Hypocuma fragosum, Corbera, 2008

Corbera, Jordi, 2008, Deep-sea Bodotriidae (Crustacea: Cumacea) from New Caledonia, Fiji and Indonesia, Zoological Journal of the Linnean Society 152 (2), pp. 227-254 : 248-251

HYPOCUMA FRAGOSUM SP. NOV. ( FIGS 20 , 21 )

Type material: Holotype: preadult male, New Caledonia, BIOCAL, stn CP72, 22°09.02′S, 167°33.18′E, 2100–2110 m, 4.ix.1985 (MNHN-Cu1099) . Paratypes: same station as holotype, 1 preadult male, 1 preadult female, partially dissected in one slide (MNHN- Cu1100).

Diagnosis: Carapace uniformly covered by small denticles; pseudorostral lobes one-sixth carapace length. Antenna 1, main flagellum 2-articulated. Article 2 of uropod exopod three times as long as article 1.

Description: Preadult male 7.3 mm total length. Carapace ( Fig. 20A ) shorter than one-third total length, dorsal outline somewhat curved. Integument rough, covered by small triangular denticles. Pseudorostral lobes meeting in front of the eyelobe for one-sixth carapace length. Without eyes. Anterolateral margin with a row of spines, and without projection. Male with five pairs of pleopods. Pleonite 6 produced backwards between the uropods.

Antennule ( Fig. 20B ), peduncle article 1 as long as the following two articles combined; article 3 shorter than article 2; main flagellum 2-articulate, article 1 longer than twice length of article 2; with two aesthetascs; accessory flagellum rudimentary. Mouth appendages do not dissected in order to preserve the holotype.

Maxilliped 3 ( Fig. 20C ) with well-developed exopod, basis longer than rest of appendage, not expanded distally, with three long plumose setae on distal outer corner; merus slightly produced distally with a long plumose seta on the tip; carpus as long as propodus, the first with three plumose and a simple setae on inner margin and a plumose seta on distal outer corner. Pereopod 1 ( Fig. 20D ) with well-developed exopod, basis shorter than rest of appendage, with three small plumose setae distally; merus twice as long as ischium; carpus slightly longer than propodus with simple setae on both margins; dactylus half length than propodus.

Uropod peduncle ( Fig. 20E ) as long as pleonite 5, 1.2 times as long as rami. Endopod 2-articulated; article 1 more than four times as long as article 2, with seven setae on inner margin; article 2 with three setae terminally. Exopod as long as endopod; article 2 three times as long as article 1, with three setae terminally.

Preadult female. Antennule ( Fig. 21A ), peduncle article 1 as long as the following two articles combined; article 3 shorter than article 2; main flagellum 2-articulate, article 1 longer than twice length of article 2; with two aesthetascs; accessory flagellum rudimentary. Left mandible ( Fig. 21B ) with four teeth on the pars incisiva, 15 setae between pars incisiva and pars molaris. Maxillule ( Fig. 21C ) palp with two unequal filaments, inner endite with five setae, three simple, one trifid and one serrulate. Maxilla ( Fig. 21D ), endites with simple and serrate setae.

Maxilliped 1 ( Fig. 21E ) basis with four plumoserrate and two simple setae on inner margin, distally produced reaching carpus; merus with a long pappose seta on distal outer corner; carpus with five flattened one-sided serrate setae on the inner margin; propodus with three cuspidate setae on distal inner corner. Maxilliped 2 ( Fig. 21F ) basis slightly longer than rest of appendage, with two pappose setae distally; merus with two long pappose setae on inner margin and one on distal outer corner; carpus longer than merus with three short forked setae on inner margin and a long plumose seta on distal outer corner; propodus shorter than carpus, with three simple setae on inner margin.

Pereopod 2 ( Fig. 21G ) with well-developed exopod (not figured), basis slightly shorter than rest of appendage, with a small pappose seta on distal lower corner; ischium short; merus shorter than carpus; carpus with a seta on distal corner; propodus shorter than merus with a cuspidate seta on distal corner; dactylus more than three times as long as propodus, with four cuspidate setae on lower margin, one on the upper margin and three terminally (the central one lost). Pereopod 3 ( Fig. 21H ) with well-developed exopod (not figured); basis longer than rest of appendage; merus longer than ischium; carpus three times as long as merus, with a simple seta on distal corner; propodus shorter than half length of carpus, with a long simple seta on distal corner. Pereopod 4 ( Fig. 21I ) with rudimentary 2-articulate exopod, basis shorter than rest of appendage; merus longer than ischium, with a simple seta on distal corner; carpus three times as long as merus, with a simple seta on distal corner; propodus shorter than half length of carpus, with a long simple seta on distal corner. Pereopod 5 ( Fig. 21J ), basis rather shorter than rest of appendage; carpus more than three times as long as carpus; propodus with a long simple seta on distal corner.

Etymology: From the Latin fragosus meaning rough, referring to the denticulate microstructure of the integument.

Remarks: Only two species were previously known for the genus Hypocuma , H. serratifrons Jones, 1973 and H. dentatum Day, 1975 . H. fragosum differs from the first by the relative length of their uropod exopod articles, the second article being three times as long as the first in the new species. Uropods are not known in H. dentatum , which differs by its longer pseudorostrum (about one-fifth carapace length) and the presence of a row of more developed denticles on the frontal lobe. Moreover, the main flagellum of antenna 1 is always 2-articulated in H. fragosum while it is apparently 1-articulated in the females and 3-articulated in the male of H. dentatum .

Figures

Figure 20. Hypocuma fragosum sp. nov. preadult male holotype: A, whole animal in lateral view; B, antenna 1; C, maxilliped 3; D, pereopod 1; E, uropod.

Figure 21. Hypocuma fragosum sp. nov. preadult female paratype: A, antenna 1; B, left mandible; C, maxilla 1; D, maxilla 2; E, maxilliped 1; F, maxilliped 2; G, pereopod 2; H, pereopod 3; I, pereopod 4; J, pereopod 5.