Leptochelia aff. minuta Dana

Bamber, Roger N., 2006, Shallow water tanaidaceans (Crustacea: Peracarida: Tanaidacea) from New Caledonia and the Loyalty Islands, Zootaxa 1108, pp. 1-21 : 12-15

Leptochelia aff. minuta Dana

Fig 6

Material: 2 males ( MNHN.Ta898), sample LF3 ‘83’, Baie de Santal, Loyalty Islands, 20º07.27’S 167º07.34’E, 12 m depth on red algae.

Description of male: body glabrous ( Figure 6 A) 5.5 times as long as wide, holotype 3 mm long; cephalon subrectangular, 1.2 times as long as wide, with bulbous eyes bearing prominent ocelli with black pigment. Pereonite 1 shortest, one­third as long as cephalon, pereonites 2 and 3 subequal, 1.5 times as long as pereonite 1; pereonites 4 to 6 subequal, twice as long as pereonite 1; pleon as long as cephalon, with five distinct pleonites; pleotelson twice as wide as long.

Antennule ( Figure 6 B) two­thirds as long as body, first peduncle article longest, with simple dorsodistal seta; second peduncle article half length of first, with inner and outer strong distal setae; third peduncle article one­third length of second; flagellum of 13 segments, respectively with 3, 3, 3, 3, 4, 4, 4, 4, 3, 3, 3, 3 and 2 aesthetascs ventrally; distal article with two distal setae.

Antenna ( Figure 6 C) of six articles; proximal peduncle article wider than long; article 2 twice as long as article 1, with dorsodistal and ventrodistal spines; article 3 just longer than first, naked; fourth article 3 times as long as third with five simple and one plumose sensory distal setae; fifth article twice as long as third with two distal setae; sixth article minute, with two distal setae.

Mouthparts atrophied.

Cheliped ( Figure 6 E) basis short, 1.3 times as long as wide; merus 0.6 times as long as basis, with single ventral, two subdistal and two distal setae; carpus 2.5 times as long as basis, 4 times as long as wide, one third as long as body with two ventral setae in distal third; propodus palm 2.5 times as long as wide, as long as fixed finger, the two together longer than carpus, palm with row of ten short spines near base of dactylus; dactylus sickle­shaped, longer than fixed finger; both fingers with short terminal spine.

Pereopod 1 ( Figure 6 F) longest, basis slender, 6 times as long as wide, naked; ischium naked; merus and carpus subequal, 0.4 times as long as basis, merus with single dorsodistal seta, carpus with dorsal, lateral and ventral distal setae. Propodus nearly twice as long as carpus, with dorsodistal and ventrodistal setae; dactylus longer than unguis, together 0.8 times as long as propodus.

Pereopods 2 ( Figure 6 G) and 3 similar to, but smaller than, pereopod 1, basis with single middorsal seta, merus with single dorsodistal and ventrodistal setae, carpus with dorsodistal seta and ventrodistal stout spine; propodus with ventrodistal blunt spine. Pereopod 4 ( Figure 6 H) with stouter basis, 2.5 times as long as wide with ventrodistal seta; ischium with two ventrodistal setae; merus with two ventrodistal spines; carpus with curved inner and ventral distal spines; propodus slender, with ventrodistal blunt spine and two dorsodistal setae; dactylus plus unguis a fused, curved claw.

Pereopod 5 as pereopod 4 but without dorsodistal setae on propodus.

Pereopod 6 as pereopod 4, but propodus ( Figure 6 I) with four dorsodistal setae.

Uropod ( Figure 6 D) with stout basis bearing three inner and longer outer distal setae; exopod of two subequal segments with two distal setae longer than exopod; endopod of six distally setose segments.

Female unknown.

Remarks: the Leptochelia minuta aggregate has been the subject of taxonomic confusion: the species were historically described on the basis of the male morphology, without reasonable understanding of intraspecific variability, nor of the fundamental morphology of the less specialized females. Lang (1973) analyzed the variability in numerous male specimens at his disposal, principally on the basis of chela morphology.

There are currently a probable six valid taxa in this aggregate, L. minuta Dana , recorded from the littoral zone of Polynesia and possibly the Red Sea; L. erythraea (Kossman) , accorded the same distribution, but probably either the Red Sea species or a synonym of L. minuta ; L. mirabilis Stebbing , recorded from the Gulf of Manaar, Philippines, and New Zealand, at depths of 0–366m (probably more than one taxon), L. longimana Shiino , from 4–14 m depth off South Viet­Nam (possibly a synonym of L. mirabilis ), L. forresti (Stebbing) from shallow waters in the Caribbean, and a shallowwater West Australian species with distinctive antennule proportions and large hyposphenia (Bamber in press). The statuses of L. tenuicola Makkaveeva from 7 m depth off Cuba and of L. ignota (Chilton) from Sydney Harbour are unclear.

The present material is unusual in having the chela fingers subequal to the palm, and that palm distally nearly half as wide as its length. Together with the proportions of the antennule peduncle articles, it does not resemble any of the described species. Full analysis of this taxon must await the discovery of females.

Figures

FIGURE 6. Leptochelia aff. minuta, male: A, body, dorsal; B, antennule; C, antenna; D, uropod; E, cheliped; F, pereopod 1; G, pereopod 2; H, pereopod 4; I, distal articles of pereopod 6. Scale line = 1 mm for A, 0.4 mm for B, C and E; 0.2 mm for D and F to I.