Simulium (Hebridosimulium) adsonense Craig &amp; Currie &amp; Hunter &amp; Spironello 2006, n. sp.
Creators: name: Craig, Douglas A.
name: Currie, Douglas C.
name: Hunter, Fiona F.
name: Spironello, Mike
Publisher: name: Zenodo
Year: 2006
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Simuliidae
Simulium
Simulium adsonense

description: <i>Simulium</i> (<i>Hebridosimulium</i>) <i>adsonense</i> Craig n. sp. (Figs. 5j, 8f, 10e, 11m, 14e, 17e, 19e, 21e) <i>Types</i> <b>Holotype</b>. Adult: female, double pinned. Label data – " <i>Simulium</i> (<i>Hebridosimulium</i>) <i>adsonense</i> <i>.</i> VANUATU, Santo, Adsone River, S15.55968° E166.96876°, alt. 59m, 15.ix.2004. Coll. D. A. &amp; R. Craig. HOLOTYPE, #16572" (BPBM). Genitalia in glycerine vial. Pupal cocoon and exuviae as subsidiary material on point; right gill missing. <b>Paratypes</b>. Alcohol material: Pupae: exuviae (BPBM, DAC). Larvae: later instars (BPBM, DAC, LCNZ, ROM). Label data as for Holotype, but with " PARATYPE ". <i>Diagnosis</i> Relatively large species. Adults: black; pleural membrane with distinct yellow hairs; legs markedly bicolourous. Pupa: cuticle medium brown with coarse granules, gill petioles essentially absent, filaments tapered markedly. Larva: head dark brown, anterior cephalic apotome medium brown; hypostomal teeth distinct; abdomen only slightly steatopygous; abdominal dorsolateral tubercles absent. <i>Description</i> <b>Adult female</b> (based on 1 reared specimen). Body: head, thorax and abdomen blackish brown; total length 2.6 mm. Head: width 0.85 mm; depth 0.55 mm; postocciput, vertex and frons black, vestiture of sparse, erect, black hairs; frons-head ratio (narrowest width of frons: greatest width of head) 1.0:3.4. Eye: interocular distance 0.16 mm; ommatidia 0.015 mm in diameter; ca 35 rows across and down at mid-eye. Clypeus: 0.24mm wide, concolourous with frons. Antenna: length 0.47 mm; flagellomeres blackish brown, scape and pedicel pale. Mouthparts: 0.4 length of head depth; mandible with ca. 28 fine inner teeth; lacinia with 17 inner teeth and 12 outer teeth; maxillary palpus with total length 0.45 mm, all articles evenly dark brown, proportional length of 3rd, 4th, and 5th articles 1.0:0.8:1.5; sensory vesicle elongate, ca. 0.3 times width of 3rd article, opening 0.8 times as wide as vesicle. Thorax: length 1.3 mm; width 1.1 mm; postpronotal lobes slightly paler than scutum; scutum evenly very dark brownish black, vestiture of sparse silver hairs; 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. Wing: length 2.7 mm; width 1.1 mm. Legs: coxae pale brown; fore leg, femur brown, tibia pale proximally, remainder of leg black; mid leg femur brown medially, tibia pale proximally, remainder of leg black; hind leg as for mid leg. Abdomen: anterior light gray, remainder brownish black; vestiture of dense silver hairs, long laterally, with few black hairs; basal scale of golden hairs. Genitalia (Fig 5j): median region of sternite VIII moderately depressed and pale posteromedially; hypogynial valves with vestiture of sparse short hairs; medial edges essentially parallel, posterolateral edges concave, membranous apical extensions rounded and simple; genital fork with stem long and markedly narrow, posterolateral arms with medial constriction, anteriorly directed apodeme rounded; anal lobes rounded with sparse longer hairs posteriorly, anterior anterolateral apodeme not well developed, anteromedian concavity distinct with sparse hairs; cercus narrow; spermatheca ovoid, moderately pigmented. <b>Adult male.</b> Unknown. <b>Pupa</b> (based on 4 specimens). Body length: 3.0 mm. Gill (Fig. 10e): maximum length of female 1.2–1.5 mm, male 1.1 mm; petioles short, branching pattern (2+2)+2+2+2, light brown, thickest proximally, tapered rapidly. Head and anterior thorax with evenly distributed sparse, dark brown, large, irregular granules, cuticle medium brown (Fig. 8f). Cocoon: markedly boot shaped, base not flared laterally, anterior collar well raised above substrate; length of female 3.8–3.9 mm long, 1.5–1.7 mm wide; male 2.8–3.0 mm long, 1.4–1.8 mm wide. <b>Larva</b> (based on 3 mature last-instar larvae). Body (Fig. 11m): relatively large; total length 6.9–7.1 mm: females overall grey, males with orange tinge, thorax evenly pigmented, anterior abdominal segments pigmented with intersegmental areas pale, producing banded appearance, posterior abdominal segments evenly pigmented. Head (Fig. 14e): both sexes with dark brown pigmentation, lighter anteriorly on frontoclypeal apotome, more so in males; fan stems light brown, triangular region anterior and basal on stem markedly pale, as is region medial of antennal bases and sockets of trichoid sensilla pair 5 and 6, medial of antennal base; head-spot pattern negative, but indistinct; ecdysial lines pale and straight, diverging; width 0.65 mm, length 0.71 mm; distance between antennal bases 0.36 mm; lateral margins of head evenly convex; posterior edge of apotome not emarginate; postocciput finely extended between cervical sclerites and apotome. Antenna: total length 0.83 mm; distal article 0.33 times as long as basal articles, extended barely beyond labral fan stalk, distal article medium brown, distal portion of basal article concolourous, remainder paler. Labral fan: stalk medium brown, anterior palatal bar markedly protruded anteromedially; 37–45 rays, 0.70 mm in length, 10–12 rays less substantial; microtrichia 0.5 times length of ray width, pattern indistinct. Postgenal cleft (Fig. 17e): markedly arrowhead shaped, slightly deeper than wide with convex edges; posteroventral elongated muscle spots neutral. Postgenal bridge: 0.6 times as long as cleft depth; genae and postgenae dark brown. Hypostoma (Fig. 19e): overall cone-shaped; ratio 5.1; median tooth prominent, lateral teeth smaller and scalloped medially, splayed laterally; sublateral teeth small, well spaced and equal in size; paralateral teeth not obvious; lateral serrations absent; 9–11 substantial hypostomal setae per side. Two substantial hairs situated medially. Mandible (Fig. 21e): apical tooth markedly developed; 4–6 spinous teeth, largely covered by subapical teeth; spinous teeth gap small; serration and sensillum distinct; blade region smooth, barely convex. Abdomen: anterior abdomen subequal in width to thorax, expanded gradually posteriorly to 5th abdominal segment then slightly steatopygous. Posterior circlet: directed posteriorly; 175–180 rows of hooks; 29–31 hooks per row (total ca. 5,300). <i>Additional material examined</i> <b>Santo</b>, Adsone River, S15.55968° E166.96876°, alt. 59 m, 15.ix.2004. Coll. D. A. &amp; R. Craig. (immature larvae; DAC). <i>Etymology</i> Named after the type locality river, but based on an older spelling, Adson, rather than the modern spelling, Adsone. <i>Distribution</i> VANUATU: Santo, Adsone River. <i>Comments</i> <i>Simulium adsonense</i> is found in Santo only, along with small numbers of <i>S. steatopygium</i> larvae. Association of larvae and pupae of <i>S. adsonense</i> was confirmed by comparison of pupal cuticle (Fig. 8f) and gills (Fig. 10e) of pharate pupae in the mature last-instar larvae, to the mature pupae. The type locality (Fig. 24a) is shallow, with very fast water (respectively ca. 5 cm and 1.8 m /s) on an old concrete causeway. Larvae and pupae were also recovered from a riffle upstream. Larvae exhibit behaviours similar to those of <i>Inseliellum</i> in Polynesia that are adapted to shallow fast water (Craig 1997), namely, even spacing of larvae and lack of body twisting, so that the ventral surface of the labral fans are directed towards the substrate. The latter behaviour is similar to that observed for larvae of <i>S. paradisium</i>. The number of hooks on the posterior circlet is also higher, again in keeping with adaptation to high-velocity habitats. With the larva not markedly steatopygous and the pupal cuticle unique, placement of <i>S. adsonense</i> in the <i>steatopygium</i> species group was based solely on the genitalia of the single female adult. The relationship of this species may have to be reconsidered once additional material comes to hand.
description: Published as part of <i>Craig, Douglas A., Currie, Douglas C., Hunter, Fiona F. &amp; Spironello, Mike, 2006, A taxonomic revision of the southwestern Pacific subgenus Hebridosimulium (Diptera: Simuliidae: Simulium), pp. 1-90 in Zootaxa 1380 (1)</i> on pages 76-78, DOI: 10.11646/zootaxa.1380.1.1, http://zenodo.org/record/5071393
description: {"references": ["Craig, D. A. (1997) A taxonomic revision of the Pacific black fly subgenus Inseliellum (Diptera: Simuliidae). Canadian Journal of Zoology, 75, 855 - 904."]}