Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

166
Fig. 25. Diphasia digitalis (Busk, 1852); station 72. A. Part
of stem and hydrocladium. B. Gonotheca. – Scale: A–B = 0.5
mm.
Family Sertulariidae
Diphasia digitalis (Busk, 1852)
Fig. 25.
Sertularia digitalis Busk, 1852: 393.
Desmoscyphus longitheca Allman, 1877: 26, pl. 14: figs 3–
6. – Nutting 1904: 111.
Desmoscyphus acanthocarpus Allman, 1888: 73, pl. 35: fig.
2a–c. – Nutting 1904: 111.
Nigellastrum digitale. – Mammen 1965: 57, fig. 89.
Diphasia digitalis. – Nutting 1904: 110, pl. 30: figs 2–7. –
Bale 1884: 101, pl. 9: figs 3–5. – Billard 1925b: 209. –
Vervoort 1959: 254, fig. 22. – Vervoort 1968: 37, fig. 17.
– Millard & Bouillon 1973: 67, fig. 9A. – Millard 1975:
257, fig. 85E. – Watson 2000: 14, fig. 10A–B.
Material examined:
Kei Islands Expedition stations: 18, fertile. – 67. – 68. – 71,
fertile. – 72, fertile. – 90, fertile. – 104. – 107, fertile. – 110.
Description
Colonies erect, pinnate, 3–6 cm high. Main stem
mostly unbranched, occasionally branched, with
two rows of hydrothecae. Hydrocladia alternate,
somewhat irregular in distribution and length.
Hydrothecae in opposite pairs, consecutive
pairs mostly overlapping or very close. In lower
P. SCHUCHERT
region of the stem members of a pair of hydrothecae
placed on lateral sides and not contiguous
with one another; in distal region and on hydrocladia
members of a pair placed on anterior surface
and contiguous with one another, the two
rows forming an angle that is much less than
180°. Hydrotheca about 0.8 mm deep, 0.3 mm
broad, adnate for ¾ to entire length, distal part
curved slightly away, cross section rounded in
basal part, distinctly pentagonal at distal end,
with lateral longitudinal crease lines, sometimes
also a short median crease line on abcauline wall
beginning at margin of hydrotheca, margin untoothed,
on adcauline side a broad and deep
emargination. No internal cusps or ridges. Operculum
single, large, attached to adcauline rim of
hydrotheca.
Gonothecae on stem, spindle shaped, 2 mm
long, diameter 0.6 mm, with numerous short,
stout spines in 10–12 rows, 10–12 spines per row.
Hydranths without abcauline blind-sac.
Remarks
Almost all examined colonies had characteristic
blackish pigment granules in the epidermis of the
coenosarc and the tissue covering the inside of
the hydrotheca. Bale (1884) described the colour
of the colony as grey to almost black.
Distribution
Circumglobal in tropical and subtropical waters.
Type locality: Prince of Wales Channel, Torres
Strait, Australia, 16 m.
Diphasia mutulata (Busk, 1852)
Fig. 26.
Sertularia mutulata Busk, 1852: 391.
Diphasia mutulata. – Bale 1884: 101, pl. 9: figs 6–9. –
Ritchie 1910a: 12, pl. 4: fig. 3. – Billard 1933: 16, fig. 6,
pl. fig. 4. – Watson 2000: 12, fig. 9A–G.
?Diphasia mutulata. – Thornely 1904: 118, pl. 2: fig. 6 [? =
Diphasia thornelyi Ritchie, 1909].
?Diphasia thornelyi Ritchie, 1909: 525. – Ritchie 1910a: 13,
pl. 4: figs 4–5. – Jäderholm 1919: 16, pl. 4: figs 2–3. –
Billard 1925b: 215, fig. 54.
Diphasia thornelyi. – Jäderholm 1919: 16, pl. 4 figs 2–3.
Nigelastrum mutulatum. – Stechow & Müller 1923: 468. –
Mammen 1965: 56, fig. 88.
Material examined:
Kei Islands Expedition, Tual, Kei Islands, 1–2 m, 23 Mar