Chaulionyx paivacarvalhoi, Kihara & Huys, 2009

Kihara, Terue & Huys, Rony, 2009, A new genus of Ectinosomatidae (Copepoda, Harpacticoida) from sublittoral sediments in Ubatuba, São Paulo State, Brazil, including an updated key to genera and notes on Noodtiella Wells, 1965, ZooKeys 17 (17), pp. 57-88 : 62-74

Chaulionyx paivacarvalhoi sp. n.

urn:lsid:zoobank.org:act:0075F457-E809-451D-9CFB-9B2B1BE2EF19

Figs 1-37

Type locality. Brazil, northern coast of São Paulo State, Ubatuba (23 ° 41.4’ S, 44 ° 58.8’ W), 44 m depth (station 17 V in Table 1 ).

Material examined. Holotype female in ethanol (reg. no. MZUSP 16467 ). Undissected paratypes (in ethanol) deposited in MZUSP (reg. nos 16468, 19063-19065) are 1 female and 1 male from station 17 V; 3 females and 1 male from station 16 V, 2 males from station 16I, 1 female and 1 male from station 17I. Additional undissected paratypes (in ethanol) deposited in NHM are 2 males from station 17 V (reg. nos 2009.1-2), 3 females from station 27 V (reg. nos 2009.3-5) and 1 male from station 27I (reg. no 2009.6). Dissected paratypes and other material examined are retained in the personal collection of C.E.F. da Rocha (Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo). All material collected by T. Corbisier.

Description. FEMALE ( Figs 1-21 , 27-35 ). Body length 260-290 µm (n = 4; mean = 275 µm). Body ( Fig. 1 ) fusiform, maximum width measured at posterior margin of cephalic shield; body somites gradually tapering posteriorly. Cephalic shield with minute integumental pits and numerous pores; paired chitinous patches present dorsally in posterior half (for examples of these integumental structures see labelling in Fig. 1 and accompanying legend). Body somites with thickly chitinized cuticle; pedigerous somites and second abdominal somite with large middorsal pore; genital double-somite with 2 pores. Sensillae long and fine, distributed as illustrated in Fig. 1 . Hyaline frill of cephalic shield and somites bearing P2–P4 plain, partially concealing fine spinular rows located in anterior half of succeeding somite ( Fig. 1 ); frills of urosomites minutely denticulate ( Figs 1-2 , 30-31 ).

Genital and first abdominal somites fused forming double-somite ( Figs 1-3 , 21 ); slightly longer than broad; posterior margin with continuous spinular row; original segmentation marked by sensilla, paired dorsal chitinous patches and a middorsal pore ( Fig. 2 ). Second and third abdominal somites with a continuous row of coarse spinules around ventral posterior margin ( Fig. 3 ). Penultimate somite with a small pseudoper-

culum ( Figs 1-2 , 30 ), dorsal surface and distal margin with rows of spinules ( Figs 30, 32 ). Anal somite ( Figs 1 -4 , 30 ) medially cleft; dorsal surface with paired anterior rows of minute spinules and pairs of sensilla and pores ( Fig. 4 ); distal margin with small spinules ( Fig. 33 ); anal operculum absent.

Caudal rami ( Figs 4-6 ) about as long as wide, with 7 naked setae; bases of terminal setae covered by rounded membranous serrate extension dorsally ( Figs 4 , 30, 34 ) and an acuminate lappet ventrally ( Fig. 5 ). Seta I minute, with bifid apex. Setae IV–V fused basally, without fracture planes. Seta V longest and swollen in proximal half. Seta VII tri-articulate at base.

Rostrum large ( Figs 7 , 27 ), ventrally deflected; broadly rounded, quadrangular; not defined at base but original demarcation marked by membranous areas bilaterally ( Fig. 27 ); no sensilla discernible.

Antennule ( Fig. 8 ) short, 5-segmented. Segment 1 with pinnate seta; segment 3 with conspicuous aesthetasc; distal segment long, with apical acrothek consisting of aesthetasc and 2 slender setae. Armature formula: 1-[1 pinnate], 2-[7], 3-[6 + (1 + ae), 4-[1], 5-[5 + acrothek].

Antenna ( Fig. 9 ) consisting of coxa, basis, 2-segmented endopod and 3-segmented exopod. Coxa small, indistinctly demarcated at base, without ornamentation. Basis unarmed; with some fine spinules along abexopodal margin and coarse spinules set near outer distal corner. Proximal endopod segment with a few coarse spinules near outer distal corner. Distal endopod segment with 2 unipinnate setae laterally; distal margin with spinule row and 5 elements, 2 of which are geniculate, others bipinnate. Exopod with small proximal and middle segments and elongate apical segment; exp-1 unarmed, exp-2 with short naked seta, exp-3 with 2 pinnate apical setae.

Labrum ( Figs 10 , 28 ) well developed, with frontal curved spinous projection bearing large anterior pore.

Mandible with small coxa ( Fig. 11 ) and biramous palp ( Fig. 12 ). Gnathobase reduced, with chitinized dorsal tooth and number of hyaline pointed projections. Basis elongate, with 3 lateral setae. Exopod small, 1-segmented, with 3 naked setae, outer one reduced. Endopod 1-segmented, with row of fine spinules along outer margin; armature consisting of 1 sparsely pinnate and 2 naked setae laterally and 1 bipinnate and 6 naked setae apically.

Maxillule ( Fig.13 ) with fused praecoxa and coxa. Praecoxa with well developed arthrite bearing 4 spines and 1 seta around distal margin and 2 small setae on anterior surface; distalmost marginal spine with long spinules. Coxa represented by small seta on anterior surface near articulation with palp. Endopod incorporated into basis forming elongate segment; proximal basal endite a small protuberance bearing 3 setae; elements of distal basal endite (4) and endopod (3) forming group of 7 setae arranged around the distal margin; with cuticular reinforcement (indicated by asterisk in Fig. 13 ) on posterior surface; distal medial margin with characteristic spinules. Exopod a free small segment; with 1 apical and 1 backwardly directed plumose seta.

Maxilla ( Fig. 14 ) prehensile, comprising syncoxa, allobasis and 2-segmented endopod with syncoxa and allobasis directed at a right angle. Syncoxa with 3 endites; proxi-

mal endite small, with 1 bipinnate and 3 naked setae; middle endite rudimentary, with 1 long naked seta; distal endite cylindrical and recurved, located in membranous area at syncoxa-allobasis joint, with 3 long naked setae. Allobasis robust, expanding in distal half; armed with 3 setae (2 small) near inner distal corner (derived from basis) and 1 strong pinnate seta on posterior surface (derived from incorporated endopod segment). Endopod with 1 geniculate pinnate claw and 1 naked seta on enp-1; enp-2 (representing fused middle and distal segments) with 1 geniculate pinnate claw and 4 naked setae.

Maxilliped ( Fig. 15 ) stenopodial and slender, comprising syncoxa, basis and 1-segmented endopod. Syncoxa with long pinnate seta and few spinules near distal corner. Basis unarmed; with long setules along outer margin and fine spinules along inner margin. Endopod with 1 short pinnate seta laterally and 1 short plus 2 longer (1 plumose) setae apically.

P1 ( Fig. 16 ). Coxa with row of minute spinules along distal margin. Basis with rows of spinules on anterior surface and near insertion of exopod as illustrated; outer seta long, bipinnate and spiniform; inner spine unipinnate with spinules along outer margin. Exopod 3-segmented; with rows of spinules along outer margins; outer spines strong and bipinnate; exp-1 without inner seta; exp-2 with 1 inner plumose seta; exp-3 with 1 inner plumose seta, 2 plumose distal setae and 2 bipinnate outer spines. Endopod 2-segmented, prehensile; enp-1 elongate, with rows of spinules on anterior surface and along outer and distal margins, and 1 plumose inner seta inserted in distal third of segment; enp-2 with 3 plumose inner setae (middle one with bifid apex), 2 plumose distal setae, and 1 curved strong spine with bifid tip ( Fig. 29 ).

P2–P4 ( Figs 17-19 ). Coxa with small spinules along distal margin. Basis with rows of spinules at base of exopod and around outer seta; outer seta plumose (P2) or naked (P3–P4). Exopod 3-segmented; with rows of spinules along outer margins; outer spines strong and bipinnate. Exp-1 with 1 reduced plumose inner seta; exp-2 with 1 plumose inner seta; exp-3 with 2 bipinnate outer spines, 2 plumose distal setae and 2 (P2–P3) or 3 (P4) plumose inner setae. P2 exp-3 outer distal seta plumose along outer margin and with apical flagellum (arrowed in Fig. 17 ). P4 exp-3 proximal inner seta with bifid apex; middle inner seta extremely well developed. Endopod 3-segmented; with rows of spinules along outer margins. Enp-1 with 1 plumose inner seta; enp-2 with 1 reduced plumose inner seta; enp-3 with 4 plumose setae (2 inner and 2 distal) and 1 bipinnate outer spine (P2–P3) or 1 plumose outer seta (P4). Armature formula of swimming legs as for genus.

P5 ( Figs 20 , 35 ). Baseoendopod outer expansion with 1 naked seta. Endopodal lobe with spinular row and small pore on anterior surface; with 2 naked setae, inner one very long (3.2 times longer than outer one) and with bifid apex, outer one with serrate apex. Exopod with 1 pore near distal inner margin and various spinule rows as figured; anterior surface with 1 naked seta; with 3 marginal setae, innermost one with bifid apex.

Genital field ( Figs 3 , 21 ) with relatively small midventral copulatory pore. Sixth pair of legs ( Fig. 21 ) vestigial, fused medially forming a common plate that covers paired genital apertures (or median slit); each P6 with 1 plumose seta. Egg-sac single.

MALE. ( Figs 22-26 , 36-37 ). Body length 230-260 µm (n = 6; mean = 246 µm) ( Fig. 22 ). Sexual dimorphism expressed in caudal ramus, antennule, P1, P5, P6, and in genital segmentation. Ornamentation of body ( Figs 22-23 , 36 ) generally as in female, except for small differences such as cephalic sensilla being longer and distributed differently, and pits, pores and chitin patches missing on the cephalic shield.

Caudal ramus ( Fig. 23 ) with both dorsal and ventral posterior margin produced into triangular extension covering bases of setae IV–VI.

Antennule ( Fig. 24 ), haplocer, 7-segmented; geniculation between segments 5 and 6; segment 5 elongated and incompletely divided. Setae and aesthetasc formula: 1-[1], 2-[7], 3-[3], 4-[1], 5-[7 + ae], 6-[0], 7-[1 + ae].

P1 ( Figs 25 , 37 ). Enp-2 wider than in female; outer distal spine with bifid apex.

P5 ( Figs 23 , 26 ) shorter than in female. Endopodal lobe small, with 2 short, stout setae, innermost with bifid apex, outer one with tridentate apex. Exopod short; with 1 seta on anterior surface and 3 marginal setae; inner distal seta with tridentate apex, outer distal seta very long.

P6 ( Fig. 23 ) asymmetrical, without ornamentation.

Etymology. The new species is named in honour of Prof. João de Paiva Carvalho (Instituto Oceanográfico, Universidade de São Paulo) in recognition of his significant contributions to the taxonomy of Copepoda.

Figures

Figures 1-2. Chaulionyx paivacarvalhoi sp. n. ♀: 1 habitus, dorsal [* = integumental pit; ■ = pore; ● = chitinous patch 2 urosome, dorsal. Scale bars = 10 µm.

Figures 3-6. Chaulionyx paivacarvalhoi gen. et sp. n. ♀: 3 urosome, ventral [segment bearing P5 omitted] 4 caudal rami, dorsal 5 left caudal ramus, ventral 6 left caudal ramus, lateral. Scale bars = 10 µm.

Figures 7-10. Chaulionyx paivacarvalhoi gen. et sp. n. ♀: 7 rostrum (arrowed) and left antennule (armature omitted), dorsal 8 right antennule, dorsal 9 antenna 10 labrum. Scale bars = 10 µm.

Figures 11-15. Chaulionyx paivacarvalhoi gen. et sp.n. ♀: 11 mandibular gnathobase 12 mandibular palp 13 maxillule [asterisk indicating cuticular reinforcement] 14 maxilla 15 maxilliped. Scale bars = 10 µm.

Figures 16-18. Chaulionyx paivacarvalhoi gen. et sp. n. ♀: 16 P1, anterior; 17 P2, anterior [seta with apical flagellum arrowed] 18 P3, anterior. Scale bars = 10 µm.

Figures 19-21. Chaulionyx paivacarvalhoi gen. et sp. n. ♀: 19 P4, anterior [seta with bifid apex arrowed] 20 P5, anterior 21 genital double-somite. Scale bars = 10 µm.

Figures 22-23. Chaulionyx paivacarvalhoi gen. et sp. n. ♁: 22 habitus, dorsal 23 urosome, ventral. Scale bars = 10 µm.

Figures 24-26. Chaulionyx paivacarvalhoi gen. et sp. n. ♁: 24 antennule, dorsal 25 P1 basis and endopod, anterior 26 P5, anterior. Scale bars = 10 µm.

Figures 27-37. Chaulionyx paivacarvalhoi gen. et sp. n. Scanning electron micrographs (♀: 27-35; ♁: 36-37): 27 rostrum, dorsal 28 labrum, anterior 29 bifid outer spine on P1 enp-2 30 second abdominal somite (posterior margin), third abdominal somite, anal somite and caudal rami, dorsolateral 31 detail of serrate posterior margin of second abdominal somite 32 detail of posterior margin of third abdominal somite 33 posterior margin of anal somite 34 posterior margin of caudal ramus showing dorsal semicircular serrate extension 35 P5, anterior 36 prosomal ornamentation, dorsal 37 P1 endopod, anterior. Scale bars: 1 µm (34), 2.5 µm (33), 5 µm (28-29, 31-32, 35), 10 µm 27 (30, 37), 20 µm (36).