Hydrobiologia 474: 41–55, 2002.© 2002 Kluwer Academic Publishers. Printed in the Netherlands.

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Records of Orthoclad species from the Darjeeling–Sikkim Himalayas ofIndia (Diptera: Chironomidae), with notes on their ecology

Niladri Hazra, Goutam K. Saha & Prasanta K. ChaudhuriDepartment of Zoology, University of Burdwan, Burdwan, 713 104, IndiaE-mail: chaudhuri_pk@yahoo.co.in(∗Author for correspondence)

Received 19 October 2000; in revised form 25 September 2001; accepted 6 November 2001

Key words: Chironomidae, Orthocladiinae, new records, Paracricotopus, Parametriocnemus, Paraphaenocladius,rheobiontic

Abstract

Life stages of orthoclad species, Paracricotopus spinicornis n.sp., Parametriocnemus ornatocornis (Kieffer) andthe immatures of Paraphaenocladius impensus albusalatus Chaudhuri & Sinharay are described from India. Abrief note on the ecology of the species is also given.

Introduction

In our survey of the chironomid midges of theDarjeeling–Sikkim Himalayas a number of adults andtheir immatures were collected. On rearing they wereidentified as three species belonging to three differ-ent genera, Paracricotopus Thienemann & Harnisch,Parametriocnemus Goetghebuer and Paraphaenocla-dius Thienemann. Prior to this study, the genera wererepresented from India by one, four and two species,respectively. In this paper, life stages of the species ofeach of the genera are described. Of these, the speciesof the last two genera are known as adults only fromAustralia and Saudi Arabia, respectively.

Materials and methods

Specimens were slide mounted after the techniquesimilar to that of Das Gupta & Wirth (1968). Thegeneral terminology follows Sæther (1980a) with ad-ditional terminology for adults, larva and pupa fromOliver & Dillon (1989). Lex & Pex refer to larval andpupal exuviae, respectively. Measurements of imma-tures and adults were taken with the aid of a compoundmicroscope and were expressed in micrometer (µm)except the body and wing which was in millimeter

(mm). Measurements were given as ranges with ‘n’ensuring the number of specimens observed.

Types and other specimens at present retained inthe Entomology Laboratory, Department of Zoology,University of Burdwan will be deposited to the Na-tional Zoological Collections, Calcutta, The NaturalHistory Museum, London and United States NationalMuseum, Washington D.C. in course of time.1. Paracricotopus spinicornis Hazra & Chaudhuri n.sp.

Etymology: The name ‘spinicornis’ derives fromthe presence of spinules in the thoracic horn of pupa.

Adult male (n = 5, unless otherwise stated).Total length 1.62–2.25; wing length 0.9–1.12; total

length / wing length 1.80–2.00; wing length / length ofprofemur 2.14–2.43.

Head: AR 0.28–0.37; length of flagellomeres (I–XIII): 26–44, 18–26, 18–26, 26–33, 29–37, 33–41,33–41, 33–41, 33–41, 33–41, 33–41, 33–41, 100–l59.Temporal setae 3–5, including 1–2 IV, 2–3 OV. Clyp-eus with 8–12 setae. Cibarial pump as in the Figure1; tentorium (Fig. 1) 150–165 long. Length of pal-pomeres: 15–22, 26–37, 37–55, 63–78, 67–122. CA0.61–0.64; CP 0.94–1.44.

Thorax (Fig. 2): Anteprontum well developedwith lobes in contact medially, lateral anteprontals 2;acrostichals uniserial, 7–15, dorsocentrals uniserial,

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Figures 1–5. Paracricotopus spinicornis n.sp. Adult male. Figure 1. Cibarial pump and tentorium; Figure 2. Thorax; Figure 3. Wing; Figure4. Hypogium; Figure 5. Gonostylus.

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8–12, prealars 3, supraalar 1; scutellum with 8–10setae.

Wing (Fig. 3): VR 1.11–1.19; CR 0.92–0.94; mem-brane transparent, veins not well distinct; brachiolumwith 1–3 setae; anal lobe weakly rounded; costal ex-tension 45–75 long; R4+5 ending slightly proximalto end of m3+4, Cu1nearly straight; squama with46 setae. Haltere basally blackish and apically lightbrown.

Legs: Spur of fore tibia 33–41 long, spurs of midtibia 11–15 and 14–21 long, hind tibia 29–39 and 18–25 long; width at the apex of fore tibia 29–38, midtibia 25–41, hind tibia 40–52; hind tibial comb with13 setae.

Leg lengths and ratios:

p1 p2 p3

fe 420–465 405–480 375–750

ti 450–525 420–480 450–540

ta1 315–375 195–240 240–285

ta2 225–255 105–120 142–165

ta3 188–210 90–98 135–146

ta4 105–135 45–53 57–65

ta5 75–83 52–60 57–66

LR 0.66–0.71 0.44–0.50 0.52–0.54

BV 1.94–2.44 3.48–3.72 2.67–3.03

SV 2.22–2.44 4.44–4.95 3.23–3.88

BR 1.58–2.00 2.20–3.33 2.50–4.66

Hypopygium (Fig. 4): Anal point distinct, poin-ted, 29–33 long with 2–3 strong lateral setae on eachside, apical part bare; gonocoxite 129–140 long, in-ferior volsella triangular with several micro– and mac-rosetae; gonostylus (Fig. 5) 62–74 long with weakpreapical crista dorsalis; lateral sternapodeme 62–74 long, coxapodeme 37–43 long and phallapodeme29–33 long; HR 1.75–2.11; HV 2.58–2.74.

Adult female (n = 3).Similar to male with usual sex differences. An-

tenna 5 segmented; AR 0.43–0.48. VR 1.08–1.09.Genitalia (Fig. 6): Tergite IX large, undivided

without caudal projection bearing 6–8 setae; vaginalopening U–shaped; coxasternapodeme overlapped orvery close to gonocoxapodeme; gonocoxite IX with3–4 strong setae; seminal capsule, sclerotized measur-ing 66–74 long by 44–52 wide; notum 114–118 long;cercus 70–72 long.

Pupa (n = 6).

Figure 6. Paracricotopus spinicornis n.sp. Adult female. Figure 6.Genitalia.

Total length 2.22–2.77. Pale brown in colour.Cephalothorax: Frontal setae 37–59 long on pre-

frons (Fig. 7). Ocular field with 1 stout, vertical83–103 long; median anteprontals 55–77 and 92–129long. Thoraic horn (Fig. 8) 195–255 long, 40–60wide, clubbed, covered with spinules and apparentcrease present; Thr 4.25–4.85. Anterior precornealseta 136–148 long, median precorneal Seta 103–120and posterior precorneal seta 35–42 long (Fig. 8).Dc137–51, Dc2 33–37, Dc315–20, and Dc422–37long; distance between Dc1and Dc284–93, betweenDc2 and Dc320–33, between Dc3and Dc45–7. Thoraxweakly rugulose.

Abdomen (Fig. 9): Tergites I–VIII withoutshagreen, tergite IX with few anterior shagreen; stern-ite I with postero- -lateral shagreen, sternites II–IVwith almost uniformly distributed shagreen, sterniteV with antero–median shagreen and caudal shagreen,sternites VII–VIII with uniform shagreen, sternite IXsmooth. Tergite II with posterior rows of hookletsarranged in a concave manner. Tergites IV–VI withmedian transverse rows of spines, tergites III–VIIIand sternites VI–VIII with posterior rows of spinesand spinules; tergite V as in the Figure 10. Conjunct-ives III/IV–V/VI with 2 rows of anteriorly directedspinules. Pedes spurii A present on sternites IV–VI.Apophyses distinct on segment II–VII. Segments II–VI each with 3 L setae, segments VII and VIII with 3

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Figures 7–11. Paracricotopus spinicornis n.sp. Pupa. Figure 7. Frontal apotome and prefrons; Figure 8. Thoracic horn and precorneal setae;Figure 9. Tergites; Figure 10. Tergites V; Figure 11. Anal lobe and male genital sac.

and 4 LS setae, respectively. Anal lobe (Fig. 11) 162–177 long and 159–174 wide with 5–7 setae in fringeand 14–17 apical spines, 3 anal macrosetae of aboutequal length, 140–155 long; genital sac 133–148 longin male and 118–148 in female, not extending bey-ond anal lobe in both sexes; G/F 0.76–0.83 in male

and 0.75–0.8 in female. ALR 2.00–2.09 in male and1.6–2.26 in female.

Larva (n = 5, 4th instar).Length of larvae 2.70–3.20. Body colour light

green, head capsule brown.

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Antenna (Fig. 12): AR 1.34–1.60, length of anten-nal segments (I–V) 44–48, 14–18, 6–8, 4.8–5.9, 2.6–3.8; distance of ring organ from the base 2.95–4.44;blade 24–30 long, shorter than flagellum; lauterbornorgan distinct, 5–7 long.

Labrum: S I (Fig. 13) simple with apical serrationsin most specimens or bifid at apex in some larvae,other setae simple; pecten epipharyngis consisting of 3broad, triangular scales. Premandible (Fig. 14) 51–66long with single apical tooth.

Mandible (Fig. 15): 100–140 long with 1 apical,4 inner and 1 false teeth; seta subdentalis 8–14 long,narrow, pointed; seta interna with 6 branches.

Maxilla (Fig. 16): Anterior lacinial chaeta notrectangular.

Mentum (Fig. 17): Width 77–81, single mediantooth 11–14 long, dome shaped; ventromental plateextending beyond the margin of outer mentum tooth;setae submenti located on middle half of submentum.

Body: Procercus (Fig. 18) 22–29 long, 14–18 widewith 7–11 long, curved, blackish basal spur and 2short median setae, preapical spur not developed; eachprocercus bearing 3 strong and 2 weak anal setae,longest 400–470 long. Supraanal seta 70–81 long.Posterior parapods 220–240 long with 10–11 claws.Anal tubules 209–235 long. Body setae strong, 75–90long.

Remarks: Male imago of this species is very sim-ilar to Paracricotopus niger (Kieffer) and P. millrock-ensis Caldwell (1985) in respect to gonocoxite length,shape of inferior volsella. Gonostylus of the presentspecies is nearer to P. glaber Sæther (1980b). AR,VR, CR and LR of male imago come closer to P.missilus Chaudhuri & Som (1998), and so also theAR, LR of female imago. The characteristics likethoracic horn, apical spines on anal lobe of pupa andthe larval features such as antenna, premandible andanal setae show close affinities with P. millrocken-sis: Mandible, premandible and mentum of larvaehave resemblances with P. glaber: Shagreen patternon sternites, mentum, submental setae are similar to P.missilus: In spite of the aforesaid similarities, the dif-ferences are so pronounced that the species in questionfavour for considering as a new member of Parac-ricotopus Thienemann & Harnisch with the followingcombination of characters:

Adult male: (i) Clypeus with 8–12 setae, (ii) AR0.28–0.37, (iii) scutellum with 8–10 setae, (iv) squamawith 4–6 setae, (v) anal point 29–33 long, pointed with2–3 lateral setae on each side and (vi) HR l.75–2.11.

Adult female: (i) AR 0.43–0.48, (ii) VR 1.08–1.09,(iii) gonocoxite IX with 3–4 strong setae, (iv) tergiteIX without caudal projection bearing 6–8 setae and (v)seminal capsule oval 66–74 long by 44–52 wide.

Pupa: (i) Thoracic horn 195–225 long, clubbedcovered with spinules, (ii) Thr 4.5, (iii) posterior pre-corneal seta very short, 35–42 long, (iv) Dc3and Dc4in a group, distance between them 5–7 (v) tergitesIV–VI with median transverse rows of spines, (vi) seg-ments VII and VIII with 3 and 4 LS setae, respectively,(vii) anal lobe with 5–6 setae in fringe and 14–15 ap-ical spines on each side and (viii) ALR 2.00–2.09 inmale and 1.6–2.26 in female.

Larva: (i) AR 1.34–1.60, (ii) S I mostly simplewith apical serrations or rarely bifid, (iii) seta submentilocated on middle half of submentum, (iv) only basalprocercal spur present and (v) 3 strong and 2 weak analsetae.

Ecology: The larva of P. spinicornis is rheobionticand prefers algal mats attached on rocks of slow tomoderately flowing perennial spring.

Material examined: Holotype ♂ with Lex and Pex[reared] (Type no. B.U. Ent. 240), Sikkim, Tadong,06–IV–1996, leg. N. Hazra. Paratypes 1 ♀ and 1 ♂with Lex and Pex [reared], data same as holotype; 3♂♂ and 1 ♀ [reared], Sikkim, Jorethang, 10–XI–1996,leg. N. Hazra; 2 ♂♂ with Lex and Pex [reared], WestBengal, Teestabazar, 08–Xl– 1996, leg. N. Hazra; 1 ♂and 1 ♀ with Lex and Pex [reared], West Bengal, TigerHill, 10–XI–1997, leg. N. Hazra.

2. Parametriocnemus ornaticornis (Kieffer)

Metriocnemus ornaticornis Kieffer, 1917: 225.

Parametriocnemus ornaticornis (Kieffer): Freeman,1961: 660.

Adult male (n =4).Total length 2.25–2.52; wing length 1.2–1.42; total

length / wing length 1.77–1.88; wing length / length ofprofemur 2.35–3.05.

Head: Eyes bare with 111–120 long dorsomedialextension. AR 0.41–0.46, length of flagellomeres (I–XIII): 33–37, 22–29, 25–30,29–33, 33–37, 33–37,36–38, 36–38, 36–38, 36–38, 37–41, 37- -41, 170–196; ultimate flagellomere bearing short, straight setaat extreme apex and 3–4 long curled setae near the tip.Temporal setae 6–10 including 1–2 IV, 4–6 OV, 1–2Po. Clypeus with 8–9 setae. Tentorium 80–111 long.Cibarial pump 107–162 long with well developed

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Figures 12–18. Paracricotopus spinicornis n.sp. Larva. Figure 12. Antenna; Figure 13. S I of labrum Figure 14. Premandible; Figure 15.Mandible; Figure 16. Maxilla; Figure 17. Mentum. Figure 18. Procercus.

cornua. Length of palpomeres: 18–26, 25–30, 66–89,77–103, 122–163. CA 0.56–0.77; CP 0.84–1.12.

Thorax (Fig. 19). Anteprontum well developedwith 2–3 lateral antepronotals; acrostichals 15–20beginning near anteprontum, dorsocentrals 14–25

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uniserial to biserial, prealars 5–6, scutellum with 10–15 large setae in single transverse row with 3–4 weaksetae anterior to this row.

Wing (Fig. 20): VR 1.06–1.08; CR 0.93–0.96;membrane with macrotrichia densely covering in theapical half of the wing, tending to form streaks alongthe veins; anal lobe moderately developed; brachiolumwith 1 seta; costal extension 75–90; R2+3runningclosely parallel to R4+5 and evanescent; R4+5 endingopposite to end to R3+4; squama with 4–6 setae.

Legs: Spur of fore tibia 33–37 long, spurs of midtibia 18–25 long and hind tibia 37–44 long; width atthe apex of fore tibia 29–33, mid tibia 33–37 and hindtibia 37–44; hind tibial comb with 9–12 setae.

Leg lengths and ratios:

p1 p2 p3

fe 510–615 495–585 510–600

ti 555–660 480–540 600–690

ta1 450–540 270–300 360–435

ta2 240–285 120–135 165–210

ta3 165–195 75–90 135–157

ta4 120–135 60–68 75–90

ta5 60–75 55–63 60–75

LR 0.81–0.82 0.55–0.56 0.60–0.63

BV 2.58–2.63 4.00–4.01 3.24–3.37

SV 3.08–3.14 5.09–5.13 4.00–4.11

BR 2.20–2.25 2.40–4.00 3.00–3.83

Hypopygium (Fig. 21): Anal point 37–44 long, 3–4 strong lateral setae on each side, apical part bare;gonocoxite 148–155 long; inferior volsella broadlyrounded, gonostylus 63–70 long with small crista dor-salis and an apical dark megaseta 6–10 long; sterna-podeme straight 36–40 long, phallapodeme 75–83long, coxapodeme 19–23 long; HR 2.21–2.37; HV3.22–3.63.

Adult female (n = 3).Similar to male with usual sex differences. An-

tenna 5 segmented, AR 0.27–0.29. VR 1.00–1.05.Genitalia (Fig. 22): Tergite IX (Fig. 23) with a

distal, shallow median invagination and 14–18 strongsetae arranged in 2 rows posteriorly, vaginal open-ing nearly inverted U shaped with lateral margincontinuous with gonocoxapodeme; coxasternapodemeslender overlapping gonocoxapodeme; gonocoxite IXwith 5–7 setae; seminal capsules feebly sclerotized

measuring 55–77 by 37–52; notum 66–85 long; cercus41–55 long.

Pupa (n=5).Total length of exuviae 2.77–3.51.Cephalothorax: Frontal apotome (Fig. 24) without

anteromedian warts. Male antennal sheath withoutrow of minute pearls above pedicel. Postorbitalpresent; median antepronotals 93–111 and 66–93long. Thoracic horn (Fig. 25) ballon like, rugose,270–330 long with scattered spinules; Thr 3.81–5.14.Anterior precorneal 55–60, median precorneal 96–107 and posterior precorneal 50–56 long. Dc116–19,Dc2 14–16, Dc311–18, and Dc47–11 long; distancebetween Dc1and Dc211–18, between Dc2and Dc392–111, between Dc3 and Dc448–52. Thorax rugulose.Wing sheath (Fig. 26) with 2–3 rows of pearls andoccasionally apparent crease at the base.

Abdomen (Fig. 27): Tergites I–VIlI with shagreen,IV with lateral shagreen, IX with shagreen; sterniteI with almost uniform shagreen, II, V, VI, VII withmedian shagreen, III–IV with uniform shagreen, VIII–IX without shagreen; sternites IV–VIII and tergitesII–VIII with caudal spines; tergite I with polygons.Pedes spurii B digitiform, 59–85 long. Apophyseswell developed. Segments II–VIII with hair like Lsetae. L1and L2adjacent in segments II–VII, but dis-tant in segment VIII. Anal lobe both in male (Fig.28) and female 210–235 long and 240–255 wide withsparse fringe of 8–9 lamelliform setae as long as analmacrosetae and 15–17 apical spines; 3 macrosetaeof about equal length 150–165. Genital sac 225–240 long, barely overreaching anal lobe in male and105–120 long in female. G/F 1.02–1.04 in male and0.5–0.51 in female. ALR 1.75–1.84 both in male andfemale.

Larva (n = 4).Total length of larvae 4.44–4.62.Antenna (Fig. 29): AR 1.73–2.17, length of an-

tennal segments (I–V): 40–63, 15–18, 2–3, 4–5, 2–3;segment IV longer than III; ring organ at basal third,distance of ring organ from the base 3–5; blade 22–29 long, little shorter than flagellum; lauterborn organalmost equal to segment III.

Labrum: S I plumose (Fig. 30), S II single (Fig.31), other S setae simple; chaetae simple; chaetulaelaterales simple; premandible (Fig. 32) 50–60 longwith 2 apical teeth.

Mandible (Fig. 33): 90–120 long with 1 apical,4 inner teeth; seta subdentalis 14–18 long, narrow,pointed; seta interna with 6 plumose branches.

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Figures 19–21. Parametriocnemus ornaticornis (Kieffer). Adult male. Figure 19. Thorax; Figure 20. Wing; Figure 21. Hypopygium.

Maxilla (Fig. 34): Anterior lacinial chaeta shorterthan other lacinial chaetae.

Mentum (Fig. 35): 81–96 width; ventromentalplate 50–55 long, 16–19 wide, extending beyond themargin of the outer mental tooth.

Body (Fig. 36): Procercus 22–29 long, 14–18 widewith 6 anal setae. Anal tubules longer than posteriorparapods.

Remarks: The species was described as a mem-ber of Metriocnemus van der Wulp from Australia byKieffer (1917). Freeman (1961) made generic trans-

fer of the species to Parametriocnemus Goetghebuer.Indian specimens studied in this venture fully con-form with its counterparts of Australia in respect tomorphology.

Adult male: (i) Colouration in body, (ii) clypeuswith 8–9 setae, (iii) AR 0.41–0.46, (iv) scutellum with10–12 setae, (v) macrotrichia dense in the apical halfof the wing and forming streak along the veins, (vi)squama with 4–5 setae, (vii) LR10.81–0.82, LR20.55–0.56 and LR30.60–0.63 respectively, (viii) anal point

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Figures 22–23. Parametriocnemus ornaticornis (Kieffer). Adultfemale. Figure 22. Genitalia; Figure 23. Tergite. IX.

with 3–4 lateral setae on each side but apex bare and(ix) HR 2.21–2.37.

Adult female: (i) Tergite IX with a distal, shal-low, median depression having 14–18 setae and (ii)gonocoxite IX with 9–10 setae.

Pupa: (i) Thoracic horn 270–330 long, ballon like,rugose with scattered spinules, (ii) wing sheath with2–3 rows of pearls, (iii) median precorneal longer byabout a half than the remaining ones, (iv) tergites II–VIII and sternites IV–VIII with caudal spines, (v) anallobe with 15–17 apical spines and 8–9 lamelliformsetae as long as anal macrosetae and (vi) genital sacin male barely overreaching anal lobe.

Larva: (i) AR 1.95, (ii) antennal segment IV longerthan III, (iii) antennal blade shorter than flagellum, (iv)premandible with 2 apical teeth and (v) anal tubuleslonger than posterior parapods.

Distribution: Australia and India.

Ecology: The larva of Parametriocnemus ornatic-ornis is rheobiontic and lives in the slow to moderatelyflowing springs, often attached with stones.

Material examined: 1 ♂ with Pex [reared], Sikkim,Tadong, 06–III–1996, leg. S. K. Pradhan; 3 ♀♀ and 3♂♂ with Lex and Pex [reared], Sikkim, Tadong, 09–IV–1996, leg. N. Hazra.

3. Paraphaenocladius impensus albusalatus Chaudhuri& Sinharay

Paraphaenocladius impensus albusalatus Chaudhuri& Sinharay, 1987: 95.

Paraphaenocladius impensus albusalatus Chaudhuri& Sinharay; Sæther & Wang, 1995: 59.

Paraphaenocladius trichialis Chaudhuri & Sinharay,1987: 99; Sæther & Wang, 1995: 59.

Paraphaenocladius croceus Chaudhuri & Bhat-tacharyay in Chaudhuri, Bhattacharyay & Dutta,1989: 316; Sæther & Wang, 1995: 59.

Paraphaenocladius distinctus Chaudhuri & Bhat-tacharyay in Chaudhuri, Bhattacharyay & Dutta,1989: 317; Sæther& Wang, 1995: 59.

Paraphaenocladius amamirobustus Sasa, 1990: 131;Sasa & Okazawa, 1992: 157; Sæther & Wang, 1995:59.

Pupa (n = 1).Total length 2.59.Cephalothorax: Frontal apotome (Fig. 37) with

anteromedian, double sclerotized short crease. Ocularfield with postorbital 22 long, median antepronotals 89and 29 long, lateral antepronotals 22 long each veryclose together. Thoracic horn (Fig. 38) 118 long, 15wide, 3.19 x as long as terminal seta on anal lobe,slender with scattered spinules mostly at apex, Thr7.86. Anterior precorneal 74 long, median precorneal59 long and posterior precorneal 44 long (Fig. 38);Dc115 long, Dc252 long, Dc3and Dc418 long each;distance between Dc1and Dc274, between Dc2andDc322, between Dc3and Dc424. Wing sheath (Figs39–40) with nose, with 49 pearls.

Abdomen (Fig. 41): Tergites II–VI with extensiveshagreen, less extensive on VII–VIII; sternites I–IIIand IV without shagreen, sternites IV–VIII with pos-teromedian shagreen; tergites VI–VIII with posterior

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Figures 24–28. Parametriocnemus ornaticornis (Kieffer). Pupa. Figure 24. Frontal apotome and prefrons; Figure 25. Thoracic horn andprecorneals; Figure 26. Tip of wing sheath; Figure 27. Tergites; Figure 28. Posterior part of tergite VIII anal lobe and male genital sac.

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Figures 29–36. Parametriocnemus ornaticornis (Kieffer). Larva. Figure 29. Antenna; Figure 30. S I of labrum; Figure 31. S II of labrum;Figure 32. Premandible; Figure 33. Mandible; Figure 34. Maxilla; Figure 35. Mentum; Figure 36. anal end.

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Figures 37–42. Paraphaenocladius impensus albusalatus Chaudhuri and Sinharay. Pupa. Figure 37. Frontal apotome; Figure 38. Thoracichorn and precorneals; Figure 39. Tip of wing; Figure 40. Enlarged nose of wing; Figure 41. Tergites; Figure 42. Anal end.

rows of small spines. Pedes spurii B weak. SegmentsII–VIII with 3 short L setae. Anal lobe (Fig. 42) 111long and 103 wide with 1 terminal seta 37 long and2–3 apical spines. Genital sac of male 185 long, over-reaching anal lobe by 74. G/F in male 1.66. ALR2.14.

Larva (only head capsule retained).Antenna (Fig. 43): AR 0.78; lengths of antennal

segments (I–V) 15, 9, 3, 4, 3; distance of ring organfrom the base 7; blade 17 long, shorter than flagellum;lauterborn organ 4 long.

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Figures 43–48. Paraphaenocladius impensus albusalatus Chaudhuri and Sinharay. Larva. Figure 43. Antenna; Figure 44. S I of labrum; Figure45. Premandible; Figure 46. Mandible; Figure 47. Maxilla; Figure 48. Mentum.

Labrum: S I plumose (Fig. 44), S II, S III and S IVsingle and strong; chaetae simple; premandible (Fig.45) 52 long.

Mandible (Fig. 46): 89 long with 1 apical and 4inner teeth; seta interna with 7 serrate branches; setasubdentalis 4 long, apex blunt.

Maxilla (Fig. 47): Anterior lacinial chaeta broad–based than the other lacinial chaetae.

Mentum (Fig. 48): 90 width; median tooth divided;distance of seta submenti from occipital margin 48.

Remarks: Chaudhuri & Sinharay (1987) describedthe male imago of Paraphaenocladius impensus al-busalatus from Darjeeling, West Bengal and Tura,Meghalaya. The present specimen encountered in thestudy fully agrees with the descriptions of Chaudhuri& Sinharay (1987). Pupa is similar to P. impensus s.str. with 1 terminal seta on the anal lobe, wing sheathhaving both nose and pearls. Larva also appears to besimilar to impensus group after Sæther & Wang (1995)

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in respect to divided median mental tooth. However,diagnostic features of the subspecies are:

Adult Male: (i) AR 0.45–0.53, (ii) LR10.71–0.81,LR20.54–0.58, LR30.67–0.72 and (iii) squama with4–6 setae.

Pupa: (i) Thoracic horn 3.19 x as long as terminalseta on anal lobe, (ii) wing sheath with 49 pearls andnose, (iii) anal lobe with 37 long single terminal seta,(iv) 2–3 apical spines on anal lobe, (v) genital sacoverreaching anal lobe by 74, (vi) G/F in male 1.66and (vii) ALR. 2.14.

Larva: (i) AR 0.78, (ii) premandible 52 long, (iii)mandible 89 long with 7 branches in seta interna and(iv) median tooth divided without lateral notches.

Distribution: Saudi Arabia and India: West Bengaland Meghalaya.

Ecology: Larva of Paraphaenocladius impensusalbusalatus inhabits in bryophytes attached on rockswhere a very thin film of water is flowing keeping thehabitat moist.

Material examined: 1 ♂ with Lex and Pex [reared],West Bengal, Teesta Bazar, 09–IV–1997, leg. N.Hazra. Paratypes: 3 ♂♂ West Bengal, Darjeeling,l4–IX–1970, leg. P K. Chaudhuri.

Biogeographical significance

Our present knowledge is not sufficient to focus onthe zoogeography of the chironomids. An examina-tion of the bibliography of Chirnomidae demonstratesour restricted knowledge of broad distribution patterns(Cranston & Oliver, 1987). Any discussion of zoogeo-graphic relationship is highly speculative (Roback &Coffman, 1989). New findings may upset the distri-butional range of a species. Regional or local fauna isvaluable in faunistic studies and is a suitable tool foranalyses of biogeographical relationship (Cranston &Judd, 1989). The genus Paracricotopus Thienemann& Harnisch has only a Holarctic and Oriental distri-bution and is very poorly represented in the Orientalregion. Prior to this study, Roback & Coffman (1987)have described some larvae and an unassociated pupafrom the Nepal Alpine zone. Another Oriental recordof the genus is from Indonesia through pupal exuviae(Ashe et al., 1987). Chaudhuri & Som (1998) de-scribed Paracricotopus missilus as the first memberof the genus Paracricotopus from India and P. spi-nicornis n.sp. proposed here is another record fromIndia and endemic at present. Discovery of more spe-cies will make proper assessment of the genus. The

genus Parametriocnemus Goetghebuer has a world-wide distribution and the genus ParaphaenocladiusThienemann is known from all zoogeographical re-gions except Australasia. The affinities of the faunaof the study area with Australia reflect typical fea-ture of Gondwanaland ancestry. Prior to the break–upof the southern continents, India occupied a positionbetween southern Africa and western Australia (Asheet al., 1987). There is evidence of Gondwanaland con-nections between Australia, South America and NewZealand (Edward, 1989) and the continuous land con-nection from Australia through Antarctica to SouthAmerica finally broke at least 45 million years B.P.(Ashe et al., 1987). The presence of same generaand species in India, Australia and Africa indicatesthat they are at least 100 million years old or morewhen these regions were connected with each other.Again similarities with Palearctic elements also re-flect Laurasian ancestry. The Indian land mass afterbreak moved northward by gradually obliterating theTethys sea and collided with Laurasian landmass. Asa consequence of the intense squeezing out of theTethyan geosyncline between Laurasia and the Indianpeninsular block the great Himalayan range emergedout. Two faunistic gateways – Assam or eastern gate-way and northwestern gateway arose through whichfaunal influx took place (Mani, 1974). Thus, the Indianchironomid fauna contain Gondwanaland, Afrotrop-ical and later entered Holarctic elements which movedsouthward and some Oriental elements entered fromnortheast (Roback & Coffman, 1989). Occurrenceof same species in different zoogeographical regionssupport the unifying theory – ‘plate tectonics’. There-fore, the study area is immensely important from thestandpoint of biogeography.

Acknowledgements

We are thankful to the Department of Science & Tech-nology, Govt. of India, New Delhi for providing fundfor the project and to the Head of the Departmentof Zoology, University of Burdwan and Postgradu-ate Department of Zoology, Darjeeling Govt. Collegefor laboratory facilities. We are also indebted to DrXinhua Wang, Department of Biology, Nankai Univer-sity for kindly reading the manuscript and renderingvaluable comments.

55

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