Staurotheca juncea (Vanhöffen, 1910)

Cantero, A. L. Peña & Vervoort, W., 2003, Species of Staurotheca Allman, 1888 (Cnidaria: Hydrozoa: Sertulariidae) from US Antarctic expeditions, with the description of three new species, Journal of Natural History 37 (22), pp. 2653-2722 : 2691-2693

Staurotheca juncea (Vanhöffen, 1910)

(figure 11; table 3)

Selaginopsis juncea Vanhöffen, 1910: 332 , figure 45a, b; Peña (Cantero) et al., 1996: 8.

Thuiaria juncea: Blanco, 1994a: 160 ; 1994b: 195.

Not Thuiaria affinis : Stepan’yants, 1972: 72 [= S. pachyclada (Jäderholm, 1904) ].

Not Thuiaria juncea : Stepan’yants, 1979: 94, pl. 18 figure 4, pl. 24 figures A, V. [= S. pachyclada (Jäderholm, 1904) ].

Not Staurotheca juncea: Peña Cantero et al., 1997: 357–359 , figure 6 [= S. pachyclada (Jäderholm, 1904) ].

Not Staurotheca juncea: Peña Cantero and García Carrascosa, 1999: 212 et seq.; Peña Cantero et al., 1999: 160 (in part).

Hydrotheca

Length of abcauline wall 800–820 Length of free adcauline wall 30–50 Length of adnate adcauline wall 1000–1050 Length of adcauline wall 1050–1080 Diameter at rim 250–260 Maximum diameter 350–360 Diameter at diaphragm 330–340

Remarks. We have re-examined part of the syntype of Selaginopsis juncea Vanhöffen, 1910 and, as has already been pointed out by Vanhöffen (1910), it is characterized by the unbranched stems and the arrangement of the hydrothecae in verticils of six hydrothecae (cf. table 6), forming 12 longitudinal rows (figure 11A). On the other hand, the hydrothecae are thin (figure 11A–C), having practically the same diameter along their entire length (they only widen slightly towards the base), are completely sunken into the branches (figure 11A, D), and, as figured by Vanhöffen, but not mentioned in his description, the hydrothecae are provided with two strong abcauline protuberances pointing into the hydrothecal lumen (i.e. a mushroom-shaped diaphragm) (figure 11A–C). However, contrary to Vanhöffen’s description, we did not observe cusps at the hydrothecal aperture. Stepan’yants (1979) already indicated that such cusps could be due to hydrothecal renovations, frequent in the type material examined, giving rise to an elevation of the abcauline side of the hydrothecal aperture (figure 11D).

The presence of a mushroom-shaped diaphragm, along with hydrothecal shape and unbranched stems, necessitates the reassignment of certain material previously referred to Vanhöffen’s species, as it is characterized by branched stems, by hydrothecae with a constriction at about half their length, greatly widening basally, and by lacking a mushroom-shaped diaphragm. All this material, i.e. that studied by Stepan’yants (1972, 1979) and Peña Cantero et al. (1997), is here considered to be conspecific with S. pachyclada (Jäderholm, 1904) for reasons outlined in remarks on that species.

Ecology and distribution. Staurotheca juncea was found at a depth of 385 m at Gauss Station, Davis Sea, 65°21∞S, 86°06∞E (Vanhöffen, 1910). It must be considered, at least for the present, as endemic to East Antarctica.