Scherocumella boxshalli, Corbera, 2004

Corbera, Jordi, 2004, A new species of Scherocumella (Crustacea, Cumacea) from a coral lagoon of Lifou, New Caledonia, Zoosystema 26 (1), pp. 65-71 : 66-69

Scherocumella boxshalli n. sp.

( Figs 1-3 )

TYPE MATERIAL. — New Caledonia. Loyalty Islands, Lifou, coral lagoon, Bay of Wadra , 1 m depth, white coral sand, 21°6.0’S, 167°24.7’E, 20.X.2000, G. A. Boxshall coll. Holotype: ovigerous dissected on 2 slides (MNHN-Cu981). Paratypes: 1 adult dissected on 2 slides (MNHN-Cu982) ; 2 and 1 ovigerous (MNHN-Cu983); 1 ovigerous and 2 (ICM-CUM0035).

ETYMOLOGY. — Named in honour of Geoff A. Boxshall (London) who kindly offered this material to me, and in recognition of his wide contribution to the knowledge of crustaceans.

DESCRIPTION

Adult female, total length 1.2 mm. Carapace twice as long as high and more than one third of total body length; covered by scales near the lateral margin, which disappear dorsally; with some club-shaped setae clustering in small groups near middorsal line. Pseudorostral lobes meeting in front of head. Eyes paired, dorsolateral, with well developed lenses and pigmented. Anterolateral angle slightly acute. Pereon with five somites visible dorsally and laterally. Pleon slightly shorter than the rest of body, without free telson. Exopodites on third maxiliped and first and second pereopods.

Antenna 1 peduncle article 1 as long as other two combined; article 2 shorter than 3, with a small tubercle and two setae on distal outer corner; accessory flagellum minute, main fagellum twosegmented with two distal aesthetascs. Mandible, pars incisa with three teeth, lacinia mobilis, five spine-like setae between pars incisa and pars molaris, pars molaris truncated. Maxilla 1 protopod with robust setae of decreasing length, palp longer than protopod and with two simple filaments. Maxilla 2 with the endites exceeding the protopod, with simple setae on its top margin. Maxiliped 2 with a long plumose seta in distal inner corner of basis; ischium very short; merus with a rounded tubercle produced backwards; carpus, the longest segment except basis, with setules and a plumose seta on inner margin; dactylus with a long distal claw. Maxilliped 3 basis longer than the three following segments togeth- er, produced distally reaching half length of merus, with two long plumose setae; merus slightly produced distally with a long plumose seta; carpus shorter than propodus, with a long plumose seta; dactylus half length than propodus. Pereopod 1 basis shorter than the three following segments together, with some simple setae on its distal margin; carpus as long as propodus and twice as dactylus. Pereopod 2, basis as long as the following four segments together; ischium very short; carpus longer than propodus; dactylus as long as carpus, with three distal spine-like setae. Pereopod 5, basis about one third of the entire pereopod, carpus longer than propodus.

Peduncle of uropod slightly shorter than the last pleonite, as long as exopod and shorter than endopod. Exopod longer than its distal seta. Endopod with hyaline serration on the inner margin, with two terminal flagellate spine-like setae.

Adult male total length 1.22 mm. Carapace more than one third of total length, with few clubshaped setae. Pseudorostrum directed forward and shorter than in female. Eyes paired, located dorsolaterally, pigmented and more developed than in female. Exopodites on third maxiliped and from first to fourth pereopods.

Antenna 2 peduncle five-segmented, with sensorial setae on articles fourth and fifth, flagellum very long reaching beyond the fifth pleonite. Maxilliped 1, carpus with six multidenticulated flattened setae and a row of simple setae on the inner margin; propodus with a long plumose seta; dactylus rounded with two short apical setae. Maxilliped 3, basis longer than rest of limb, slightly produced distally with two long plumose setae on the process and two other on the distal margin; merus and carpus with a long plumose seta; propodus twice length of dactylus. Pereopod 1, basis strong and longer than the three following segments combined; propodus shorter than carpus; dactylus half length of propodus. Pereopod 2, basis strong and as long as the rest of appendage; dactylus 1.5 times longer than propodus, with a short simple seta on each margin and four terminal simple setae, one longer than dactylus. Pereopods 3 and 4 with strong basis, carpus longer than propodus. Pereopod 5, basis shorter than one third of total appendage length, carpus twice as propodus.

Peduncle of uropod as long as the last pleonite with hyaline serration on the inner margin, and longer than the rami. Exopod shorter than its distal seta. Endopod with hyaline serration on the inner margin, with one distal and two terminal flagellate spine-like setae.

REMARKS

Scherocumella boxshalli n. sp. agrees with the genus diagnosis in having anterolateral angle in female acute but not projecting, pseudorostral lobes united in front of head and second article of the first antenna shorter than the third. However, the uropod peduncle is not longer than the last abdominal somite. Petrescu (1997a) suggests adding characteristics of mouth appendages after the observations made on two species, S. fagei Petrescu, 1997 and S. nasuta (Zimmer, 1914) : lacinia mobilis of mandible with four teeth and maxilla 1 with only one filament on the palp. However, these characteristics were not observed on S. boxshalli n. sp.

The genus Scherocumella has a combination of characters from the genera Nannastacus and Cumella Sars, 1865 and there may exist a gradation between the two genera. It is suggested including the new species in the genus Scherocumella because of the characteristics mentioned above and the general shape of the carapace, which is more similar to the genus Cumella than the genus Nannastacus .

Scherocumella boxshalli n. sp. is closely related to S. micronodosa Mühlenhardt-Siegel, 1996 by its short uropod peduncle but differs from it by lacking tubercles and minute nodules on the carapace and by having a first pereopod reaching beyond the tip of pseudorostrum.

Figures

FIG. 1. — Scherocumella boxshalli n. sp., Lifou, Loyalty Islands, New Caledonia, adult holotype (MNHN-Cu981); A, whole body in lateral view; B, antenna 1; C, mandible; D, maxilla 1; E, maxilla 2; F, maxilliped 2; G, maxilliped 3; H, pereopod 1; I, pereopod 2; J, pereopod 5; K, uropod. Scale bars: 100 µm.

FIG. 2. — Scherocumella boxshalli n. sp., Lifou, Loyalty Islands, New Caledonia, SEM photos, adult; A, carapace in lateral view; B, carapace in dorso-lateral view; C, microstructure of integument near the lateral margin showing the scales and two club-like setae; D, microstructure of integument near the middorsal line, where the scales are not visible and the club-like setae are more abundant. Scale bars: A, B, 200 µm; C, 20 µm; D, 50 µm.

FIG. 3. — Scherocumella boxshalli n. sp., Lifou, Loyalty Islands, New Caledonia, adult paratype (MNHN-Cu982); A, whole body in lateral view; B, maxilliped 1; C, maxilliped 3; D, pereopod 1; E, pereopod 2; F, pereopod 3; G, pereopod 4; H, pereopod 5; I, uropod. Scale bars: 100 µm.