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

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Symplectoscyphus commensalis Vervoort, 1993


Symplectoscyphus commensalis Vervoort, 1993 

Fig. 17View Fig 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 073103View Materials; MNHN-IK-2015-399GoogleMaps  .


A small species, with minute hydrothecae resembling those of S. ralphae Vervoort, 1993  through their shape and size (compare Fig. 17FView Fig 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. 17GView Fig with Galea 2016: fig. 10U–V).


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

? Symplectoscyphus elongatulus Galea  , sp. nov.

Figs 16BView Fig, 17View Fig H–J; Tables 8, 10


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.


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


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.GoogleMaps 


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.


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.


Only known from off New Caledonia (present study).


National Museum of Kenya














Symplectoscyphus commensalis Vervoort, 1993

Galea, Horia R. & Schuchert, Peter 2019

Symplectoscyphus commensalis

Vervoort W. 1993: 247