Ektraleptochelia phoxops, Bamber, Roger N. & Marshall, David J., 2015

Bamber, Roger N. & Marshall, David J., 2015, Tanaidaceans from Brunei, V. The Leptocheliidae (Crustacea: Peracarida: Tanaidacea), with four new species, Zootaxa 3948 (3), pp. 342-360 : 356-359

Ektraleptochelia phoxops sp. nov.

Figs 8–9

Material: Holotype. Female with oostegites, ( NHMUK 2015. 2888), Station DA2, 05°54′28.5"N 114°38′23.3"E, 20 m depth, sand. March 2009.

Paratypes. Two ♀♀, three juveniles, ( NHMUK 2015. 2889 - 2893), one ♀ dissected on microslide, ( NHMUK 2015. 2894), Station DA2; one ♀ (not retained), sample DA1; all station DA, details as for holotype.

Description of female. Body ( Fig. 8 A) slender, about nine times as long as wide, holotype 4.1 mm long. Cephalothorax subrectangular, as long as wide, shorter than pereonites 1 and 2 together, with single mid-lateral setae, without rostrum, eyelobes ( Fig. 8 B) with anterior pointed apophysis, eyes present and black (about ten ocelli). Pereonites glabrous; pereonite 1 about half as long as cephalothorax and half as long as wide; pereonites 2 and 6 subequal, as long as cephalothorax, just longer than wide; pereonites 3 to 5 subequal in length, 2.3 times as long as pereonite 1 and about 1.3 times as long as wide. Pleon longer than pereonite 5, 0.18 times whole body length; each pleonite about four times as wide as long, with paired simple epimeral setae. Pleotelson ( Fig. 8 A, 7H) subpentangular, 1.5 times as long as last pleonite, twice as wide as long, with single midlateral setae, paired laterodistal setae and two elongate distal setae.

Antennule ( Fig. 8 C) with distinct flagellum; proximal peduncle article nearly six times as long as wide, 1.9 times as long as distal articles together, with proximal and distal tufts of penicillate setae, mid-length simple seta shorter than article width, two shorter outer simple setae and two simple distal setae; second article about twice as long as wide, one-fifth as long as first article, with three simple distal setae all shorter than article; third article 1.7 times as long as second, with three distal setae and one aesthetasc; flagellum with four simple setae.

Antenna ( Fig. 8 D) proximal article compact, with simple dorsodistal seta; second article 1.3 times as long as first, distally with slender ventral and dorsal setae; third article as long as first, with dorsodistal spine fused to article; fourth article longest, over five times as long as wide and 2.5 times as long as third, with short mid-length seta and three distal simple setae; fifth article half as long as fourth, with two distal setae; flagellum minute, with four distal setae.

Labrum ( Fig. 8 E) hood-shaped, distally coarsely setose. Left mandible ( Fig. 8 F) with wide, crenulate lacinia mobilis with bifid distal corner, coarse distal crenulation on pars incisiva, pars molaris blunt with coarse rugosity extending as marginal teeth; right mandible ( Fig. 8 G) similar but without lacinia mobilis, pars incisiva distally bifid and with five coarse marginal crenulations. Labium ( Fig. 8 H) wide, bilobed, distally finely setose. Maxillule ( Fig. 8 I) endite with ten distal spines and dense outer and medial distal marginal setae, palp with two distal setae. Maxilla ( Fig. 8 I) simple, naked. Maxilliped ( Fig. 8 J) palp first article naked, second article with three inner setae, one outer seta, sand distal seta exceeding tip of third palp article; third article with six inner marginal setae and three distal submarginal setae; fourth article with distal row of four simple setae and one mesial and two outer subdistal setae; basis with four distal seta; endites ( Fig. 8 J) distally with outer simple seta, two rounded spatulate spines and one rounded inner blunt spine. Epignath not recovered.

Cheliped ( Fig. 9 A) basis 2.6 times as long as wide, naked; merus triangular with two ventral setae; carpus about three times as long as wide, with three ventral setae and three shorter dorsal marginal setae; propodus 1.5 times as long as wide, with inner distal “comb” of one shorter and one longer setae with adjacent microtrichia, outer seta at base of dactylus; fixed finger with four ventral setae and three setae adjacent to slightly crenulate cutting edge; dactylus with inner proximal seta.

Pereopod 1 ( Fig. 9 B) longer than other pereopods, coxa with seta; basis sinuous, nearly four times as long as wide, with single dorsoproximal simple seta; ischium compact with one ventral seta; merus one-third as long as basis, with outer distal seta; carpus as long as merus, with dorsal seta as long as carpus, two fine distal setae; propodus twice as long as carpus, with three subdistal dorsal setae and one subdistal ventral seta; dactylus slender with proximal seta, extending into shorter slender unguis 0.9 times as long as dactylus, the two together 1.7 times as long as propodus. Pereopod 2 ( Fig. 9 C) more compact than pereopod 1; basis 3.4 times as long as wide, with dorsoproximal simple seta; ischium with one ventral seta; merus 0.3 times as long as basis, with ventrodistal seta; carpus as long as merus, with ventrodistal seta; propodus 1.5 times as long as carpus, with two dorsal subdistal setae and one ventral subdistal spine; dactylus and short unguis curved, together 0.4 times as long as propodus. Pereopod 3 ( Fig. 9 D) similar to pereopod 2, but merus apparently naked, carpus with additional distal seta.

Pereopod 4 ( Fig. 9 E) basis stout, 2.3 times as long as wide, naked; ischium with two ventrodistal setae; merus 0.3 times as long as basis, with paired ventrodistal spines; carpus 1.5 times as long as merus, with two outer, one ventral and one inner distal spines; propodus 0.8 times as long as carpus, with two finely-denticulate ventrodistal spines, and three dorsodistal setae, two as long as dactylus, third seta finely plumose; dactylus and unguis not fused, 0.6 times as long as propodus. Pereopod 5 ( Fig. 9 F) as pereopod 4, but basis with ventral penicillate seta, propodus with three simple setae. Pereopod 6 ( Fig. 9 G) as pereopod 5, but propodus with two additional plumose setae.

Pleopods ( Fig. 8 L) all alike, all setae plumose; basis naked, endopod with inner seta and ten marginal and one separated proximal setae; exopod with seventeen marginal and one separated proximal setae.

Uropod ( Fig. 9 H) biramous, basis naked; exopod of one segments, as long as proximal endopod segment, setose as figured; endopod of six segments, distal segments slender.

Etymology. From the Greek phoxos – pointed, and ops – eye (noun in apposition).

Remarks. The characterizing features of Ektraleptochelia phoxops sp. nov. and its distinction from other catenariins are discussed under remarks for the genus above. The pointed apophysis on the eye (after which the species is named) is also unusual, but may not be a generic character.

Figures

FIGURE 8. Ektraleptochelia phoxops gen. et sp. nov., A, holotype female, dorsal; B, left eye, dorsal; C, antennule; D, antenna; E, labrum; F, left mandible; G, right mandible; H, labium; I, maxillule and maxilla; J, maxilliped; K, maxilliped endite; L, pleopod (most setae shown only by their bases, plumosity of all seta omitted). Scale line = 1.0 mm for A, 0.15 mm for B to L.

FIGURE 9. Ektraleptochelia phoxops gen. et sp. nov., A, right cheliped; B, pereopod 1; C, pereopod 2; D, pereopod 3; E, pereopod 4 with detail of propodal spine; F, pereopod 5; G, pereopod 6; H, left uropod and part of pleotelson. Scale line = 0.2 mm.