Simulium (Hebridosimulium) johnfrumi Craig, 2006

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 : 30-39

Simulium (Hebridosimulium) johnfrumi Craig , n. sp.

( Figs. 4a , 5b , 6b , 8b , 9c , 11c , 13c , 15a , 16c , 18c , 20c )

Types

Holotype. Adult : double-pinned reared male, dried from alcohol. Label data—“ S. (H.) johnfrumi . VANUATU. Tanna. 2 nd strm, S of Bethel. 2m abs. 19.vi.1981, Coll. D. A. Craig ”, “ Holotype ” ( BM). Pupal exuviae and cocoon as subsidiary material . Paratypes. Adults: Nine double-pinned reared males, dried from alcohol. Two pinned, cleared and in glycerine vials. Label data—as for Holotype. Pupal exuviae and cocoon on points (4 BM, 3 BPBM, 2 DAC). One pinned female, cleared and in glycerine vial ( BM). Double-pinned reared female, dried from alcohol. Label data—as above, but with “ S19.58429° E169.31089°, alt. 24 m. 1.x.2004. Coll. D. A. & R. Craig ”. Right wing on slide ( DAC). Alcohol material. Label data—as for Holotype (larvae; BM, BPBM. larvae, pupae, reared males; DAC). Label data—“Vanuatu, Tanna, Louniel Village Casd, north of Point Lenamblain. S19.43082° E169.33971°, alt. 53m. 29.ix.2004. Coll. D. A. & R. Craig ” (larvae; DAC) .

Diagnosis

Relatively small species. Adults: thorax relatively light in colour. Female: palpal sensory vesicle markedly small; pleural membrane with sparse fine hairs; genital fork stem thickened, hypogynial valves markedly divergent, anal lobe small. Male: ventral plate keel large. Pupa: dense, small thoracic granules. Cocoon: slightly flared basally. Larva: head with distinct spot below stemmata; hypostomal median and lateral teeth distinct, paralateral teeth developed but small; fan rays ca. 37; abdomen callipygous, dorsolateral tubercles present.

Description Adult female (based on 2 reared specimens in alcohol). Body: head and abdomen very

dark blackish brown; thorax light brown; total length 2.2–2.4 mm. Head: width 0.80–0.83 mm; depth 0.51–0.57 mm; postocciput black, vestiture of dense short hairs; frons paler ventromedially; frons-head ratio (narrowest width of frons: greatest width of head) 1.0:4.2. Eye: interocular distance 0.19 mm; ommatidia 0.019 mm in diameter; 29 rows across, 35 rows down. Clypeus: 0.22 mm wide; concolourous with ventral region of frons; vestiture of black and pale hairs. Antenna: length 0.48–0.51 mm; flagellomeres grayish-yellow, scape and pedicel pale yellow. Mouthparts: 0.5 times length of head depth, substantial; mandible shorter than lacinia, poorly sclerotized with 23 fine inner teeth; lacinia with 9 inner teeth and 14 outer teeth; maxillary palpus, total length 0.55 mm; with all articles evenly brown, proportional length of 3rd, 4th, and 5th articles 1.0:0.9:1.4; sensory vesicle ovoid, less than 0.3 times width of 3rd article, opening 0.5 times width of vesicle. Thorax: length 1.1–1.2 mm; width 0.89–0.99 mm; postpronotal lobe paler than scutum; scutum evenly medium brown, vittae not distinct, vestiture of very sparse, fine pale hairs, with few longer darker hairs posteriorly; scutellum markedly pale, vestiture of few long black hairs and shorter pale hairs laterally, apical angle 120°, rounded; postnotum concolourous with scutum; pleural membrane ( Fig. 4a ), pale and with markedly fine pale hairs (barely observable at 50x in alcohol). Wing: length 2.2–2.3 mm; width 1.1 mm. Legs: overall appearance light brown and pale yellow; coxae light brown; femorae pale brown basally, yellow distally; tibiae yellow basally, brown distally; fore tibiae brown; mid tibiae yellow basally, brown distally; hind tibiae yellow. Abdomen: overall blackish brown; basal scale dark brown with fringe of long pale hairs; anterior tergites concolourous with scutum; tergite II 4 times wider than long, tergite III 2 times wider than long, both with vestiture of sparse fine pale hairs, tergites IV–VII and VII wider, with vestiture of longer fine pale hairs, tergite VIII paler. Sternum: paler anteriorly, concolourous with tergum posteriorly. Genitalia ( Fig. 5b ): sternite VIII pale, not deeply indented; hypogynial valves lightly pigmented with sparse vestiture; median edges concave and widely divergent, membranous apices directed medially, genital fork with stem short and substantial, posterolateral arms lightly pigmented, anterolateral extension rounded apically, small; anal lobes with anterolateral apodeme not markedly developed, median depression not strongly developed; cercus elongated.

Adult male (based on 5 reared specimens in alcohol). Body: overall dark brown to black; total length 2.4–2.6 mm. Head: width 0.85–0.92 mm; depth 0.58–0.63 mm. Eyes: upper ommatidia orange, 0.042 mm in diameter, ca. 15 across and 13 down; lower ommatidia dark brown, 0.018 mm in diameter, ca. 24 across and down. Clypeus: brown, paler medially; 0.2 times as wide as head; vestiture of long fine pale hairs. Antenna: total length 0.52 mm; pale yellow. Mouthparts: length 0.38 times head depth; mandibles insubstantial, finely tapered with apical hairs; lacinia broad basally, finely tapered apically with terminal hairs; maxillary palpus dark brown, 0.49 mm long, proportional lengths of 3rd, 4th, and 5th articles 1.0:0.9:1.7, third article darker and markedly hairy, sensory vesicle spherical, occupying 0.33 times width of article, opening 0.25 times width of vesicle. Thorax: length 1.0– 1.1 mm; width 0.8 mm; postpronotal lobes and scutum evenly light brown; scutum with 2 barely visible vittae; vestiture of even, small fine pale hairs; scutellum pale, apical angle 100°; vestiture of few black hairs laterally, remainder pale; postnotum concolourous with scutum, shiny: pleuron and pleural membrane concolourous with scutum; pleural membrane with hairs, but not visible at 50x in alcohol. Wing: 2.1–2.2 mm in length, 0.96–1.1 mm at maximum width. Legs: mainly yellowish; coxae and trochanters yellow; fore femur light brown, distal region of tibia and all of tarsus dark brown; mid leg as for foreleg; hind leg with femur pale and tibia hairy and pigmented distally, both swollen and flattened, width to length ca. 0.35, pretarsal claw with ca. 19 grappling hooks dorsally. Abdomen: dark brown; basal scale well developed and black, hairs markedly long, fine, and pale, extended to beyond 2nd segment; 1st and 2nd segment paler brown, remainder dark brown; vestiture of sparse pale hairs. Genitalia ( Fig. 6b ): gonocoxa 1.3 times longer than basal width, brown, with long black hairs on distal half; gonostyle paler, approximately 3.3 times longer than basal width, strengthening ridge not marked; ventral plate angulate laterally, proximal arms finely tapered, median keel subequal in length to remainder of plate, flattened apically; dorsal sclerite well developed and broadly V-shaped; median sclerite with stem 1.3 times as long as crosspiece length. Cerci: essentially absent.

Pupa (based on 10 specimens). Body length: female 2.3–3.0 mm, male 2.4–2.7 mm. Head and thoracic cuticle light brown, covered with dense small granules ( Fig. 8b ). Gill ( Fig. 9c ): 6 dorsal filaments subequal in length and shorter than remainder, occasionally dorsalmost filament markedly shorter; branching pattern (2+2)+2+2+2, often (2+2)+2+2+1+1; arising from short petioles; grayish brown, not markedly tapered; maximum length 1.4 mm. Cocoon: in females not completely covering pupa, in males occasionally extended part way along gills; anterior collar not well developed in Tanna specimens, well extended in those from Erromango; opening width less than basal width of cocoon; slightly flared basally.

Larva (based on numerous mature last-instar larvae). Body ( Fig. 11c ): total length 5.3–6.9 mm, females mottled dark grey, with paler intersegmental regions; males smaller, slightly more yellowish. Head ( Fig. 13c ): evenly light brown, slightly darker posteriorly; width 0.58–0.64 mm; length 0.70–0.83 mm; distance between antennal bases 0.35–0.40 mm; lateral margins of head subparallel (Tanna), more convex (Erromango); apotome pale anteriorly, darker posteriorly, ecdysial lines straight, diverging posteriorly, very broadly rounded at maximum width; anteromedial head spots slightly positive, posteromedial and posterolateral spots slightly negative; area surrounding stemmata pale with marked posterodorsal extension; distinct brown spot ventral to stemmata ( Fig. 15a ), less well developed in specimens from Erromango (such specimens with lateral head spots reminiscent of S. supercilium, Banks Islands ); posterior edge of apotome slightly emarginate; postocciput with fine medial extension to cervical sclerites (Tanna), or marginally so (Erromango). Antenna: total length 0.45 mm; distal article 0.3 times as long as basal articles, markedly longer than labral fan stalk; basal and distal article pale brown, median article pale. Labral fan: stalk light brown and clear; 36–38 fine rays, 0.70 mm in length, 8–10 rays less substantial; microtrichia markedly fine and elongate, 2 times longer than ray width, 4 or 5 finer microtrichia between thicker ones, pattern not distinct. Postgenal cleft ( Fig. 16c ): sharply V-shaped, 1.3 times deeper than wide; posteroventral elongate muscle scars light brown. Postgenal bridge: 0.3 times as long as cleft depth; genae evenly light brown. Hypostoma ( Fig. 18c ): ratio 4.8; overall cone-shaped; median tooth sharp, prominent, extended well beyond other teeth; lateral teeth deltoid; sublateral teeth small, medial teeth barely present; paralateral teeth absent; 3 or 4 markedly small lateral serrations; 8 or 9 hypostomal setae per side. Mandible ( Fig. 20c ): all apical teeth well developed; 5 or 6 clumped spinous teeth, small gap; serration and sensillum sharply cone-shaped, occasionally 2 sensilla, blade region smooth, essentially straight. Abdomen: thorax and anterior abdomen subequal in width, expanded evenly posteriorly to maximum width, callipygous, more so for Erromango material; dorsolateral tubercles present, increased in size posteriorly; pale posteroventrally with marked diagonal gray band, more so for Tanna material. Posterior circlet: directed posteriorly (Tanna) or more ventrally (Erromango); 154 rows of hooks; 24–28 hooks per row (total ca. 4,000).

Additional material examined

Tanna. Tannus (sic),?. x.1930, Coll. L. E. Cheesman (male, female; BM) . Lenakel , 0–150 m,?. iii.1970; 0–200 m,?. i.1973. Coll. N. H. L. Krause (2 females; BPBM) . Nr. Imalo , 22.ii.1985. Coll. B. S. Batson (larvae-in poor condition. DAC) . Louniel Village cascade. S19.43082° E169.33971°, alt. 53m. 29.ix.2004. Coll. D. A. & R. Craig. (larvae; DAC) . Stream south of Bethel. S19.58429° E169.31089°, alt. 24 m. 1.x.2004. Coll. D. A. & R. Craig (larvae; DAC) . Erromango. ?. viii.1930. Coll. L. E. Cheesman (4 females; BM) . 8–11 km W of Ipota , 100– 200 m.?. iii.1970. Coll. N. H. L. Krause (8 females- 2 in vials; BPBM) . Dillons Bay , Williams River, main channel. S18.82137° E169.03061°, alt. 25m. 26.ix.2004. Coll. D. A. & R. Craig (larvae, pupae, reared adults; DAC, BPBM) . Williams River , right channel. S18.82596° E169.004445°, alt. 47m. 27.ix.2004. Coll. D. A. & R. Craig (larvae; DAC) .

Etymology

Named after John Frum, of dubious existence, but integral to the so-called ‘cargo cults’ on Tanna.

Distribution VANUATU: Tanna, Erromango.

Comments

This species is closely related to S. tuberculum in Efate. Larvae of both species possess dorsolateral tubercles, a callipygous abdomen and generally ventrally directed posterior circlet, but they differ in larval head-spot pattern and armature on the dorsum of the pupa. Adults of S. johnfrumi are slightly smaller and more yellow than those of S. lucyae (Aneityum) . While females have substantial mouthparts, the mandible is not highly sclerotized. Whether they bite, as do females of S. lucyae , is moot. Certainly, there are no records of simuliids biting humans on either Tanna or Erromango. Streams and rivers in Tanna and Erromango are not travertine as are those of the more northern islands. At the type locality, a typical Tanna stream ( Fig. 23e ), larvae and pupae of S. johnfrumi were taken from small basalt rocks and leaves in moderate velocity (ca. 80 cm /s). At the Louniel Village cascade, larvae and the pupa were found exclusively on trailing vegetation and leaves in fast velocity (1.5 m /s). There are differences in the abdomen of larvae of S. johnfrumi ; they are less callipygous in populations from Tanna than those from Erromango. Similarly, there are differences in larval head-spot pattern. The pupae and adult male genitalia are, however, identical. Further analysis may show the Tanna and the Erromango material to be separate species, but they will be closely related.

Figures

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 8. Hebridosimulium. Pupal thoracic cuticle. Scale bar = 0.1 mm.

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 23. Habitats of larvae of Hebridosimulium species, Vanuatu. a. Santo, Sarakata River, UNELCO Hydro Station. Type locality of S. callipygium. Note limestone substrate. b. Santo, Upper Sarakata River, Millennium Cave region. Typical habitat of S. callipygium and S. subparadisium. c. Malekula, Wesso River, downstream of cascade. Type locality of S. spiroi. Note travertine substrate. d. Banks Islands, Vanua Lava, Tahiti River. Type locality of S. banksi and S. undulatum. e. Tanna, stream south of Bethel. Type locality of S. johnfrumi. f. Malekula, Pankumu River. Type locality of S. pankumuense. g. Efate, Ewor River, La Cressionnière. Type locality of S. tuberculum. Note the travertine terraces.