Lourinia aldabraensis sp. nov.

(Figs. 20–24)

Synonym. Lourinia armata (Claus, 1866) sensu Wells & McKenzie (1973) .

Type locality. Aldabra, Indian Ocean; West Island settlement, saline tide influenced pool; cf. station 71 in Wells & McKenzie (1973) .

Type material. Holotype ♀ dissected on five slides. Allotype ♂ preserved in alcohol. Paratypes are three ♂♂ and three copepodids preserved in alcohol. Collected and preserved by K.G. McKenzie in 1968. Determined as Lourinia armata by J.B.J Wells in 1971 and deposited in the Natural History Museum (London) under registration numbers NHMUK 1972.6.14.11–15.

Description of female: Body (Fig. 20A–B) shape similar to L. aff. armata . Total body length: 844 μm. Maximum width: 178 μm. Surface of prosome, free somites and caudal rami ornamented with microspinules as figured (Figs. 20A–B, D; 23A). Spinular ornamentation of genital double-somite, third and fourth urosomites similar to that of L. aff. armata (Figs. 20B; 23A). Anal somite with one pair of sensilla dorsally; anal operculum straight, margin ornamented with setules (Fig. 20D).

Antennule. Segmentation and setation similar to those of L. aff. armata .

Antenna (Fig. 20C). Coxa ornamented with spinule rows as figured. Allobasis ornamented with spinule row as figured. Exopod 1-segmented; with two bipinnate apical setae. Endopod 1-segmented, ornamented with spinule rows as figured, lateral armature consisting of two bipinnate spines, distal armature consisting of four bipinnate spines (outer one fused basally to seta).

Mandible, maxillule, maxilla and maxilliped as in L. aff. armata .

P1 (Fig. 21A). Ornamentation of praecoxa, coxa and basis similar to that in L. aff. armata . Inner spine of basis extending beyond end of first endopodal segment. Exopod 3-segmented; distal segment with one inner seta, one apical seta and two outer spines. Endopod 2-segmented, shorter than exopod; first segment with one distally pectinate, inner seta; distal segment with two inner setae (proximal one distally pectinate) and one apical spine.

P2–P4 (Figs. 21B; 22A–D). Praecoxae, coxae and bases similar to those in L. aff. armata . Exopods 3-segmented; inner margin of second and third segments ornamented with setules; second segment with one plumose (P2) or one long plumose (P3–P4) inner seta; distal segment with one short plumose (P2) or one long plumose inner (P3–P4), two apical setae and three outer spines. Endopods 2-segmented, shorter than exopods; first segment with one short, distally pectinate (P2–P3) (Figs. 21B; 22C) or one long, distally pectinate (P4) (Fig. 22D) seta; second segment with three inner setae (two distally pectinate and one plumose), two apical setae (one naked and one plumose) and one outer spine (P2) or two plumose inner setae, two plumose apical setae and one outer spine (P3) or two inner setae (proximal one distally pectinate), one apical plumose seta and one outer spine (P4).

Fifth pair of legs (Fig. 23B) fused medially, baseoendopod well developed. Endopodal lobe with six elements; setae I–II spiniform, bipinnate; setae V–VI bipinnate. Exopod distinct, ellipsoidal, with five long naked setae.

Sixth pair of legs (Fig. 23A) with one bipinnate seta each.

Caudal rami (Figs. 20D) about 1.75 times as long as broad, with six setae. Position of setae similar to L. aff. armata . Seta IV fused basally to seta V. Size of spinules around ventral distal margin (Fig 23A) smaller than in L. aff. armata .

Description of male. Body (Fig. 24A–B) cylindrical, tapering posteriorly; without microspinular ornamentation except for ventral surface of the anal somite (Fig. 23C). Total body length about 811 μm (mean = 643 μm, n = 5). Maximum width: 184 μm (mean = 174 μm; n = 5). Ventral posterior margin (Fig. 23C) of third and fourth urosomites with continuous row, fifth abdominal somite with paired rows of spinules. Spinules irregular in size, displaying peculiar pattern. Sexual dimorphism in body size and spinular/microspinular ornamentation, antennule, P2–P3 endopod, P5 and P6.

P2 endopod (Fig. 21C). Inner seta on first segment without ornamentation; inner apical seta of distal segment plumose and longer than in female.

P3 endopod (Fig. 22E) 3-segmented. First segment squarish with one distally pectinate inner seta; second segment squarish, with one plumose inner seta and recurved apophysis. Length of apophysis about 2.6 times longer than distal segment. Distal segment longest, rectangular, with two plumose apical setae.

Setal formula of swimming legs as in L. aff. armata .

Fifth pair of legs (Fig. 23C) fused; baseoendopod and exopod forming common plate. Exopodal lobe with six bipinnate setae, endopodal lobe with three bipinnate setae; outer basal seta naked. Comparison of relative length of exopodal setae as follows: III>I>IV>II>VI>V.

Sixth pair of legs (Fig. 23C) asymmetrical; with three setae each, inner seta longest, bipinnate.

Etymology. The new species is named after its type locality.