Gonodactyloideus tricarinatus, Ahyong, 2002

Ahyong, Shane T., 2002, Stomatopoda (Crustacea) from the Marquesas Islands: results of MUSORSTOM 9, Zoosystema 24 (2), pp. 347-372 : 352-355

Gonodactyloideus tricarinatus n. sp. ( Fig. 4 )

HOLOTYPE. — Eiao, stn CP1285, 7°52.7’S, 140°36.4’E, 91 m, 07.IX.1997, tl 24 ( MNHN).

ETYMOLOGY. — Named tricarinatus for the three middorsal carina on the telson.

DIAGNOSIS. — Ocular scales broader than high, flattened, separate. Rostral plate with acute anterolateral angles; lateral margins strongly divergent anteriorly; median spine longer than base. Telson with three unarmed mid-dorsal carinae in addition to carinae of primary teeth; carina of intermediate tooth not extending anteriorly beyond posterior quarter of marginal carina.

MEASUREMENTS. — Female holotype tl 24, cl 5.2, A2 scale 2.4, A1 peduncle 3.4, AS 5 width 3.9.

DISTRIBUTION. — Known only from the type locality.

DESCRIPTION

Cornea expanded laterally, flattened dorsally, broader than stalk, extending anteriorly to end of antennal peduncle segment 2. Ophthalmic somite anterior margin with median spinule. Ocular scales relatively narrow, but broader than high, flattened, separate.

A1 peduncle 0.66cl. A1 somite dorsal processes low, truncate, with low truncate lobe at A1 peduncle articulation. A2 protopod without papillae; with fixed laterally flattened dorsal projection and anteriorly directed ventral spine. A2 scale 0.47cl.

Rostral plate slightly broader than long; anterolateral angles acute; lateral margins strongly divergent anteriorly; apical spine longer than base.

Raptorial claw propodus with long movable proximal spine; opposable margin sparsely pectinate proximally.

Mandibular palp 3-segmented. MXP1-5 each with epipod.

TS6-7 with truncate lateral margins; margin of TS6 slightly broader than TS7. TS8 lateral margin obtusely rounded; sternal keel obsolete.

AS 1-5 unarmed posterolaterally. AS 6with armed SM, IMand LTcarinae; without ventrolateral spine anteri- or to uropodal articulation margin. AWCLI748.

Telson as long as broad, with three pairs of primary teeth; with 20 SM denticles either side of midline; with three unarmed mid-dorsal carinae in addition to carinae of primary teeth; MD carina with proximal pit, apex blunt, unarmed posteriorly; accessory MD carinae obsolete, forming short “anchor”; carina of IM tooth not extending anteriorly beyond posterior quarter of MG carina; ventral surface smooth, without carinae or tubercles.

Uropodal exopod distal segment outer margin with 10 or 11 movable spines and fixed distal spine; endopod with dorsal carina laterally, entire margin with single row of setae.

Colour in alcohol

Almost completely faded. Eye stalks with longitudinal pale green stripes, flanked by dark chromatophores. Carapace and antennular somite with scattered chromatophores, most concentrated anteriorly. Rostral plate with pink apex and pair of orangish marks basally, extending onto anteri- or margin of carapace. Raptorial claw with dactylus and upper margin of meral depression pink. Thoracic and abdominal somites with sparsely scattered chromatophores dorsally.

REMARKS

Gonodactyloideus tricarinatus n. sp. differs from the only other species in the genus, G. cracens ( Manning, 1984) , in bearing sharper anterolateral angles on the rostral plate, the ocular scales are slightly broader and there are only three mid-dorsal carinae on the telson, of which none are posteriorly armed. The number of mid-dorsal carinae on the telson is diagnostic for several gonodactylid genera ( Manning 1995), but in this case variation in the number of carinae resembles variation between some species of Gonodactylellus , such as Gonodactylellus erdmanni and Gonodactylellus affinis . In Gonodactylellus affinis , the anterior submedian carinae are relatively long and all five mid-dorsal carinae are usually armed (as in G. cracens ), whereas in Gonodactylellus erdmanni , the anterior submedian carinae are short or obsolete and the median carina is usually unarmed posteriorly (as in Gonodactyloideus tricarinatus n. sp.).

Of the currently recognized gonodactylid genera, Gonodactyloideus most closely resembles Gonodactylellus in the relatively narrow ocular scales, general telson shape and absence of lobes between the terminal spines of the uropodal protopod. Unlike most gonodactylids that occupy the intertidal and shallow sublittoral zones, both species of Gonodactyloideus occur in relatively deep water: 80-107 m for G. cracens ( Manning 1984; Moosa 1986) and 91 m for G. tricarinatus .

Family ODONTODACTYLIDAE Manning, 1980

Figures

FIG. 4. — Gonodactyloideus tricarinatus n. sp., tl 24 mm (holotype); A, anterior cephalon, dorsal; B, eye, right dorsal; C, raptorial claw, right lateral; D, TS5-8, AS1, lower right lateral; E, AS5-6, telson and uropod, dorsal; F, telson, right lateral. Scale bar: 1 mm.