Symplectoscyphus commensalis Vervoort, 1993

Galea, Horia R. & Schuchert, Peter, 2019, Some thecate hydroids (Cnidaria: Hydrozoa) from off New Caledonia collected during KANACONO and KANADEEP expeditions of the French Tropical Deep-Sea Benthos Program, European Journal of Taxonomy 562, pp. 1-70 : 48-50

Symplectoscyphus commensalis Vervoort, 1993

Fig. 17 F–G

Symplectoscyphus commensalis Vervoort, 1993: 247 , figs 56C–F, 57, 58A–E.

Material examined

PACIFIC OCEAN • female colony with stems up to 1 cm high on stem of sertulariid hydroid; off New Caledonia, stn DW4670; 22°58′ S, 167°24′ E; 680– 612 m; 12 Aug. 2016; KANACONO leg.; one stem was used for DNA extraction, DNA 1389; voucher MHNG-INVE- 120850; barcode identifier MK 073103 ; MNHN-IK-2015-399 .

Remarks

A small species, with minute hydrothecae resembling those of S. ralphae Vervoort, 1993 through their shape and size (compare Fig. 17F with Galea 2016: fig 10Q–T). Unlike S. commensalis that forms irregularly-branched colonies (up to 2 nd order branches observed), the latter builds regularly-pinnate colonies. In addition, their respective gonothecae are different [compare Fig. 17G with Galea 2016: fig. 10U–V).

Distribution

Only known from off New Caledonia ( Vervoort 1993; present study).

? Symplectoscyphus elongatulus Galea , sp. nov.

urn:lsid:zoobank.org:act:E30569B6-8BC4-4B3C-8E84-8EC1A2300839

Figs 16B , 17 H–J; Tables 8 , 10

Diagnosis

Sparingly-branched symplectoscyphid forming delicate, coplanar colonies, with erect, monosiphonic stems. Internodes long, slender, distinctly geniculate, each carrying distally a hydrotheca; the latter long, slightly conical, smooth-walled, adnate for ⅓, abaxial wall straight or nearly so, free adaxial wall imperceptibly convex proximally, and distinctly concave below aperture; adaxial cusp produced, slightly everted; eight internal, submarginal projections of perisarc. Gonothecae unknown.

Etymology

From the Latin ‘ ēlongo, -āvi, -āre ’, meaning ‘to lengthen’, with the apposition of the suffix ‘ -ulus, -ula, ulum ’, as a diminutive, to characterize the shape of the internodes of this delicate, straggling species.

Material examined

Holotype

PACIFIC OCEAN • a 5.1 cm high colony without gonothecae; off New Caledonia, stn DW5010; 22°10′ S, 159°03′ E; 290–820 m; 19 Sep. 2017; KANADEEP leg.; MNHN-IK-2015-463.

Description

Colony erect, 5.1 cm high, arising from creeping hydrorhiza. Stem monosiphonic, flaccid, unable to support itself when out of liquid; basal 1.6 cm ahydrothecate, with smooth perisarc; remainder of stem divided into regular internodes by means of indistinct oblique nodes slanting in alternate directions; internodes distinctly geniculate, long, each bearing distally a hydrotheca; branching sparse, irregular: only two side branches, neither branching further, occur in the present specimen; they are given off laterally and in opposite directions, from below the bases of two distant stem hydrothecae, and are coplanar. Hydrothecae long, slightly conical, adnate for ⅓ or less to their corresponding internodes; abaxial wall straight for most of its length, imperceptibly convex distally; free adaxial wall slightly sigmoid, convex for most of its length, then concave towards aperture; aperture three-cusped, adaxial cusp slightly produced, latero-abaxial cusps less prominent, with rounded tips, separated by wide, shallow embayments; operculum composed of three triangular flaps meeting centrally to form a pyramidal roof; 8 internal, submarginal projections of the perisarc: one minute adaxial, two pairs of latero-adaxial, one large abaxial, and two latero-abaxial. Gonothecae not observed.

Remarks

Only a restricted number of congeners display a combination of long, slender, geniculate internodes and weakly-adnate hydrothecae, namely: S. amphoriferus Allman, 1877 ( Millard 1977; Schuchert 2001), S. bathyalis Vervoort, 1972 (original account, Calder & Vervoort 1998), S. dentiferus (Torrey, 1902) ( Nutting 1904) , S. effusus Vervoort, 1993 (original account, Galea 2016), S. macrocarpus (Billard, 1918) (original account, Billard 1925), S. minutus ( Nutting, 1904) (original account), S. naumovi Blanco, 1969 ( Peña Cantero et al. 2002), S. nesioticus Blanco, 1977 (original account, Peña Cantero et al. 2002), S. paucicatillus Galea, 2016 (original account), S. paulensis Stechow, 1923 ( Vervoort 1993; present report), S. pedunculatus (Billard, 1919) ( Billard 1925; Vervoort 1993) and S. plectilis (Hickson & Gravely, 1907) ( Millard 1977) . However, in any of these the hydrothecae do not adopt the distinctive shape met with in S. elongatulus sp. nov., and none displays submarginal, intrathecal cusps.

Through its Sertularella -like hydrothecae, provided with only three marginal cusps, the present species comes close to? Symplectoscyphus acutustriatus sp. nov. (see above), whose systematic position is discussed in the ‘Molecular study’ section.

Distribution

Only known from off New Caledonia (present study).

Figures

Fig. 17. A–E.? Symplectoscyphus acutustriatus Galea, sp. nov., portion of stem with side branch (A, from sample MNHN-IK-2015-460); hydrothecae without (B) and with (C) internal, submarginal cusps, aperture in apical view (D), portion of colony with gonotheca (E), all from sample MNHN- IK-2015-461. — F–G. Symplectoscyphus commensalis Vervoort, 1993, portion of colony with internodes and hydrothecae (F), gonotheca(G), both from sampleMNHN-IK-2015-399.— H–J.? Symplectoscyphus elongatulus Galea, sp. nov., portion of stem with proximal part of cladium (H), hydrotheca (I), apical view of aperture showing submarginal, intrathecal cusps (J), all from sample MNHN-IK-2015-463. — K–M. Symplectoscyphus paulensis Stechow, 1923, colony fragment (K), hydrotheca (L), gonotheca (M), all from sample MNHN-IK-2015-393. — N–O. Symplectoscyphus cf. tropicus (Hartlaub, 1901), portion of colony (N), hydrotheca (O), both from sample MNHN-IK-2015-394. Scale bars: A, H, K, N = 1 mm; B–C, E–G, I, L–M, O = 500 µm; D, J = 100 µm.

Fig. 16. A.? Symplectoscyphus acutustriatus Galea, sp. nov., holotype colony, MNHN- IK-2015-460. — B.? Symplectoscyphus elongatulus Galea, sp. nov., holotype colony, MNHN- IK-2015-463. — C. Symplectoscyphus paulensis Stechow, 1923, colonies from sample MNHN- IK-2015-393. — D. Symplectoscyphus cf. tropicus (Hartlaub, 1901), colony from sample MNHN-IK-2015-394. — E. Tuberocaulus scorpioides (Vervoort, 1993) gen. et comb. nov., colony from sample MNHN-IK-2015-400. — F–G. Zygophylax niger Galea, sp. nov., holotype colony (F) and detail of its coppinia (G) from sample MNHN-IK-2015-478. Scale bars: A, G = 5 mm; B–E = 1 cm; F = 2 cm.