Halicyclops martinezi, Totakura, Venkateswara Rao & Reddy, Yenumula Ranga, 2015

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 : 19-30

Halicyclops martinezi n. sp.

( Figs. 9–16 )

Type locality. River Godavari (water temperature 25ºC, pH 7.0) at Kotipalli village (16°41′36.4″N, 82°03′09.9″E; elevation 10 m) in East Godavari District, Andhra Pradesh, South India ( Fig. 1 ).

Type material examined. Holotype female (MNHN-IU-2013-11851) and allotype male (MNHN-IU-2013- 11852), dissected on 3 slides each; 65 paratypes: 1 female (MNHN-IU-2013-11853) and 1 male (MNHN-IU-2013- 11854), dissected on 3 slides each; 2 females (MNHN-IU-2013-11855–11856) and 1 male (MNHN-IU- 201311857) whole-mounted on 1 slide each; 41 females and 9 males in alcohol (MNHN-IU-2013-11858); and 5 females and 5 males in senior author’s personal collection; 24 January 2010; Coll. V. R. Totakura.

Other material examined: River Godavari : South India, Andhra Pradesh, East Godavari District at Kotipalli village (water temperature 23ºC, pH 7.5), 0 2 February 2008: 2 males and 8 females; at Kota village (16°41′36.2″N, 82°03′99.9″E; elevation 10 m; water temperature 28ºC, pH 7.0), 14 January 2010: 1 female only; at Brahmapuri village (16°43′22.1″N, 82°08′18.0″E; elevation 8 m; water temperature 28ºC, pH 7.0), 24 January 2010: 1 male, 4 females; Coll. V. R. Totakura.

Diagnosis. Total body length of female 382–418 Μm; of male 361–435 Μm; cephalothorax subquadrate, without dorsal integumental window, about as long as its greatest width distally and 37.1% of total body length; hyaline fringes on all segments denticulate; pseudosomite present between prosome and urosome; genital doublesomite as long as wide, without lateral projections; ornamented with latero-ventral window on either side of distal half; pseudo-operculum on preanal somite extending up to midlength of anal somite; female antennule 6- segmented, fourth segment 1.9 times as long wide; antenna 4-segmented, second endopodal segment 5.8 times as long wide, with 5 setae on inner margin; mandibular palp represented by 2 reduced, unequal simple setae; maxillulary basis with basally swollen inner medial plumose seta, exopodal seta half as long as endopod seta; maxilla 4-segmented; maxilliped 2-segmented; legs 1–4 spine formula: 3.4.4.3, and setal formula: 5.5.5.4; leg 4 third endopodal segment with spiniform inner setae; caudal rami slightly divergent, each ramus about twice as long as maximum width; ornamentation on principal outer apical seta and principal inner apical seta heteronomous; lateral seta arising from 3/5 of ramus length and 1.3 times as long as maximum width of ramus; outermost apical seta 2.1 times as long as ramus; innermost apical seta 1.8 times as long as outermost apical seta; principal inner apical seta 6.8 times as long as caudal ramus. Leg 5 basis and endopod completely fused to somite; outer basal plumose seta inserted on basal protuberance; exopod armed with 3 strong spines and 1 apical plumose seta. Leg 6 with 2 spiniform setae and 1 small and slender seta. Genital field located anteriorly.

Description of adult female. Total body length, measured from base of rostrum to posterior margin of caudal rami (excluding caudal setae), 486 Μm. Preserved specimens colourless. Naupliar eye absent. Body ( Fig. 9 a) robust, perforated, cyclopiform, with prosome/urosome ratio 1.3 and greatest width at posterior end of cephalothorax (159 Μm). Body length/width ratio 2.7. Cephalothorax ( Fig. 9 a) about as long as its greatest width at distal end, 37.1% of total body length, 2.4 times as wide as genital double-somite, and not produced posterolaterally; hyaline fringe well developed dorsally; ornamented with several small sensilla as illustrated, and without suture on dorsal surface. Rostral projection ( Figs. 9 a, 10a) moderately developed, broadly triangular in dorsal view, with 2 small sensilla on dorsal surface. Second and third free pedigerous somites pointed postero-laterally, ornamented with 4 and 6 sensilla, respectively. Fourth pediger with rounded corners. Pseudosomite present between prosome and urosome. Fifth pedigerous somite about as wide as genital double-somite. Free pedigers 2–3 with well developed denticulate hyaline fringe on distal margin dorso-ventrally.

Urosome ( Figs. 9 a, b, 10b): fifth pedigerous somite with hyaline fringe dorso-ventrally and ornamented with 4 sensilla. Genital double-somite elliptical, 0.9 times as long as wide; hyaline fringe with denticulate margin both dorsally and ventrally; ornamented with 1 vague trapezoidal integumental window in proximal dorsal half, 1 large lateral, cuticular window on either side, 2 large cuticular recesses on each side at midlength, 7 dorsal and 4 ventral pores ( Fig. 10 d) and 6 sensilla dorso-posteriorly ( Fig. 10 c). Copulatory pore ( Fig. 10 d) small; copulatory duct narrow, short and sclerotized. Seminal receptacle very small, ovoid. Ovipores situated dorso-laterally, covered with reduced sixth legs. Sixth legs ( Fig. 10 c, e) bearing 3 short, spiniform elements, innermost one somewhat slender. Preanal somite with denticulate hyaline fringe both dorsally and ventrally, but 2 medial dorsal denticles (pseudooperculum) protruding and extending up to distal-third of anal somite ( Fig. 9 b). Anal somite ( Figs. 9 a, 10b) ornamented with 2 small sensilla on dorsal surface, and transverse row of spinules on posterior margin. Anal operculum smooth and moderately developed, representing 50.8% of anal somite’s width. Anal sinus widely open; ornamented with 2 diagonal rows of fine spinules.

Caudal rami ( Figs. 9 a, 10b): slightly divergent, with basal space between them about 0.7 times as wide as ramus’ width; ramus 1.9 times as long as maximum width, ornamented with spinular row on distal margin ventrolaterally at base of outermost apical seta and at inner distal corner; dorsal seta about 0.6 times as long as principal outer apical seta, inserted at distal fifth of ramus length and uniarticulate at base; lateral seta arising from dorsal surface close to outer margin at 3/5 of ramus length and 1.3 times as long as maximum width of ramus; outermost apical seta 1.2 times as long as ramus, inserted subapically; principal apical setae with breaking planes; inner seta 1.7 times as long as outer seta, 1.2 times as long as urosome, and 6.5 times as long as caudal ramus. All caudal setae plumose.

Antennule ( Fig. 11 a): 6-segmented, extending up to 4/5 of cephalothorax and ornamented with 1 crescentic row of spinules proximally on first segment. Setal formula: 8.12.3+aes.6+aes.2.9+aes. Length ratios of antennular segments along medial axis 1.0: 0.8: 0.4: 1.2: 0.6: 1.0. Segments 1–6 with 3, 3, 3, 4, 2, and 4 long pinnate setae, respectively; all other setae smooth. Probable segmental homology 1 (I–V), 2 (VI–XI), 3 (XII–XIV), 4 (XV–XX), 5 (XXI–XXIV), 6 (XV–XVIII).

Antenna ( Fig. 11 b): 4-segmented, comprising coxa, basis and 2-segmented endopod. Coxa small and unarmed. Basis about as long as first endopodal segment, ornamented with short U-shaped row of tiny spinules near proximal outer corner; armed with 1 smooth seta and 1 pinnate seta at inner distal corner; exopodal seta absent. First endopodal segment 1.9 times as long as wide, armed with 1 smooth seta. Second endopodal segment 5.2 times as long as wide, about twice as long as first one, armed with 5 lateral and 7 apical setae, ornamented with 1 oblique row of spinules on proximal surface and 2 longitudinal rows of small spinules on outer margin.

Labrum ( Fig. 12 a): trapezoidal; anterior edge straight, narrow with 11 small teeth between large lateral teeth; ornamentation not discernible.

Mandible ( Fig. 12 b): coxal gnathobase roughly divided into 3 groups of teeth; inner group of only 2 large unequal teeth, innermost one being larger; middle group of 3 small, more or less equal small teeth and 3 strong spinules between small teeth; outer group comprising 1 simple slender tooth and 1 pinnate outermost seta. Palp represented by 2 small, unequal setae.

Maxillule ( Fig. 12 c): composed of well developed praecoxa and 2-segmented palp. Arthrite of praecoxa bearing 4 very strong spinous processes and 7 armature elements along inner margin (second proximal one longest and pinnate). Palp composed of coxobasis and endopod. Coxobasis 1.8 times as long as wide, with smooth proximal exopodal seta and 2 apical setae (inner one basally dilated, pinnate) and 1 subapical smooth seta; endopod small and distinct at base, with 3 smooth setae (2 apical setae, 1 inner subapical seta).

Maxilla ( Fig. 12 d): 3-segmented, praecoxa partially fused with coxa. Proximal endite of praecoxa small, armed with 2 unequal plumose setae; distal endite small, unarmed. Proximal endite of coxa with 1 short pinnate seta; distal endite highly mobile, bearing 1 completely fused and very stout pinnate seta and 1 small pinnate seta. Basis drawn out into spinulose robust claw and armed with 2 unequal setae; strong seta about as long as claw. Endopod armed with 2 spinulose claws and 3 smooth setae. All strong setae as well as basal claw prehensile.

Maxilliped ( Fig. 12 e): 2-segmented, composed of protopod and 1-segmented endopod. Protopod 3.2 times as long as wide and armed with 2 strong spiniform setae and 1 smooth normal seta; unornamented. Endopod half as long as protopod, armed with 2 strong bipinnate setae and 2 smooth setae and 1 bipinnate strong, claw-like apical seta; apical seta longest, 1.7 times as long as segment and fused at base; unornamented.

Legs 1–4 ( Fig. 13 a–d): with 3-segmented exopod and endopod. Praecoxae of all legs short, unornamented. Coxa ornamented with 1 row of spinules at outer distal margin. Basis slightly larger than coxa, ornamented with 1 row of spinules on distal margin between exopod and endopod and another row at inner distal corner. Inner coxal spine and outer basipodal seta present on all legs; leg 1 basis alone with moderately strong inner spine. Endopod nearly as long as exopod on legs 1–4. Third exopodal segment spine formula: 3.4.4.3, and setal formula: 5.5.5.4. Intercoxal plate with 2 small, rounded prominences ornamented with 3 rows of fine spinules. Spine and setal formulae (legend: same as that of Paracyclopina orientalis ):

Coxa Basis Exopod Endopod

1 2 3 1 2 3

Leg 1 1-0 I-1 1-I 1-I 4, 1+I, II 1 -0 1-0 2, 1+I, I Leg 2 1-0 0-1 1-I 1-I 4, 1+I, III 1 -0 1-0 2, 1+I, II Leg 3 1-0 0-1 1-I 1-I 4, 1+I, III 1 -0 1-0 2, 1+I, II Leg 4 1-0 0-1 1-I 1-I 3, 1+I, II 1 -0 1-0 II, II, I Leg 5 ( Figs. 9 a, b, 10b, c): basis and endopod completely fused to somite; outer basal plumose seta inserted on basal protuberance, which is 1.2 times as long as wide. Exopod about 1.3 times as long as wide; ornamented with 1 row of small spinules along outer margin; armature consisting of 3 strong spines and 1 apical plumose seta; inner spine 0.4 times as long as segment, slightly longer than outer apical spine and proximal outer spine; apical seta 1.5 times as long as segment and about as long as basal seta.

Leg 6 ( Figs. 9 a, 10e): trapezoidal plate, armed with 2 almost equal, smooth dentate spines and 1 smooth and slender spiniform seta, which is slightly longer than spines.

Description of adult male. Total body length, excluding caudal setae, 392 Μm. Habitus ( Fig. 14 a) somewhat slenderer than female. Prosome/urosome ratio 1.7, greatest width (139 Μm) at posterior end of cephalothorax. Body length/width ratio 2.6. Cephalothorax 37% of total body length; anterior one-fifth narrow; postero-lateral corners not produced. Hyaline fringes of all somites well developed with denticulate margin. Fifth pedigerous somite with oblique outer margin. Genital somite ( Figs. 14 a, b, 15a, b) 1.3 times as wide as long in dorsal view. Third urosomite ornamented with 1 pore mid-ventrally ( Fig. 15 b) and 1 large latero-ventral integumental window on either side ( Figs. 14 b, 15b); fourth urosomite ornamented with 2 latero-ventral pores ( Fig. 15 b). Preanal somite, anal somite, and anal operculum similar to female. Caudal rami ( Figs. 14 a, b, 15a, b) almost similar to female, 1.4 times as long as anal somite; each ramus 1.7 times as long as maximum width; armature and ornamentation almost as in female.

Antennule ( Fig. 16 ): 12-segmented, digeniculate, geniculation between segments 5 and 6 and 11 and 12. First segment with 1 short row of spinules at base. Setal formula: 11+2aes.2.5+aes.0.0.1aes.1.2+aes.1+aes.2+aes.1.10+ 3aes., all aesthetascs smooth and simple; segments 8–11 each with 1 small, modified unipinnate seta; segments 1, 2, 3, 12 with 4, 2, 1 and 6 long bipinnate setae respectively; all other setae smooth. Length ratios of antennular segments along medial axis 1.0: 0.2: 0.3: 0.2: 0.3: 0.3: 0.4: 0.2: 0.3: 0.3: 0.7: 1.3.

Labrum ( Fig. 15 c): anterior edge with about 20 small and equal teeth between triangular lateral projections; ornamented with 6 elongate hair-like spinules on dorsal surface and transverse row of 6 large spinules on ventral surface. Other cephalic appendages and legs 1–5 as in female.

Leg 6 ( Figs. 14 b, 15b): distinct, large plate, armed with 3 unequal armature elements.

Etymology. The new species is named in honour of Dr. P. Martínez Arbizu for his significant contributions to the systematics of copepods; the specific epithet is a noun in the genitive singular. Gender masculine.

Remarks. The genus Halicyclops Norman, 1903 is highly speciose and cosmopolitan in distribution. The World Copepoda database on the genus Halicyclops ( Boxshall 2011) contains a list of 76 species and 13 subspecies, which are apparently valid (‘direct child species’). Karanovic (2006) divided the genus into two subgenera: Rochacyclops Karanovic, 2006, and Halicyclops s. str. Now, the former includes two species from Australia, and one each from Belize, Mexico, and Malaysia, whereas all other taxa belong to Halicyclops s. str. In India, only six species are so far known, and all of them belong to Halicyclops s. str. The Indian species and their distribution records are as follows: Halicyclops (Halicyclops) tenuispina Sewell, 1924 , from Lake Chilka, Odisha State; Halicyclops (Halicyclops) spinifer Kiefer, 1935 , from Lake Kolleru, Andhra Pradesh state; Halicyclops (Halicyclops) canui Lindberg, 1941 , from a swamp at Bandra, West Mumbai (erstwhile Bombay); Halicyclops (Halicyclops) electus Lindberg, 1943 , from Mahim, Mumbai; Halicyclops (Halicyclops) konkanensis Lindberg, 1949 , from Konkan, west coast; Halicyclops (Halicyclops) pilifer Lindberg, 1949 from Thane, west coast near Mumbai; and Halicyclops (Halicyclops) martinezi n. sp. from the River Godavari , Andhra Pradesh.

Halicyclops (Halicyclops) has eight groups (Group A–H) based on the spine formula of the third exopodal segment of legs 1–4 (see Pesce 2013). In India, as of now, groups A, B and F exist, and they are characterised by the spine formula 4.4.4.3, 3.4.4.3, and 2.3.3.3, respectively. The position of the lone species of group A, i.e. H. (H.) tenuispina is doubtful because, Sewell (1924: 797, Pl. 47, Fig. 3 ) reported its spine formula as 4.4.4.3, but the figure of leg 4 exopod has four outer spines.

Halicyclops (H.) martinezi n. sp. belongs to the species Group B by possessing, inter alia, the following combination of characters: the spine and setal formulae of the third exopodal segment of legs 1–4 are 3.4.4.3 and 5.5.5.4, respectively; the female genital double-somite is devoid of any protuberance on either side; all the five armature elements of the third endopodal segment of leg 4 are transformed into spiniform structures; the hyaline fringes on all somites denticulate; pseudo-operculum (hyaline fringe of penultimate segment) extending up to 2/3 of anal somite and bifurcate distally; leg 5 has three spines and one seta in both sexes; its exopod is 1.3 times as long as wide, and ornamented with one row of small spinules along outer margin; the inner apical spine is about half as long as its segment, slightly longer than the outer apical spine and about as long as the proximal outer spine; the apical seta 1.5 times as long as segment and about as long as the basal seta; the caudal ramus 1.9 times as long as maximum width and has no tube near the cuticular protuberance of the dorsal seta. The Group B is a rather complex group, comprising most of the known species and subspecies of Halicyclops , which are distributed almost throughout the world ( Pesce 2013).

H. (H.) martinezi n. sp. stands out in the Group B by the inner spine of leg 5 in both sexes being slightly longer than other elements except seta, and the fourth antennular segment in the female about twice as long as wide. It can be easily distinguished from all the Indian congeners by the protruding pseudo-operculum on the preanal somite and the presence of a single seta on the second endopodal segment of legs 1–4.

Figures

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

FIGURE 3. Paracyclopina orientalis (Lindberg, 1941), female, urosome. (a) dorsal; (b) ventral (another specimen).

FIGURE 9. Halicyclops martinezi n. sp., (a) paratype female, habitus, dorsal; (b) holotype female, urosome, lateral.

FIGURE 10. Halicyclops martinezi n. sp., holotype female (a, e), paratype female (b – d). (a) rostrum, ventral; (b) urosome, ventral; (c) urosomites 1 and 2, dorsal; (d) genital double-somite, ventral; (e) leg 6, latero-ventral.

FIGURE 11. Halicyclops martinezi n. sp., holotype female. (a) antennule, lateral; (b) antenna, lateral.

FIGURE 12. Halicyclops martinezi n. sp., holotype female. (a) labrum; (b) mandible, lateral; (c) maxillule, lateral; (d) maxilla, lateral; (e) maxilliped, lateral.

FIGURE 13. Halicyclops martinezi n. sp., holotype female. (a) leg 1, posterior; (b) leg 2, anterior; (c) leg 3, anterior; (d) leg 4, anterior.

FIGURE 14. Halicyclops martinezi n. sp. (a) paratype male, habitus, dorsal; (b) allotype male, urosome, lateral.

FIGURE 15. Halicyclops martinezi n. sp., allotype male. (a) urosome, dorsal, (b) same, ventral; (c) labrum, ventral.

FIGURE 16. Halicyclops martinezi n. sp., allotype male, antennule, lateral.