Simulium (Hebridosimulium) jolyi Roubaud., 1906

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 : 50-53

Simulium (Hebridosimulium) jolyi Roubaud.

( Figs. 5f , 9g , 13f , 16f , 18f , 20f )

Simulium jolyi: Roubaud 1906: 142

S. (Hebridosimulium) jolyi: Crosskey (1967: 27) ; Crosskey (1974: 150); Crosskey & Howard (2004: 29) in part not Roubaud 1906.

Types

Holotype. Adult: female on standard pin (dried from alcohol and glycerine). Label data – “TYPE (red, printed), Museum-Paris. Nouv.- Hébrides. Dr. Joly 1903”. Condition excellent. Left hind tarsus missing . Paratypes. Adults: four females double pinned (dried from alcohol). Three with label data – “Museum-Paris. Nouv.- Hébrides. Dr. Joly 1903”, (two re-pinned with cleared, stained genitalia in glycerin vials on the pin), one with label data- “Museum Paris. Nouv.- Hébrides. Ile Mallicolo. Port Sandwich. Dr. Joly 1903”, “Museum Paris (printed). N elles Hébrides. Port Sandwich, Dr. Joly 1903. Simulium jolyi Roub. Avril 1903 (pencil)” .

Diagnosis

Female: lighter in colour than S. laciniatum and S lucyae ; genital fork stem long and thin, hypogynial valves flexed laterally, spermatheca large and darkly pigmented. Pupa: 10 gill filaments, petioles moderately elongate, filament branching pattern ((2+2)+2)+2+1+1, thoracic cuticle with sparse granules; anterior collar of cocoon well developed. Larva: median hypostomal tooth extended beyond lateral teeth; posterior abdomen steatopygous; posterior circlet of ca. 7,200 hooks.

Description

Adult female (based on type material). Body: head and abdomen very dark brown, thorax light brown; length 2.0– 3.6 mm. Head: width 0.71–0.93 mm; depth 0.47–0.67 mm; postocciput very dark brown, vestiture of sparse, silvery, small hairs; frons lighter; fronshead ratio (narrowest width of frons: greatest width of head) 1.0:4.0. Eye: interocular distance 0.2 mm; ommatidia 0.019 mm in diameter; 45 rows across and 42 down at mideye. Clypeus: 0.25 mm wide; concolourous with frons; vestiture of dense black and pale hairs. Antenna: length 0.46–0.54 mm; flagellomeres pale yellow; scape, pedicel, and first flagellomere slightly darker than remainder. Mouthparts: 0.40 length of head depth; mandible well developed with 15 inner teeth decreased in size proximally; lacinia with 10 inner teeth and 16 outer teeth; maxillary palpus evenly dark brown, proportional length of 3rd, 4th, and 5th articles 1.0:0.8:1.4; sensory vesicle spherical, ca. 0.3 times width of 3rd article, opening 0.8 times width of vesicle. Thorax: length 0.99–1.22 mm; width 0.85–0.96 mm; postpronotal lobes concolourous with scutum (Malekula); scutum evenly medium brown, vittae not distinct, vestiture of sparse, very fine pale hairs; scutellum pale, vestiture of stiff long black hairs and pale hairs laterally, apical angle 90°, very sparse black hairs; postnotum concolourous with scutum; pleural membrane pale and with very small hairs. Wing: length 1.7–2.8 mm; maximum width 0.96–1.2 mm. Legs: fore leg, coxa, trochanter, and femur dark brown, basal tibia yellow, remainder dark; mid leg, coxa, trochanter, and basal femur yellow, distal femur black, basal tibia yellow, remainder black; hind leg as for mid leg except tarsus yellow with calcipala and remainder black; some specimens with legs darker overall. Abdomen: overall blackish brown; basal scale brownish black, with fringe of long pale hairs; vestiture of evenly distributed short dark hairs. Genitalia ( Figs 5f ): sternite VIII deeply indented, broader anteriorly, median region pale; hypogynial valves lightly pigmented with sparse vestiture; median edges slightly concave, diverged, more so posteriorly, apical membranous extension broadly rounded and insubstantial, directed medially; genital fork stem narrow, lateral arms lightly pigmented, anteriorly directed apodeme well developed and rounded; anal lobes with anterolateral apodeme and anteromedian concavity not markedly developed; cercus not markedly developed.

Adult male. Unknown.

Pupa (based on pharate specimens). Gill ( Figs. 9g ): maximum length 1.4–1.5 mm; petioles moderately elongate, branching pattern variable, e.g., ((2+2)+2)+2+2 or ((2+2)+2)+2+1+1; dorsal filaments shorter, but not markedly more so than others, fine, similar in thickness; light grey.

Larva (based on numerous last-instar larvae (previously dried) and a few fresher penultimate instars). Body (not illustrated): total length 5.5–6.7 mm; probable females mottled dark grey, with paler intersegmental regions, probable males pale yellow. Head ( Fig. 13f ): evenly medium brown, some evenly pale yellow; width 0.58–0.78 mm; length 0.74–1.0 mm; lateral margins of head subparallel to slightly convex; frontoclypeal apotome pale anteriorly, darker posteriorly; ecdysial lines straight, diverged posteriorly, maximum width at posterior; anteromedian head spots slightly positive to give Eiffel Tower configuration. Antenna: total length 0.49 mm; distal article 0.28 times as long as basal articles, 0.5 length of distal article extended beyond labral fan stalk; evenly very pale yellowish brown. Labral fan: stalk markedly clear, neither posterobasal notch nor anterior palatal bar markedly developed; 40–42 fine rays, 0.75–0.81 mm in length, 10–14 rays less substantial, 2 or 3 very fine; microtrichia markedly fine and elongate, 2 time longer than ray width, indistinct pattern of 4 or 5 small microtrichia between those longer. Postgenal cleft ( Fig. 16f ): deeply arrowhead-shaped, slightly concave edges; 1.5 times as long as maximum width. Postgenal bridge: 0.4 times as long as cleft depth; genae more or less evenly lightly pigmented, posterolateral elongated muscle scars neutral to negative. Hypostoma ( Fig. 18f ): overall cone-shaped; ratio 5.0; median tooth markedly prominent; adjacent sublateral teeth larger than others and elevated on median tooth base, other sublateral teeth depressed, lateral teeth sharp, slightly scalloped medially and directed laterally; paralateral teeth very poorly developed, essentially absent, 3 or 4 very small irregular lateral serrations; 11 or 12 substantial hypostomal setae per side. Mandible ( Fig. 20f ): preapical and subapical teeth well developed; apical tooth prominent; 5 or 6 clumped spinous teeth, spinous teeth gap absent; serration and sensillum with distinct concave sides and unusual domed anterior base; blade region evenly convex. Abdomen: thorax and anterior abdomen subequal in diameter, steatopygous posteriorly but not markedly so; dorsal tubercles absent. Anal sclerite: anterodorsal arms subequal in length to posterolateral arms, splayed at apices and paler; medial strut extended; posterolateral arms tapered evenly to 0.4 times distance around circlet of hooks. Posterior circlet: apparently

directed more posteriorly; 206–210 rows of hooks; 33–37 hooks per row (total ca. 7,200).

Additional material examined

Malekula. Nr. Port Stanley , alt. 10 & 200 ft. 1–4.x.1971. Coll. J. Smart (2 tubes larvae, pupae in alcohol — previously dried; BM). Pankumu River, S16.27629º E 167.63687º, alt. 15m. 2.ix.2004. Coll. D. A. & R. Craig (penultimate instar larvae; DAC) .

Distribution VANUATU: Malekula.

Comments

As noted above, Roubaud (1906) did not designate a Holotype. The specimen with the “TYPE” label is, however, accepted here as such.

Assigning material to S. jolyi has been difficult. Although the five female types are in good physical shape, albeit over 100 years old, the colours are muted in tone, in large part probably because the specimens were originally in an alcohol-glycerine mixture. Further, genitalic and other characters of female Hebridosimulium are conservative and of not great use in diagnosing species. Adult material from Malekula, mainly collected by Cheesman in the 1930s and with better colour preservation is not placed in S. jolyi , because recent material of immatures from Malekula shows at least three species of Hebridosimulium on that island, with no clear indication of which is S. jolyi . Two of these species are designated as S. pankumuense and S. spiroi (see later), both larvae of which are clearly specialized for the hydraulic conditions of large rivers and cascades. The validity of these two species were subsequently confirmed by mitochondrial CO1 DNA analysis (A. Cywinska, unpublished data). A third entity is of earlier collected larvae and pupae taken by the Royal Society-Percy Sladen Expedition to Vanuatu in 1971 ( Corner and Lee 1975) from streams near Port Stanley, east central Malekula, and deposited in the BM. That material had been allowed to dry and is in no condition for DNA analysis and is barely useable for morphological examination. Further, no new material of any stage of S. jolyi has been taken from the type locality, Port Sandwich, Malekula, where maps show two small streams flowing into the harbour. An assumption is made here that S. jolyi larvae inhabit such streams. Accordingly, the 1971 immatures taken by the Royal Society are assigned to S. jolyi . A small number of immature larvae from the Pankumu River, Malekula, that lack dorsal tubercles are also assigned to S. jolyi . This is an unsatisfactory situation that will require further detailed collection of material from Malekula.

Figures

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