Phyllopodopsyllus kitazimai, Lee & Yoo & Kim, 2017

Lee, Sue Yeon, Yoo, Jung Sun & Kim, Seung Tae, 2017, Two new Phyllopodopsyllus (Copepoda, Harpacticoida) from Korean marine interstitial, Journal of Species Research 6, pp. 185-214 : 187-201

Phyllopodopsyllus kitazimai sp. nov.

( Figs. 1A, B and 2-10)

Type locality. Korea, East Coast, Gyeongsangbuk-do province, Yeongdeok-si city, Woncheok-ri village , beach, intertidal sand, interstitial water from a Karaman-Chappuis hole, 36°18.309 ʹ N 129°22.648 ʹ E .

Specimens examined. Holotype female ( NIBR IV 0000287257 ) dissected on one slide; allotype male ( NIBR IV 0000287258 ) dissected on one slide; ten paratype females ( NIBR IV 0000287259-0000287268 ) and nine paratype males ( NIBR IV 0000287269- 0000287277 ) dissected on one slide each; five paratype females and five paratype males in toto on one SEM stub ( NIBR IV 0000287278 ); 100 paratype females and 50 paratype males together in one alcohol vial ( NIBR IV 0000287279 ); all collected from the type locality, 6 May 2016, leg. T. Karanovic.

Etymology. The species is named in honour of late Dr T. Kitazima, as a recognition of his contribution to the taxonomy of this genus. The specific name is a noun in the genitive singular.

Description. Female (based on holotype and 15 paratypes). Total body length, measured from tip of rostrum to posterior margin of caudal rami (excluding caudal setae and appendages) from 509 to 536 μm. Colour of preserved specimen yellowish ( Fig. 1A). Nauplius eye not visible. Prosome comprising cephalothorax (Ct) with completely fused first pedigerous somite and 3 free pedigerous somites (Fp1-Fp3); urosome comprising six urosomites (U1-U6), which include fifth pedigerous somite (U1), genital double-somite (fused genital (U2) and first abdominal (U2) somites), two free abdominal somites without appendages (U4 and U5), and anal somite (U6) with caudal rami (Cr) on posterior margin. Habitus ( Figs. 1A, 2A, 3A) cylindrical, slender, without distinct demarcation between prosome and urosome in dorsal view, but with sharp bend in lateral view; prosome/urosome ratio about 0.9 (in dorsal view); greatest width at posterior end of cephalothorax; cephalothorax only 1.15 times as wide as genital double-somite in dorsal view. Body length/width ratio about 5.4. Free pedigerous somites without pronounced lateral or dorsal expansions. Integument of all somites relatively well sclerotized, generally very smooth, covered with numerous shallow cuticular pits; several irregular rows of minute spinules present on each somite except cephalothorax, but majority of surface devoid of spinules. Hyaline fringe of all somites narrow; that of cephalothorax and first free pedigerous somite smooth, those of other somites finely serrated ( Figs. 2, 3). Surface of somites and caudal rami with total maximum of 185 cuticular organs (29 pairs of cuticular pores, 58 pairs of sensilla, one unpaired dorsal sensillum, and ten unpaired dorsal pores).

Rostrum ( Figs. 2B, C, 3B, C) small, weakly demarcated at base from cephalothorax, linguiform, about as wide as long, its anterior tip hardly reaching beyond anterior margin of lateral wings of cephalothoracic shield, with single dorsal pair of sensilla (Ct-1) at about 2/3 of its length.

Cephalothorax ( Figs. 2B, C, 3B, C) smooth, cylindrical in dorsal view, tapering towards anterior end in lateral view, about 1.7 times as long as wide in dorsal view (including rostrum); representing nearly 30 % of total body length. Hyaline fringe of cephalothoracic shield narrow and smooth. Cephalothoracic shield with nine pairs of pores (Ct-II and Ct-IV to Ct-XI), 28 pairs of sensilla (Ct-2 to Ct-13 and Ct-15 to Ct-30), one unpaired dorsal sensillum (Ct-14), and two unpaired dorsal pores (Ct-I and Ct-III); all pores of similar size, about as large as circular base of sensilla; all sensilla of similar size, long, simple, and slender; sensilla pair Ct-2 at base of rostrum; lateral marginal zone includes sensilla Ct-5, Ct-8, Ct-13, Ct-19, and Ct-28 (see Fig. 3B, C); posterior marginal zone includes only sensilla Ct-29 to Ct-30 (see Figs. 2B, 3B).

Pleuron of first free prosomite (second pedigerous somite) ( Figs. 2D, 3D) mostly smooth, with several irregular dorsal rows of minute spinules in anterior half and several minute spinules in anterior lateral corner, with only five pairs of long sensilla (Fp1-1 to Fp1-5), one unpaired dorsal pores (Fp1-I), and one pair of lateral anterior pores (Fp1-II); posterior marginal zone includes sensilla Fp1-1, Fp1-2, Fp1-4, and Fp1-5, while sensilla pair Fp1-3 situated slightly more anteriorly; posterior marginal sensilla pair Fp1-1 probably serially homologous to sensilla Ct-29 on cephalothorax, while serial homology of other sensilla and pores difficult to deter- mine; hyaline fringe narrow and smooth.

Pleuron of second free prosomite (third pedigerous somite) ( Figs. 2D, 3D) very similar in shape and size to that of first free prosomite, except hyaline fringe finely serrated dorsally; also with five pairs of sensilla (Fp2- 1 to Fp2-5) but with different relative position: sensilla pair Fp2-1 probably serially homologous to sensilla Sp1- 2, Fp2-2 to Fp1-3, Fp2-3 to Fp1-4, and Fp2-5 to Fp1-5, while sensilla pair Fp2-4 without homologoues on first free prosomite; single unpaired dorsal pore (Fp2-I) serially homologous to that on first free prosomite (Fp1-I) and one lateral pair (Fp2-III) with serial homologoues on first free prosomite (Fp1-II), while second pair of pores (Fp2-II) without homologoues on first free prosomite.

Pleuron of third free prosomite (fourth pedigerous somite) ( Figs. 2E, 3E) similar in shape to that of second free prosomite but slightly narrower and shorter, with only four pairs of sensilla (Fp3-1 to Fp3-4) and two pairs of cuticular pores (Fp3-I and Fp3-II); sensilla Fp3-1 to Fp3-3 probably serially homologous to their counterparts with same Arabic numerals on pleuron of second free prosomite, but sensilla Fp3-1 and Fp3-2 much clos- er to each other; sensilla pair Fp3-4 serially homologous to sensilla Fp2-5; pores Fp3-I and Fp3-II with serial homologoues on second free prosomite (Fp2-II and Fp2- III respectively); hyaline fringe finely serrated dorsally, smooth laterally.

First urosomite (fifth pedigerous somite) ( Figs. 2E, 3E) slightly longer than pleuron of third free prosomite, with four pairs of sensilla (U1-1 to U1-4) and three pairs of pores (U1-I to U1-III); all sensilla probably serially homologous to their counterparts with same Arabic numerals on pleuron of third free prosomite, although sensilla U1-3 and U1-4 closer to each other; serial homology of pores not obvious, except that single unpaired dorsal pore (U1-I) serially homologous to that on first and second free prosomites (Fp1-I and Fp2-I); hyaline fringe as in third free prosomite finely serrated dorsally and smooth laterally.

Second urosomite ( Figs. 2F, 3F, 6 A-C) fused with third urosomite into genital double-somite, with finely serrated dorsal fringe and lateral internal ridges as only evidence of ancestral segmentation, with four pairs of posterior sensilla (U2-1 to U2-4), one unpaired dorsal pores (U2-I), and two pairs of dorso-lateral anterior pores (U2-II and U2-III); dorsal pore (U2-I) and two dorsal sensilla (U2-1 and U2-2) with serial homologoues on first urosomite with same numbers, but other cuticular organs of uncertain serial homology.

Third urosomite ( Figs. 2F, 3F, 6 A-C) fused with second urosomite, with wide and finely serrated hyaline fringe, but lonest combs on ventro-lateral conrers, one unpaired dorsal pores (U3-I), three pairs of anterior pores (U3-II to U3-IV), and three pairs of posterior sensilla: one dorsal (U3-1), one lateral (U3-2), and one ventral (U3-3); establishing serially homologous sensilla of third and second urosomites not easy, except for dorsal pore.

Genital double-somite about 1.2 times as long as wide (ventral view). Genital complex ( Figs. 6C, 8A) with single large and round copulatory pore in distal part of third urosomite, long and narrow copulatory duct, two small and ovoid seminal receptacles in distal part of second urosomite, and central genital aperture in anterior part of second urosomite; aperture covered by reduced sixth legs.

Fourth urosomite ( Figs. 2G, 3G, 6 A-C) narrower and shorter than genital double-somite, with several ventral rows of long hair-like spinule in place where distal part of fifth legs rests, wide and finely serrated hyaline fringe with long combs ventrally and short dorsally, three pairs of posterior sensilla (U4-1 to U4-3), single central dorsal pore (U4-I), and two pairs of lateral pores (U4-II and U4-III); all sensilla and pores with serial homologoues with same numbers on third urosomite, but ventral pair of spinules (U4-3) closer to each other.

Fifth urosomite (preanal) ( Figs. 2G, 3G, 6 A-C) significantly narrower and slightly shorter than fourth urosomite, without sensilla, with single central dorsal pore (U5-I) and one pair of ventro-lateral pores (U5-II); hyaline fringe wide and finely serrated.

Sixth urosomite (anal) ( Figs. 2H, 3H, 6 A-C) slightly narrower and significantly longer than fifth urosomite, cleft medially in posterior part, with one pair of large dorsal sensilla (U6-1), single central dorsal pore (U6- I), two pairs of lateral pores (U6-II and U6-III), one pair of ventral pores (U6-IV), and posterior row of spinules along ventral margin of medial cleft and along dorso-lateral cuticular wing; anal operculum broad, narrow, and convex, with finely serrated posterior margin, representing about 54% of somite’s width; anal sinus ( Fig. 2H) widely opened, without any chitinous projections, with weakly sclerotized walls and three rows of long, hair-like spinules boarding anus.

Caudal rami ( Figs. 2H, 3H, 6 A-C) strongly sclerotized, conical but with particularly inflated anterior dorsal region, with finely serrated ventral posterior margin, about as long as greatest width, with narrow space between them; ornamented with several short rows of large spinules along inner margin, one outer dorsal transverse row of small spinules, and two small lateral pores (Cr-I and Cr-II); armed with seven setae (three lateral, one dorsal, and three apical). Dorsal seta slender and smooth, about as long as ramus, inserted close to posterior margin, triarticulate at base (i.e., inserted on two pseudojoints). Proximal lateral setae inserted very close to each other at about midlength; ventral one minute, shorter than most sensilla; dorsal one slender and unipinnate, 1.2 times as long as ramus. Distal lateral seta also slender and smooth, inserted at 3/4 of ramus length, and about half as long as ramus. Innermost apical seta smooth, slender, and small, about half as long as ramus. Central (principal) apical seta without breaking plane, very strong, distally pinnate, about 3.5 times as long as caudal ramus, basally fused to outer principal seta. Out- er apical seta also without breaking plane, much more slender than central apical seta, smooth, about 1.3 times as long as caudal ramus.

Antennula ( Figs. 2C, 3C, 5A, 7A) eight-segmented, about as long as cephalothorax, with robust and long aesthetasc on fourth segment fused basally to slightly longer seta, slender and much shorter apical aesthetasc on eighth segment fused basally to two slightly longer setae, and setal formula 1.9.8.3.2.4.4.7. Two lateral setae on seventh segment and four lateral setae on sixth segment biarticulate (i.e., inserted on short pseudojoint); all setae slender and only one seta on second segment and single seta on first segment pinnate. Only ornamentation short arched row of spinules at base of first segment, on dorso-median surface. Length ratio of antennular segments, from proximal end and along caudal margin, 1: 0.5: 0.5: 0.4: 0.2: 0.2: 0.2: 0.4. First segment also strongest, about 2.2 times as long as wide; fourth segment slender, with prominently protruded anterior distal corner at base of large easthetasc.

Antenna ( Figs. 5A, 7B) comprising coxa, allobasis (fused basis and first endopodal segment), two-segment- ed endopod, and much smaller one-segmented exopod. Coxa very short, 0.3 times as long as wide, unarmed, and unornamented. Allobasis cylindrical, 1.8 times as long as wide and nearly seven times as long as coxa, also unarmed, ornamented with longitudinal row of minute spinules along inner margin. First endopodal segment also cylindrical, 2.2 times as long as wide, and about 1.2 times as long as allobasis, unarmed, ornament- ed with longitudinal row of minute spinules along inner margin. Second endopodal segment most robust, more slender proximally but also generally cylindrical, three times as long as wide, 1.2 times as long as first endopodal segment, with two surface frills distally and row of large spinules along inner margin; lateral armature consisting of two strong, smooth spines, flanking slen- der and short seta; apical armature consisting of seven elements: one smooth, slender, short seta, one smooth short spine, one pinnate slender seta, and four geniculate unipinnate setae, longest fused basally to slender pinnate seta; all geniculate setae of similar length, slightly longer than second endopodal segment. Exopod slender, cylindrical but slightly curved, about four times as long as wide and half as long as allobasis; ornamented with posterior row of minute spinules; armed with one lateral and two apical unipinnate setae; outer apical seta strongest and spiniform, fused basally to exopod, about 1.2 times as long as inner apical seta, and 0.8 times as long as lateral seta.

Labrum (not illustrated) large, trapezoidal, rigidly sclerotized, with slightly convex cutting edge, ornament- ed with numerous slender apical and subapical spinules, those on outer distal corners strongest.

Mandibula ( Figs. 5A, 7C, D) composed of large coxa and equally large palp; palp composed of basis, one-segmented endopod and one-segmented exopod; cutting edge of coxa narrow, armed with three large bi- or tricuspidate teeth, one unipinnate dorsal seta, and dorsal row of 6-7 slender spinules. Basis pentagonal, about 0.7 times as long as coxa, 2.4 times as long as wide, unornamented, armed with three apical pinnate setae of similar length and about 0.7 times as long as basis. Endopod cylindrical, 6.4 times as long as wide and 1.2 times as long as basis, unornamented, armed with two lateral and seven apical smooth and slender setae; lateral setae inserted very close to each other, about half length of endopod. Exopod conical, minute but distinct segment, twice as long as wide and only 0.13 times as long as endopod, unornamented, armed with one minute and smooth lateral seta and one pinnate apical seta.

Maxillula ( Fig. 7E) composed of praecoxa, coxa, basis, one-segmented endopod, and one-segmented exopod. Praecoxa large, arthrite highly mobile, armed apically with seven strong spines (ventralmost smooth, others unipinnate) and dorsalmost unipinnate seta, with additional three smooth setae (or large spinules?) on dorsal surface, and additional two slender and smooth seta on anterior surface. Coxa small, unornamented, armed with one outer slender seta and three inner curved and strong setae, all pinnate and of similar length. Basis significantly wider and twice as long as coxa, about 2.6 times as long as wide, unornamented, armed with five unipinnate and three smooth setae along inner margin. Endopod 0.7 times as long as basis and about 2.7 times as long as wide, ornamented with hair-like spinules along outer margin, armed with one inner and three apical bipinnate setae of about same length. Exopod less than half as long as basis and twice as long as wide, ornamented with hair-like spinules along inner margin, armed with three apical bipinnate setae; outermost one about 1.5 times as long as two others and nearly 2.5 times as long as exopod.

Maxilla ( Fig. 7F) composed of syncoxa, basis and two-segmented endopod. Syncoxa large, ovoid, unornamented, with four endites; endites of about same length, proximal two unornamented, distal two with arched row of minute spinules on anterior surface, armed with two, one, three, and three setae respectively from proximal side. Basis much smaller than syncoxa, elongate, with strong apical spine transformed into claw-like structure, ornamented with arched row of minute spinules on anterior surface, armed additionally with one strong apical seta and two smooth setae, one on anterior, and one on posterior surface; anterior seta half as long as posterior one. Endopod minute, with much shorter first segment than second, each armed with one strong geniculate spine and two slender setae; one slender seta on first segment minute.

Maxilliped ( Fig. 7G) prehensile, three-segmented, composed of syncoxa, basis, and one-segmented endopod. Syncoxa twice as long as wide, restricted in central part, ornamented with five short rows of long spinules (two posterior, three on anterior surface), armed with two plumose and one pinnate setae near inner-distal corner. Basis largest segment, nearly 4.3 times as long as wide and 1.3 times as long as syncoxa, cylindrical but wider in central part, ornamented with single longitudinal row of large spinules along inner margin in proximal half, and armed with single smooth inner seta around midlength; seta as long as larges spinules. Endopod smallest segment, 3.6 times as long as wide and 0.3 times as long as basis, cylindrical but narrower distally, unornamented, armed with one apical claw-like spine and one subapical slender seta; apical spine 2.3 times as long as basis and nearly 1.5 times as long as subapical seta.

All swimming legs ( Fig. 8 B-E) slender, short in comparison to body length and width, composed of small unarmed and unornamented triangular praecoxa, large unarmed but ornamented quadrate coxa, smaller armed basis, three-segmented armed and ornamented exopod, and two-segmented armed and ornamented endopod. Coxae in all pairs of legs connected by unornamented intercoxal sclerite, each with concave distal end and no spiniform protrusions.

First swimming leg ( Fig. 8B) with widest intercoxal sclerite (nearly three times as wide as long), biggest praecoxa, smallest coxa, longest basis, and longest endopod of all swimming legs. Coxa slightly longer than wide, narrower in distal part than proximal, with short outer spiniform process, ornamented with two anterior and one posterior row of spinules. Basis slightly longer than wide, with one inner and one outer strong, unipinnate spine, inner one stronger and about 1.7 times as long as outer; ornamentation consisting of row of short spinules at base of each spine on anterior surface, one row of hair-like spinules along inner margin, and single basal pore on anterior surface. Exopod with all segments of about same length, each about 2.5 times as long as wide; first and second segment armed with single strong outer spine each, third segment armed with two out- er spines and two apical geniculate setae; all exopodal segments ornamented with strong spinules along out- er margin and second segment additionally with hair-like spinules along inner margin; inner geniculate seta on third segment slightly longer than entire exopod and about 1.6 times as long as outer geniculate seta. Endopod geniculate and longer than exopod; first endopodal segment nearly 1.4 times as long as entire exopod, more than eight times as long as wide, and 5.6 times as long as second endopodal segment, unarmed, ornamented with hair-like spinules along inner margin; second endopodal segment about twice as long as wide, ornamented with posterior row of small spinules on anterior surface, armed with two apical elements, outer strong spine and inner long and geniculate seta; endopodal apical seta slightly shorter than exopodal outer apical seta but much stronger, and about 1.6 times as long as apical endopodal spine.

Second swimming leg ( Fig. 8C) with nearly square intercoxal sclerite and much shorter praecoxa than in first leg. Coxa without spiniform process on outer margin, ornamented with three rows of spinules on anterior surface, one on posterior surface, but also with small spinules along inner margin, and strong spinules along outer margin. Basis armed only with outer spine, ornamented with only one row of spinules on posterior surface, minute spinules along inner margin (no spinules on anterior surface), and anterior basal pore. Third exopodal segment slightly longer and more slender than other two; distal inner corners of first and second exopodal segments with serrated hyaline frills and distal outer corners transformed into spiniform processes; first exopodal segment armed with inner strong seta and outer strong spine; second exopodal segment armed only with outer spine; third exopodal segment armed with two outer strong spines, strong outer apical seta, and slender inner apical seta; all exopodal segments with spinules along outer and inner margins, and third segment also with cuticular pore on anterior surface; third exopodal segment about 3.6 times as long as wide. Endopod about 0.4 times as long as exopod, both segments ornament- ed with spinules along inner margin only and of similar length but proximal one wider and unarmed; second segment armed with two or three apical elements: outer strong spine, central minute and slender seta (sometimes missing), and outer long and slender seta; apical edopodal spine about as long as endopod and half as long as inner apical seta.

Third swimming leg ( Fig. 8D) very similar to second, except intercoxal sclerite narrower, basis with slender and long outer seta instead of spine, and third exopodal segment nearly six times as long as wide.

Fourth swimming leg ( Fig. 8E) relatively similar to third leg, but with wider coxa, shorter basal seta, much shorter first endopodal segment armed with inner seta, slenderer seta on first exopodal segment, second exopodal segment armed with inner seta, and third exopodal segment with three strong inner setae; central inner seta on third exopodal segment exceptionally long and strong, about 0.8 times as along as entire exopod.

Fifth leg ( Figs. 1A, 5B, C, 8F) typically foliaceous, twice as long as wide, with completely fused baseoendopod and exopod, forming brooding chamber with genital double-somite and anterior part of fourth urosomite normally containing two large eggs, ornamented with row of hair-like spinules between base and basal slender seta and two cuticular pores on anterior surface. Former baseoendopod armed with three slender and pinnte setae, most distal longest. Former exopod armed with six setae; most proximal and fifth seta smooth and slender and inserted on anterior surface, others short, plumose, and inserted on distal margin; distal margin between second and third setae and between third and fourth setae transformed into bicuspidate chitinous process, and between fifth and sixth setae transformed into finely serrated wide hyaline fringe.

Sixth leg ( Fig. 6C) minute cuticular plate, about as long as wide, unornamented, armed with three apical setae; outermost seta strong and plumose, about as long as genital double-somite, 4.8 times as long as innermost slender and smooth seta, and nearly 5.6 times as long as central slender and smooth seta.

Male (based on allotype and 14 paratypes). Body length from 450 to 485 μm. Habitus shape ( Fig. 1B), body proportions, and segmentation as in female, except second and third urosomites not fused ( Fig. 9 A-C). Ornamentation and shape of cephalothorax ( Fig. 4B, C), all free prosomites ( Fig. 4D), and first urosomite ( Fig. 4E), as well as colour and nauplius eye ( Fig. 1B), as in female.

Second urosomite (genital somite) ( Figs. 4E, 5F, 9 AC) about 1.6 times as wide as long in dorsal view, with small spermatophore in right or left half, as in female with three pores (U2-I to U2-III) and four sensilla (U2-1 to U2-4), only one gonopore functional (covered by reduced sixth leg) but it could be left ( Fig. 5F) or right ( Fig. 9C).

Third urosomite ( Figs. 4F, 5F, 9 A-C) as in female with three pairs of sensilla (U3-1 to U3-3) and four pores (U3-I to U3IV), but without hair-like spinules on ventral surface and with hyaline fringe finely serrated (with minute combs) on all sides.

Fourth urosomite ( Figs. 4F, 9 A-C) ornamented as in female with three pairs of sensilla (U4-1 to U4-3) and three pores (U4-I to U4-III), but smaller, cylindrical, and with hyaline fringe uniformly finely serrated (no long combs on ventral side).

Fifth urosomite ( Figs. 4G, 9 A-C) ornamented as in female with two pores (U5-I and U5-II) but slightly slenderer.

Sixth urosomite ( Figs. 4G, 9 A-C) ornamented as in female with one pair of sensilla (U6-1) and four pores (U6-I to U6-IV) but much narrower and with longer spinules on anal operculum.

Caudal rami ( Figs. 4H, 9 A-C) much larger in comparison with anal somite than in female, almost cylindrical but with prominent dorsal ridge and tapering toward posterior end, about 3.2 times as long as wide in ventral view and 1.3 times as long as anal somite; ornamentation and all armature as in female, except no spinules along inner margin.

Antennula ( Figs. 4C, 5D, G, H, 10A), strongly prehensile, robust, with almost all segments shorter than in female, with fused segments four and five, as well as seven and eighth (resulting in apparent six-segmented state); sixth segment and ancestral segments four and five highly transformed into robust pincers with several chitinous ridges along area of contact; additional armature present on second, third, and ancestral fourth somites, while sixth and ancestral fifth segments with reduced armature; position and nature of aesthetascs as in female, except apical one comparatively shorter; setal formula: 1.11.11.11.1.11; several setae on third and ancestral fourth segments very short and several of them spiniform; same six setae on ancestral seventh and eighth segments biarticulated.

Antenna ( Fig. 5D), labrum ( Fig. 5E), mandibula ( Fig. 5E, G), maxillula ( Fig. 5E), maxilla ( Fig. 5E, G), maxilliped ( Fig. 5E, G), exopod and endopod of first swimming leg, exopod of second swimming leg, exopod of third swimming leg, and first two endopodal segments of fourth swimming leg as in female.

Endopod of second swimming leg ( Fig. 10B) also two-segmented as in female but second segment with two spiniform and strong elements (one fused basally to segment) and one short element, all of them smooth.

Endopod of third swimming leg ( Fig. 10C) secondarily three-segmented, with outer spine on second segment, and two other elements on third minute segment; all three elements smooth, and outer spine curved inwards.

Fourth swimming leg ( Fig. 10D, E) with only two inner setae on third exopodal segment and with both elements on second endopodal segment smooth; also outer spine on second endopodal segment curved inwards.

Fifth legs ( Figs. 4E, 5F, 10F) completely different in shape from those in female, two-segmented, composed of large baseoendopod and small exopod but baseoendopods fused medially; as in female outer basal seta long and slender and endopodal lobe with three elements but central element longest; only one cuticular pore present at base of outer basal seta; exopod about twice as long as wide, unornamented, armed with four or five setae; all endopodal elements and two innermost exopodal elements bipinnate, others smooth; length ratio of endopodal armature elements, from inner side, 1: 3: 1.4; length ratio of exopodal armature (with five elements), from inner side, 1: 0.8: 0.4: 0.5: 0.7.

Sixth leg ( Figs. 4E, F, 5F, 9C) short cuticular plate but larger than in female, unornamented, armed with three elements as in female but all smooth and central longest; length ratio of armature, from inner side, 1: 1.2: 0.9.

Variability. Remarkably, there is no variability in the number of sensilla and pores, although the exact position of some cuticular organs could vary between specimens (compare Figs. 4E and 9B for pores U2-II and U2- III). Another common form of obvious variability is the presence/absence of a minute central seta on the second endopodal segment of second to fourth legs in female, and in some specimens this was also a form of asymmetry; while most specimens have this element on at least one leg and at least one side, some have it on all legs and on both sides. One paratype female was observed with a deformed endopod of the right fourth leg, without seta on first segment and only apical spine on second, while the left fourth leg was normal. One paratype male was observed without inner seta on the right first exopodal segment of fourth leg, while the left fourth leg was normal. One paratype male was observed with both apical setae short on the second endopodal segment of right fourth leg, while the left fourth leg was normal. In males the spermatophore could be on the right or left side of genital segment, and accordingly left or right sixth leg could function as a genital operculum (being demarcated at base).