Brevicyclops asetosus

Totakura, Venkateswara Rao & Reddy, Yenumula Ranga, 2015, Groundwater cyclopoid copepods of peninsular India, with description of eight new species, Zootaxa 3945 (1), pp. 1-93 : 50-55

Brevicyclops asetosus n. g., n. sp.

( Figs. 30–33 )

Type locality. River Krishna at Madipadu village (16°48 ′ 50 ′′ N 80°04 ′ 22 ′′ E, elevation 40 m) (water temperature 27ºC, pH 7.0) in Guntur District, Andhra Pradesh, South India ( Fig.1 ).

Type material examined. Holotype female (MNHN-IU-2013-11868), undissected on 1 slide; and 1 paratype female, dissected on 2 slides (MNHN-IU-2013-11869); 12 October 2008; Coll. V. R. Totakura.

Diagnosis. Medium-sized cyclopinae; total body length of females 324–402 µm. Genital double-somite about as long as wide; anal operculum of moderate size, bowl-shaped, with fine serrulate margin, hardly reaching distal margin of anal somite. Caudal rami 1.8 times as long as wide, unornamented; principal outer apical seta completely absent, and dorsal seta 2.3 times as long as ramus. Antennule 11-segmented in female. Legs 1–4 with 2-segmented rami in both sexes; spine formula of second exopodal segment of legs 1–4: 2.2.2.2; setal formula: 5.5.5.4; coxa of all legs unornamented. Inner basal spine of leg 1 absent. Intercoxal plates of legs 1–4 with rounded small prominences, coxal armature present only on legs 2 and 3. Leg 4 endopod 1.3 times as long as wide, armed with 1 spine and 1 seta apically. Leg 5 reduced to 3 setae: basipodal seta plumose, inner 2 setae unequal and smooth. Leg 6 reduced to 2 very small elements.

Description of adult female. Total body length, measured from base of rostrum to posterior margin of caudal rami (excluding caudal setae), 324 Μm. Naupliar eye absent. Body ( Fig. 30 a) somewhat robust, with prosome/ urosome ratio 1.6 and greatest width at posterior end of cephalothorax. Body length/width ratio 2.8. Cephalothorax ( Fig. 30 a) 0.9 times as long as wide, not produced postero-laterally, and 46.2% of total body length. Rostrum ( Fig. 32 a) well developed, broadly triangular, furnished with 2 large sensilla. Free pedigerous somites 2–4 only slightly produced at distal angles, postero-lateral margins rounded; fifth pedigerous somite with oblique lateral margins. Second pedigerous somite about as wide as cephalothorax. Arthrodial membranes between free pedigerous somites moderately developed and hyaline frill slightly developed mid-dorsally, smooth on all somites; all somites partially perforated, no cuticular windows, and sensilla discernible. Pseudosomite between prosome and urosome absent. Medial part of fifth pedigerous somite 0.9 times as wide as genital double-somite and ornamented with 4 sensilla. Genital double-somite ( Fig. 30 a–c) somewhat expanded subproximally, 0.9 times as long as wide and ornamented with 4 sensilla near posterior border; genital apparatus as in Fig. 30 c; hyaline fringe of genital double-somite as well as next 2 somites narrow and smooth. Anal somite ( Fig. 30 a–c) 0.6 times as long as wide, ornamented with transverse row of tiny spinules latero-ventrally on posterior margin and 2 small sensilla dorsally. Anal operculum ( Fig. 30 a, b) moderately developed, bowl-shaped, 71% of somite’s width, not reaching posterior margin of somite, nearly straight, with finely serrulate posterior margin. Anal sinus wide, without apparent ornamentation.

Caudal rami ( Fig. 30 b, c): parallel, close to each other and about 1.3 times as long as anal somite; each ramus 1.8 times as long as sub-proximal maximum width and unornamented disto-ventrally ( Fig. 30 c); dorsal seta inserted at 4/5 of ramus length and biarticulate at base, 0.4 times as long as inner apical seta; lateral seta arising from dorsal surface close to outer margin at 3/5 of ramus length and about half as long as maximum width of ramus; outermost apical seta 0.9 times as long as ramus, inserted subterminally; innermost apical seta slender and about half as long as outermost apical seta; inner principal apical seta without breaking plane; outer seta completely absent; inner seta about 2.2 times as long as dorsal seta; outermost apical seta about twice as long as innermost seta; both these setae unipinnate; all other setae bipinnate.

Antennule ( Fig. 31 a): 11-segmented, ornamented with row of spinules proximally on first segment, with armature formula as follows: 7.1.5.2.1.2.2.2.2.2.7+aes. Segments 1, 3, 6, 7, 9, 10 and 11 with 1, 2, 1, 2, 1, 2 and 4 long bipinnate setae, respectively; all other setae smooth. Length ratios of antennular segments along medial axis 1.0: 0.2: 0.6: 0.3: 0.2: 0.4: 0.6: 0.5: 0.3: 0.5: 0.6.

Antenna ( Fig. 31 b): 4-segmented, consisting of coxobasis and 3-segmented endopod. Setal formula of endopod: 1.5.7. Coxobasis about twice as long as wide, armed with 1 seta at inner distal corner and unornamented; exopodal seta absent. First endopodal segment 1.3 times as long as wide, ornamented with 1 row of spinules at outer distal corner and armed with 1 seta on subdistal inner margin; second endopodal segment 2.2 times as long as maximum width; third endopodal segment 2.6 times as long as wide. Other details same as in type species.

Labrum ( Fig. 32 b): relatively small, trapezoidal, anterior cutting edge almost straight, with 12 moderate-sized, acute teeth between slightly produced triangular lateral lobes; ornamented with 2 groups of hair-like spinules on dorsal surface.

Mandible ( Fig. 32 c) and maxillule ( Fig. 32 d): same as in type species.

Maxilla ( Fig. 32 e): endopodal proximal segment armed with 2 claws; proximal claw with serrulate inner margin and 2.4 times as long as distal one. Other details as in type species.

Maxilliped ( Fig. 32 f): same as in type species.

Legs 1–4 ( Fig. 33 a–d): short, with 2-segmented exopod and endopod. Hairs present on rounded inner margin of basis and lateral margins of exopod and endopod, as illustrated. Endopod nearly as long as exopod on legs 1–3, but distinctly shorter on leg 4. Second exopodal segment spine formula: 2.2.2.2; setal formula: 5.5.5.4. Coxae of all legs unornamented. Intercoxal plates with 2 small rounded unornamented prominences each on all legs. Inner basal spine absent on leg 1. Coxal seta present on legs 2 and 3 only. Spine and setal formulae (legend: same as that of Paracyclopina orientalis ):

Coxa Basis Exopod Endopod

1 2 1 2

Leg 1 0-0 0-1 0- I 4, 1+I, I 1 -0 1, 1+I, 1 Leg 2 1-0 0-1 0- I 4, 1+I, I 1 -0 1, 1+I, 1 Leg 3 1-0 0-1 0- I 4, 1+I, I 1 -0 1, 1+I, 1 Leg 4 0-0 0-1 0- I 3, 1+I, I 1 -0 1+I Leg 5 ( Fig. 30 a–c): completely fused to somite and represented by 3 plumose setae; basal seta longest and lying on small protuberance; other 2 setae simple, unequal and located on short prominence, representing ancestral distal segment.

Leg 6 ( Fig. 30 a–c): trapezoidal, plate-like and armed with 2 reduced spiniform setae.

Male unknown.

Etymology. The specific epithet is derived from the Latin adjective setosus (= bristle-bearing) to which the Latin a - (= without) is prefixed, alluding to the absence of the principal outer apical caudal seta; gender masculine.

Distribution and ecology. The new species was collected only from the type locality where it was accompanied by Habrobathynella sp., Anzcyclops indicus n. sp., Parastenocaris curvispinus Enckell.

Figures

FIGURE 1. Map showing the type localities of the cyclopoid species on the Indian peninsula.

FIGURE 30. Brevicyclops asetosus n. g., n. sp., holotype female. (a) habitus, dorsal; (b) urosome, dorsal; (c) same, ventral (arrow pointing to lack of outer medial apical seta).

FIGURE 31. Brevicyclops asetosus n. g., n. sp., holotype female. (a) antennule, lateral; (b) antenna, lateral.

FIGURE 32. Brevicyclops asetosus n. g., n. sp., holotype female. (a) rostrum, ventral; (b) labrum, ventral; (c) mandible, lateral; (d) maxillule, lateral; (e) maxilla, lateral; (f) maxilliped, lateral.

FIGURE 33. Brevicyclops asetosus n. g., n. sp., holotype female. (a) leg 1, anterior; (b) leg 2, anterior; (c) leg 3, anterior; (d) leg 4, anterior.