Symplectoscyphus paucicatillus, Galea, 2016

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 : 46-47

Symplectoscyphus paucicatillus sp. nov.

urn:lsid:zoobank.org:act:B00A7B9A-265C-48D9-BDDB-71DB49EA7DE7

Fig. 10 W–Z; Table 7

Diagnosis

Symplectoscyphus with monosiphonic stems; branching pseudodichotomous, occurring at irregular intervals; internodes moderately long, slender, geniculate; hydrothecae long, tubular, sigmoid in shape; gonothecae transversely ribbed distally, undulated basally, with trumpet-shaped apical tube.

Etymology

From the Latin words pauci, -ōrum, meaning a few, and cātillus, -i, meaning small dish(es), making reference to the shape of the gonotheca, which resembles several stacked dishes.

Material examined

Holotype

BATHUS 4 : Stn. DW 923, ca 2.8 cm high colony, bearing 3 fully formed and one incipient gonotheca (MNHN-IK-2012-16596).

Paratypes

BATHUS 4: Stn. DW923, two sterile colonies 2 and 3 cm high (MNHN-IK-2012-16597).

Description

Colonies up to 3 cm high arising from creeping, branching hydrorhiza. Stems monosiphonic throughout, composed of a long (up to 1.4 cm), lower, ahydrothecate part, and an upper and longest part bearing hydrothecae. Perisarc rather thick and straw colored, thinning out gradually towards tips of colonies; basally a little tortuous, rapidly becoming straight and smooth. Hydrothecate part divided into rather poorly indicated internodes by means of oblique constrictions of the perisarc slanting in alternate directions; each internode moderately long, slender, distinctly geniculate, bearing a hydrotheca distally. Branching pattern pseudodichotomous; side branches arising at irregular intervals from slightly below a hydrotheca, the latter becoming axillar ( Fig. 10X); structure identical to that of stem; first internode not significantly longer compared to subsequent ones; up to 2 nd order side branches, and all in roughly one plane, giving the colony a flabellate appearance. Hydrothecae originating at very acute angles with the axis of corresponding internode; long, tubular, slightly sigmoid (facing outward basally and upwards distally); adaxial wall adnate for about ½ its length; aperture with three pointed, triangular cusps separated by moderately deep embayments; adaxial cusp produced adaxially; opercular apparatus usually lost; renovation of margin common. Gonothecae borne on both the main stem and side branches, arising usually from below the hydrothecal bases, occasionally from the axil formed by free adaxial wall with next internode; body elongated ovoid, provided distally with 2–3 broad, conspicuous, transverse ribs, and undulated basally, where it tapers to an indistinct pedicel; apical part a flattened plateau from the center of which arises a short trumpet-shaped tube; sex of gonothecae apparently female, judging from the remains of soft tissues (presence of a spherical body, likely an oocyte).

Remarks

The hydrothecae of this species resemble those of other congeners, but there are points of difference which allow their specific separation, as follows: 1) S. amoenus Vervoort &Watson, 2003 is a species with fascicled stems, its hydrothecae are deeper (755–920 µm, compared to 590–625 in the present material), and its gonothecae have undulated walls ( Vervoort & Watson 2003); 2) S. amphoriferus (Allman, 1877) has comparatively slender hydrothecae (judging from the size of their apertures), and its gonothecae are pear-shaped, with “eleven raised transverse ridges and a slender terminal neck” ( Millard 1977); 3) S. effusus Vervoort, 1993 , but this is a comparatively smaller species (compare Fig. 10G and 10Y); 4) S. macrocarpus (Billard, 1918) , has more slender [according to the size of their apertures (see Billard 1925b; Schuchert 2003)] and shorter hydrothecae (420–470 µm); in addition, its gonothecae (of both sexes) are characteristically amphora-shaped ( Billard 1925b); 5) S. pedunculatus ( Billard, 1919) has longer, more slender, and less adnate hydrothecae ( Billard 1925b; Vervoort 1993).

Geographical distribution

New Caledonia.