Simulium (Hebridosimulium) laciniatum Edwards, 1924

Craig, Douglas A., Currie, Douglas C., Hunter, Fiona F. & Spironello, Mike, 2006, A taxonomic revision of the southwestern Pacific subgenus Hebridosimulium (Diptera: Simuliidae: Simulium), Zootaxa 1380 (1), pp. 1-90 : 53-60

Simulium (Hebridosimulium) laciniatum Edwards

( Figs. 1b , 4b , 5g , 6c , 9h , 11f , 13g , 15b , 16g , 18g , 20g )

Simulium laciniatum: Edwards 1924:572

Simulium jolyi: Edwards (1932:103) not Roubaud 1906

Hebridosimulium jolyi: Grenier & Rageau (1961: 96) not Roubaud 1906

Simulium (Hebridosimulium) jolyi: Crosskey (1967: 30) in part not Roubaud 1906

Simulium (Hebridosimulium) laciniatum: Dumbleton (1973: 453) revalidation

Simulium (Hebridosimulium) jolyi laciniatum: Crosskey (1974: 150)

Simulium (Hebridosimulium) laciniatum: Craig (1987: 383) ; Crosskey (1987: 451); Crosskey (1989: 223); Crosskey & Howard (2004: 29)

Types

Holotype. Adult. Pinned female. Label data – “W Greenwood/ Mt Evans / Lautoka, Fiji / 2500 ft. 11.5.19.” ( BM) . Paratype. Adult. Pinned female. Label data – “W Greenwood/ Mt Evans. Fiji / 18.6.1922 ” ( BM) .

Diagnosis

Large species. Adults: black; pleural membrane with distinct yellow hairs; legs markedly bicolourous. Pupa: 8 gill filaments, shorter and thicker than in other species; branching pattern (2+1)+2+2+1. Larva: hypostomal teeth poorly developed; postgenal cleft with marked anterior extension; posterior abdomen steatopygous; dorsal tubercles absent.

Redescription

Adult female (based on numerous topotypical specimens in alcohol). Body: head blackish brown, thorax dark brown, abdomen blackish brown; total length 2.6–3.2 mm. Head: width 0.94–1.0 mm; depth 0.58–0.64 mm; postocciput black, vestiture of dense, black hairs; frons thickly golden haired and pruinose, slightly protruded; frons-head ratio (narrowest width of frons: greatest width of head) 1.0:5.8. Eye: interocular distance 0.17 mm; ommatidia 0.020 mm in diameter; ca 40 rows across and down at mid-eye. Clypeus: 0.21–0.28 mm wide; concolourous with frons; vestiture of dense black and pale hairs, less so in specimens from Taveuni. Antenna: length 0.51–0.61 mm; flagellomeres grayish yellow; slightly darker basally and apically, scape and pedicel pale yellow. Mouthparts: length 0.3 times head depth; mandible with 30–35 markedly fine inner teeth; lacinia with 15 inner teeth and 10 outer teeth; maxillary palpus with all articles evenly dark brown, proportional length of 3rd, 4th, and 5th articles 1.0:0.9:1.4; sensory vesicle markedly elongate, ca. 0.3 times width of 3rd article, opening 0.8 times as wide as vesicle. Thorax: length 1.3–1.5 mm; width 1.0– 1.2 mm; postpronotal lobes markedly paler than scutum; scutum evenly medium brown in dry specimens, but 2 lateral vittae in alcohol specimens, vestiture of dense, very fine pale hairs, longer dark hairs posteriorly; more evenly coloured and less hairy in Taveuni specimens; scutellum more or less concolourous with scutum, vestiture of long black hairs and pale hairs laterally, apical angle 125°; postnotum concolourous with scutum; pleuron evenly dark brown; pleural membrane slightly paler and with distinct yellow hairs ( Fig. 4b ). Wing: length 2.7–2.9 mm; width 1.2 –1.4 mm. Legs: coxae light brown; trochanters paler; fore leg femur light brown, remainder of leg black; mid leg femur darker brown with dense black vestiture, remainder of leg as for fore leg; hind leg femur as for mid leg, tibia pale basally, tarsus pale except for calcipala, tarsomere black. Abdomen: overall black; vestiture of dense silver hairs, long laterally, with few black hairs; basal scale black with golden hairs; hairs dark and sparser in specimens from Taveuni. Genitalia ( Fig. 5g ): median region of sternite VIII moderately depressed and pale medially; hypogynial valves with vestiture of sparse short hairs; median edges concave, short, membranous apical extension cone-shaped and posteriorly directed; genital fork stem narrow, lateral arms with small clear region, anteriorly directed apodeme cone-shaped; anal lobes rounded with few longer hairs posteriorly, anterior anterolateral apodeme not well developed, anteromedian concavity distinct with numerous hairs; cercus broad; spermatheca ovoid, reticulate pattern, moderately pigmented.

Adult male (based on numerous topotypical specimens in alcohol). Body: overall dark brown to black; total length 2.7–3.5 mm. Head ( Fig. 1b ): width 0.86–1.2 mm; depth 0.71–0.82 mm. Eyes: upper ommatidia dark orange, large, 0.057 mm in diameter, ca. 13 across and 16 down; lower ommatidia brown, 0.019 mm in diameter, ca. 26 across and 35 down. Clypeus: dark brown, pruinose 0.17 times as wide as head; vestiture of medium and short hairs laterally. Antenna: total length 0.66–0.70 mm; flagellomeres light yellow, scape, pedicel, and base of first flagellomere slightly darker than remainder; first flagellomere slightly longer than remainder. Mouthparts: short, length 0.2 times head depth; mandibles insubstantial, finely tapered with apical hairs; lacinia broad basally, finely tapered apically with terminal hairs, some tooth-like; palpus dark, 0.58 mm long, proportional lengths of 3rd, 4th, and 5th articles 1.0:1.4:1.6, 3rd article distinctly hairy, sensory vesicle barrel shaped, occupying 0.33 times width of article, opening 0.33 times width of vesicle. Thorax: length 1.2–1.4 mm; width 0.8–1.1 mm; broadest anteriorly; postpronotal lobes and scutum evenly medium brown; vestiture of short pale hairs often rubbed clear; scutellum lighter than scutum, apical angle distinctly obtuse; vestiture of markedly long stiff black hairs laterally, interspersed with paler hairs; postnotum concolourous with scutum; pleuron concolourous with scutum. Wing: 2.4–2.6 mm in length, 1.3–1.5 mm at maximum width. Legs: markedly bicolourous, tarsi and tibial apices dark brownish black, remainder yellow or reddish yellow; pretarsal claws with ca. 25 grappling hooks dorsally. Abdomen: anteriorly yellowish, remainder brownish black, vestiture of dense fine yellow hairs, markedly longer laterally; basal scale with markedly long, pale yellowish hairs. Genitalia ( Fig. 6c ): gonocoxa 1.3 times longer than basal width, vestiture of numerous substantial hairs, anterolateral apodeme well developed; gonostyle approximately 2.5 times longer than basal width, subequal in length to gonocoxa, distinct mediobasal strengthening ridge; ventral plate small, sloped laterally, proximal arms distinctly curved medially and tapered; median keel slightly angulate apically and laterally, stem narrow, vestiture of markedly small, evenly spaced hairs; parameral spines as for other species; dorsal sclerite broadly rounded apically, less V-shaped than other species; median sclerite short, slightly longer than apical width. Cerci: distinct.

Pupa (based on numerous topotypical specimens in alcohol). Body length: 2.8–3.8 mm. Gill ( Fig. 9h ): maximum length 1.28 mm, 8 filaments occasionally 9th as stump, evenly thick, light grey; petioles short, branching pattern (2+1)+2+1+2. Head and thorax with evenly distributed sparse, dark brown rounded granules. Cocoon: markedly boot shaped, anterior collar well raised above substrate, occasionally lower, opening equal to, or slightly narrower than, cocoon base, with marked edge, not flared laterally.

Larva (based on numerous topotypical mature last-instar larvae). Body ( Fig. 11f ): total length 6.3–7.9 mm; female evenly mottled gray, male yellowish-gray with paler intersegmental regions. Head ( Fig. 13g ): female medium to dark brown posteriorly extended anteriorly to apotome, males with posterior pigmentation lighter and apotome pale; width 0.62–0.71 mm; length 0.79–0.96 mm; distance between antennal bases 0.33–0.43 mm; lateral margins of head subparallel; ecdysial lines straight, diverged strongly posteriorly; head spots not distinct, anteromedial spots slightly positive, posteromedial and anteromedial spots similarly, but surrounded with pale aureole, posterior head spots negative; anterior genae pale, darkly pigmented posteriorly ( Fig. 15b ); posterior edge of apotome not emarginated, postocciput not extended between cervical sclerites and apotome. Antenna: evenly pale; total length 0.58 mm; distal article 0.24 times as long as basal articles, extended well beyond labral fan stalk. Labral fan: stalk moderately pigmented, anterior palatal bar moderately well developed; 45–50 fine rays, 0.74 mm in length, 8–10 rays less substantial; microtrichia markedly fine and elongate, 2 time longer than ray width, pattern distinct, with 6 or 7 shorter microtrichia between those longer. Postgenal cleft ( Fig. 16g ): narrowly V-shaped, edges straight. Postgenal bridge: 0.3 times as long as cleft depth; genae evenly pigmented light brown, posterolateral elongated muscle spots positive. Hypostoma ( Fig. 18g ): overall broadly cone-shaped; ratio 6.6; median tooth and lateral teeth poorly developed, latter teeth broad and subequal in length to median tooth; sublateral teeth very small; paralateral teeth and lateral serrations essentially absent; 9–11 very substantial hypostomal setae per side (12 or 13 in Kadavu larvae). Mandible ( Fig. 20g ): all apical teeth well developed; 3 or 4 substantial spinous teeth, gap small but distinct; serration and sensillum distinctly separated, but not markedly developed. Abdomen: thorax and anterior abdomen subequal in width, expanded gradually posteriorly; moderately steatopygous. Posterior circlet: directed posteriorly; 160–165 rows of hooks; 20–25 hooks per row (total ca. 3,700).

Additional material examined

Kadavu. Solodamu , E178.11° S19.06°, alt. 128m, 25.viii–23.x.2003. Coll. H. Erwin, E. Schlinger, M. Tokota’a (3 females, 1 male; FBA 010408. BPBM) . Kadavucoro Village , Wailea Waterfall, S19.03674° E178.37830°, alt. 10m, 27.xi.2004. Coll. D. & R. Craig (larvae, pupae; DAC) . Nacomoto Village , Lambasa Waterfall, S19.04535° E178.35305°, alt. 100m, 28.xi.2004. Coll. D. & R. Craig (larvae; DAC) . Matava Resort , S19.04507° E178.39946°, alt. 33 m, 28.xi.2004. Coll. D. & R. Craig. Attempting to bite (2 females; DAC) . Ovalau. Mt. Vuma, 700’, vii.14.38. Coll. E. C. Zimmerman (female; BPBM) . Draiba Trail , alt. 600–800 ft. viii.8.38. Coll. E. C. Zimmerman (4 females; BPBM) . Lovoni Val. alt. 50– 200 m. 27.xii. 69. Coll. N. H. L. Krause (2 females; BPBM) . Levuka , alt. 0– 200 m.?.xii.78. Coll. N. H. L. Krause (7 females; BPBM) . Levuka , Totonga Creek, alt. 70m alt., 17.viii.1980. Coll. D. A. Craig (larvae, pupae, reared adults; DAC) . Waitovu Village , stream cascade, S17.66545° E178.82551°, alt. 50–74 m, 2.xii.2004. Coll. D. & R. Craig (larvae, pupae; DAC) . Near Rukuruku , Stream junction, S17.65023° E178.76643°, alt. 76m, 2.xii.2004. Coll. D. & R. Craig (larvae, pupae; DAC) . Taveuni. Waiyevo. 21.vi.1924. Coll. H. S. Evans. (female; BM) . Alt. 0–100m, i.1972. Coll. N. H. L. Krause (2 females; BPBM) . Caukadrove Prov. Devo Peak Radio Tower. S 16° 51’ E 179° 58’, alt. 1200m, 10–17.x.2002. Malaise in rain forest. Coll. M. E. Irwin, E. I. Schlinger, M. Tokota’a. (14 females, male (slightly lighter, smaller and less hairy than other males in Fiji); FBA027946. BPBM) . Caukadrove Prov. Devo Forest reserve . S16° 50’ E179° 59’, alt. 800 m, 10–17.x.2002. Malaise in rain forest. Coll. M. E. Irwin, E. I. Schlinger, M. Tokota’a. (adults; FBA 027947 . BPBM) . Devo Peak Radio Tower , W179.97° S16.85°, alt. 1200m, 2–10.x.2002. Coll. M. E. Irwin, E. I. Schlinger, M. Tokota’a (1 female, missing wings; FBA021367. BPBM) . 13–20.x.2002. Coll. M. E. Irwin, E. I. Schlinger, M. Tokota’a (7 females. FBA020047. BPBM) . 25.ix–2.x.2002. Coll. M. E. Irwin, E. I. Schlinger, M. Tokota’a (4 females. FBA012575. BPBM) . Waitavala Water Slides , S16.79613° W179.99058°, alt. 45m, 17.xi.2004. Coll. D. & R. Craig (larvae, pupae; DAC) . Wainibau Falls , S16.86596° W179.90589°, alt. 30m, 18.xi.2004. Coll. D. & R. Craig (larvae; DAC) . Small waterfall 30 mins. on track from Lavena. S16.87089° W179.89072°, 18.xi.2004. Coll. D. & R. Craig (larvae; DAC) . Above Waitavala Water Slides , S16.79720° W179.99064°, alt. 60m, 19.xi.2004. Coll. D. & R. Craig (larvae, pupae; DAC) . Devo Peak , Trib. Wairiki Str., S16.81939° W179.99456°, alt. 350m, 20.xi.2004. Coll. D. & R. Craig (larvae, pupae; DAC) . Vanua Levu. Savusavu , alt. 100m,?. iii.1978. Coll. N. Krause (female; BPBM) . Cascade , 2 km towards Savusavu from Nambalembala, alt. 10m, 21.viii.1980. Coll. D. A. Craig (larvae; DAC) . Cross Island Road, 1 st cascade, 21.viii.1980, alt. 270m, Coll. D. A. Craig (larvae, pupae; DAC) . Near Savusavu , alt. 300m, 15.vii.1980. Coll. T. K. Crosby & P. A. Ryan. Basasega Crk. alt. 100m, 16.vii.1980. Coll. B. Cowey (larvae; DAC) . New Waisala Rain Forest Waterfall, Ravini Stream , Trib. of the Narakariwai River. 27 km from Savusavu, S16.65305° E179.22107° (est.), alt. 95–170m, 23.xi.2004. Coll. D. & R. Craig (larvae, pupae; DAC) . Savusavu Bay west road, Nakasa Water Fall, S16.67770° E179.19881°, alt. 90m, 25.xi.2004. Coll. D. & R. Craig (larvae, pupae; DAC) . Viti Levu . Mt. Lautoka, 1.v.1919. Coll. W. Greenwood (female; BM) ; 10.v.1919. Coll. W. Greenwood (2 females; BM) . Korovou , Tailevu, viii.1937. Coll. J. M. Valentine (female; BPBM) . Navia Mill , nr Nadarivatu, alt. 2500’, ix.17.1938. Coll. E. C. Zimmerman (female; BPBM) ; alt. 800–900m, 3.iv.1973; alt. 700–800m, 29.iv.1973; Coll. N. H. L. Krause (4 females; BPBM) . Nadarivatu , ix.3.1938; alt. 3700’, ix.10.1938; alt. 2700’, ix.13.1938; viii.31.1938. Coll. E. C. Zimmerman (5 females; BPBM) ; alt. 300’, 7.iii.54. Coll. M. Laird (female; BM); alt. 850m, 8–13.iii.1963. Coll. C. M. Yosimoto (2 females; BPBM) ; alt. 810m, vi.27.viii.4.1958. Coll. B. Malkin (female; BPBM) . Suva , 1955. Coll. H. W. Simmonds (3 females; BM) . Nausori Highland , alt. 500–700m, 1.x.70. alt. 500– 600m. 9.xi.1971. Coll. N. L. H Krause (8 females; BPBM) . Tholo-i-Suva. ?. i.1958. Coll. N. H. L. Krause (female; BPBM) ; 15.xi.1970. Coll. H. S. & G. S. Robinson (1 female, 2 males; BM) , 21.xii.1970, Coll. H. S. & G. S. Robinson (larvae, pupae; BM) . Nandala Riv. , alt. 2,400’, 13.vi.1971. Coll. M. E. & N. H. Hynes (larvae, pupae adults; BM) . Monasavu Riv. , nr Nadarivatu.?. ix.1978. Coll. M. A. Rao (larvae, pupae, adult; BM) . Nanuku Crk , alt. 700m, 2.vi.1980. Coll. B. Cowey and P. A. Ryan (larvae, biting females; DAC) . Tholo-i-Suva , upper stream 14.viii.1980. Coll. D. A. Craig (pupae, adults; DAC) ; lower stream 15.viii.1980. Coll. D. A. Craig (pupae, adults; DAC) ; 8.ix.1984, 23.viii.1984. Coll. B. S. Batson (larvae, pupae; DAC) . Nasivis R, trib, cascade nr, Waikumbukumba Vill , alt. 20m, 24.viii.1980. Coll. D. A. Craig (larvae, pupae; DAC) . Nakorowabama R, trib, 27.5 km from Suva , alt. 40m, 17.viii.1980, Coll. D. A. Craig (larvae, pupae, reared adults; DAC) . Kings Highway 0.1 km South, Wailota No. 1, 22.viii.1980. Coll. D. A. Craig (larvae, pupae, reared adults; ANIC, DAC. HT) . Nadarivatu , Tumbeindreketi Creek, alt. 633m, 23.viii.1980. Coll. D. A. Craig (larvae, pupae; DAC) . Lautoka , Vitonga Crk, alt. 150m, 24.viii.1980. Coll. D. A. Craig (larvae, pupae, reared adults; DAC) ; 29.vi.1981. 26.xi.1998 Coll. D. A. Craig (larvae, pupae, reared adults; DAC) . Lami , alt. 20–200m,?. iii.1976; alt. 0–200m,?. ii.1977; alt. 0–100m,?. iii.1978; alt. 0–200m,?. ii.1981; alt. 0–200m,?. iii.1984; Coll. N. H. L. Krause (6 females; BPBM) . Monasavu , alt. 81m, 9.x.1980, 24.x.1980. Coll. B. Cowey (larvae; DAC) . Nadarivatu , Waikubkukubu creek, “Governor’s pool”, 7.iii.1981. Coll. M. Goettel (larvae, pupae, adults; DAC) . Nadarivatu , Nadala Creek, 8.iii.1981. Coll. M. Goettel (larvae, pupae; DAC) . Namosi Rd , 8 km N Queens Highway, alt. 320m. 3–7.xi.1981. Coll. B. H. & W. E. Gagne (8 females; BPBM) . Wainimala R. trib, 10.ix.1984. Coll. B. S. Batson (larvae; DAC) . Waindina R. 21.viii.1984. Coll. B. S. Batson. (larvae, pupae; DAC) . Wainalithi Riv. , trib. 6.ix.1984. Coll. B. S. Batson (larvae, pupae; DAC) . Waivaka , Waindwa R, trib, 8.ix.1984. Coll. B. S. Batson (larvae; DAC) . Naitisiri Prov. , Logging Rd, below Mt. Nakobalevu. E178° 25’, S 18° 13’, alt. 340m. 22.ix.2002. Colls. E. I. Schlinger, Moala (1 female, 1 male; FBA 027948, BPBM) . Mt. Nakobalevu , Logging road behind Suva; in rain forest. S18° 3’, E 178° 25’. alt. 340m. 13.xii.2002. “ Biting collector on hand”. Coll. E. I. Schlinger (6 females; FBA 027949, BPBM) . Navai Village , alt. 700m. 6.vi.2003. “Moss on wet log”. Coll. E. I. Schlinger (2 females; FBA 027950, BPBM) . Koroyanitu Reserve , S17° 39’ E177° 32’, alt. 450m. 3.vi.2003, Coll. E. I. Schlinger (16 females; FBA 027951, BPBM) . Near Lautoka , Abaca Village, Vereni Creek Waterfall. S17.66866° E177.54200°, alt. 510m, 4.xii.2004. Coll. D. & R. Craig (larvae, pupae; DAC) . King’s Highway , Uru’s Waterfall, Waindaithi River. S17.66879° E177.54954°, alt. 120m, 5.xii.2004. Coll. D. & R. Craig (larvae, pupae; DAC) . Coral Coast , Queen’s Highway , Biasevu Village, Savunamatelaya Water Fall, S18.17973° E177.73834°, alt. 88–105m, 6.xii.2004. Coll. D. & R. Craig (larvae, pupae; DAC) . Near Lautoka , Abaca Village, Savuione Falls, S17.67429° E177.55430° (est.), alt. ca. 600m, 7.xii.2004. Coll. D. & R. Craig (larvae, pupae; DAC) .

Distribution FIJI: Kadavu, Ovalau, Taveuni, Vanu Levu, Viti Levu.

Comments

The taxonomic history of S. laciniatum has been confused ever since the name was proposed by Edwards (1924), in large part because original material from both Fiji and Vanuatu was mainly female adults, the morphological structures of which are highly conserved. It was not until larvae and pupae of the species were available from Fiji that Dumbleton (1973) recalled the name S. laciniatum from synonymy with S. jolyi . However, even then this action was contended by Crosskey (1974).

A certain degree of inter- or intra-island morphological divergence might be expected among Fijian simuliids given the diversity of running-water habitats and occurrence on five islands, albeit four of these are adjacent to each other. However, there is little evidence of such divergence. In comparison to material from the type locality area of S. laciniatum , (Mount Koroyanitu region — old Mount Evans, Lautoka, Viti Levu), adult females from Kadavu Island (the most remote) have a less hairy clypeus than do those from Viti Levu, and their legs are darker, although the colour pattern is the same. There are minor colour differences in adults from other islands, but colour is variable and appears in large part to depend on preservation. Pupae show no differences in gill arrangement ( Fig. 9h ) or granule pattern on the cuticle. Larvae from Kadavu have markedly more hypostomal setae (13 vs. 8 or 9) than those from elsewhere; however, they exhibit no other obvious differences. On balance we concluded that Fijian simuliids are exclusively S. laciniatum . Independent, preliminary COI mitochondrial DNA analysis also shows Fijian simuliids to consist of one species, with complete lack of clustering of variants, for either islands or habitats (A. Cywinska; unpublished data).

Larvae taken from trailing vegetation typically exhibit marked sexually dimorphic colour, i.e., females with evenly dark brown heads and grey bodies, and males with anterior head pale and body yellowish-orange. Larvae taken from rocky surfaces, and often in large numbers, tend not to show the colour patterns as above, but are rather intermediate in colour, i.e., grayish bodies, lighter head. The male: female ratio of all larvae sexed was normal.

Habitat preferences of larvae are rather varied. Localities where conditions appear to be favourable, such as the edges of waterfalls and large rocks with fast flow may yield no larvae or pupae at all. Rather, larvae in such circumstances are found exclusively on trailing roots or leaves. Other localities, however, have the reverse situation, with larvae exclusively on rock and commonly in large numbers. Some localities with fast flow and hard rock, but with no vegetation, lacked simuliids entirely. At a typical locality on Viti Levu, such as Vitongo Stream, inland from Lautoka at an altitude of 150 m, the velocity was 1.79 cm /s, water temperature 24.5 C, pH 8.5, and conductivity 90 µS. Larvae here were found in small numbers in full sunlight on rock. At Vereni Creek Cascade, altitude 510 m ( Fig. 24f ), adjacent to Abaca Village (Holotype region), the velocity was 0.7 m /s, water temperature 23.5 C, conductivity 50 µS and pH 8.1. Larvae here were found exclusively on vegetation. Details for other localities are given in Table 1 and other ecological details are dealt with under ‘Ecological Considerations’.

It is not clear if these marked differences in habitat preferences are determined by local ecological conditions, such as presence of other insects or petrolithic algae, or is an indication of genetic divergence between populations, but the DNA analysis indicates otherwise (A. Cywinska; unpublished data). Noticeable at the time of collection, however, was that simuliid larvae were not usually associated with other aquatic insects. The aquatic larvae of the pyralid moth Nymphula , often present in large numbers on hard substrates, are aggressive. It is not known if this Fijian Nymphula preys on simuliid larvae, but Gorayeb & Pinger (1978) reported that larvae of Simulium rorotaense (as S. fulivinotum ) are preyed on by South American Nymphula . Net-building caddisfly larvae ( Abacaria fijiana ), mayfly nymphs ( Cloeon , Pseudocloeon ), and chironomid larvae also are often abundant on rock habitats and are generally absent from vegetation, so perhaps there is competition for space on hard substrates.

There is one report of S. laciniatum larvae living phoreticaly on atyid shrimp in Ovalau ( Crosskey 1987). The phoretic behaviour of simuliid larvae is well documented elsewhere (Crosskey 1990).

Simulium laciniatum exhibits marked separation of cohorts. Collections of larvae on all islands normally consisted of a narrow range of instars. At Lambasa Waterfall, Kadavu, astronomical numbers of early instars (3rd or 4th) were found on leaves. Neither empty pupal exuviae nor flying adults were collected, both indicative of a prior generation. Physical data (Table 1) indicate that the stream is not unusual.

Although S. laciniatum is known now from five Fijian islands, we expect that it will occur on other high islands such as Gau, Koro, and Rabi, if suitable habitats of fastflowing water are present.

Simulium laciniatum can be acutely anthropophilic. Crosskey (1974) notes that, although the species has been considered a minor pest for many years, there are examples of it being a vicious biter. Ryan (2000) recounts one such example and gives the Fijian common name for simuliids as “navanava”. There is no record of ornithophily by females of S. laciniatum , nor for that matter, by any of the other species of Hebridosimulium , in agreement with the lack of a basal tooth on the pretarsal claws; a basal tooth typically indicates a history of blood feeding on birds ( Adler et al. 2004).

Figures

FIGURE 1. Typical examples of Hebridosimulium. a. Female Simulium callipygium (Santo). b. Head of male S. laciniatum (Fiji). c. Head of female S. pankumuense (Malekula). Scale bar = 0.5 mm.

FIGURE 4. Hebridosimulium. Female adult right pleural membranes. Dorsal to the left, anterior up. Scale bar = 0.1 mm.

FIGURE 5. Hebridosimulium. Female genitalia. a–d callipygium species group, e–j steatopygium species group. e. Adapted from Craig (1987). Scale bar = 0.1 mm. Abbreviations: an lb — anal lobe; cerc — cercus; gen fk — genital fork; hyp vlv — hypogynial valve; spmth — spermatheca.

FIGURE 6. Hebridosimulium. Male genitalia. a–b callipygium species group, c–f steatopygium species group. e. Paramere spines shown in detail. Scale bar = 0.1 mm. Abbreviations: adg mbm — aedeagal membrane; d plt — dorsal plate; goncx — gonocoxite; gonst — gonostyle; m scl — median sclerite; pm th — paramere teeth; v plt — ventral plate.

FIGURE 9. Pupal gill filaments of Hebridosimulium species. Scale bar = 0.2 mm.

FIGURE 11. Left lateral views of Hebridosimulium species larvae. Last-instar larvae, except l & n, which are penultimate. Arrowheads indicate dorsal tubercles. Scale bar = 1.0 mm.

FIGURE 13. Dorsal views of larval heads of Hebridosimulium species. a–e. callipygium species group, f–h. part of steatopygium species group. Last instars, except f & h, which are penultimate instars. Arrows (b & e) indicate anterior palatal bar. Scale bar = 0.2 mm.

FIGURE 15. Left lateral views of larval heads of Hebridosimulium species. Left labral fan removed for clarity. Last instars except c, which is penultimate. Scale bar = 0.2 mm.

FIGURE 16. Postgenal clefts and hypostoma of larvae of Hebridosimulium species. a–e callipygium species group, d–h steatopygium species group. Last instar, except b, which is penultimate. Scale bar = 0.1 mm.

FIGURE 18. Hypostomal teeth of larvae of Hebridosimulium species. Last instar. Scale bar = 0.05 mm.

FIGURE 20. Mandibular teeth of larvae of Hebridosimulium species. a–e callipygium species group, f–h steatopygium species group. Last instar, except b, which is penultimate. Arrow (e) indicates the blade region; asterisk the spinous teeth gap. Scale bar = 0.025 mm.

FIGURE 24. Habitats of larvae of Hebridosimulium species. a–e. Vanuatu.a. Santo, Adsone River. Type locality of S. adsonense. b. Santo, upper cascade, tributary of Sarakata River. Type locality of S. paradisium. c. Efate, Mele Cascade. Type locality of S. steatopygium. Note travertine terraces. d. South Pentecost, Warbot River. Type locality of S. supercilium. e. Santo, small stream, Millennium Cave region. Typical locality of S. subparadisium. f–i. Fiji. Habitats of S. laciniatum larvae. f. Viti Levu, Abaca Village, above Vereni Falls. Type region. g. Taveuni, Wairiki, Devo Peak, looking down water slide. h. Kadavu, Kadavacoro Village, Wailea Waterfall. i. Vanu Levu, Waisala Rain Forest Reserve, Ravini River.