Etymology. In Tagalog, a native language of The Philippines, the word kakaiba  means “weird”, used here as a reference to the unique and abrupt torsion of the distal third of hydrothecae in relation to the axis towards adaxial side.

Distribution. The Philippines Islands, channel between Sulu and Bagalo islands (6°1’N, 121°28’E), at 580 m deep.