Paraustrosimulium obcidens Craig, Moulton & Currie

Craig, Douglas A., Moulton, John K. & Currie, Douglas C., 2017, Taxonomic revision of Paraustrosimulium Wygodzinsky & Coscarón: reassignment of Austrosimulium colboi and description of P. obcidens n. sp. from Western Australia, Zootaxa 4337 (4), pp. 451-492: 464-475

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Paraustrosimulium obcidens Craig, Moulton & Currie

new species

Paraustrosimulium obcidens Craig, Moulton & Currie  , new species.

(Figs. 43–85)

Description. Adult female (based on reared specimens). Body (Fig. 43): general body colour evenly dark brown, specimens from Styx River (Fig. 43) darker than from Deeside Coast ( Fig. 45View FIGURES 45 – 50); total length 1.6–2.3 mm. Head ( Fig. 46View FIGURES 45 – 50): width 0.54–0.60 mm; depth 0.35 mm; postocciput black with coarse hairs; frons blackish brown; frons–head ratio (narrowest width of frons: greatest width of head) 1.0:7.5. Eyes: dark red, interocular distance 0.06 mm; ommatidia 0.014 mm in diameter; 35–39 rows up and across at mid–eye. Clypeus: blackish brown; 0.15mm wide; vestiture of sparse pale hairs. Antenna ( Fig. 47View FIGURES 45 – 50): pedicel small, scape larger, both yellowish, first flagellomere yellowish basally, other flagellomeres black, subequal in size, apical flagellomere markedly elongate; total length 0.5 mm, markedly extended beyond head margin. Mouthparts: ca. 0.5 length of head depth; maxillary palpus ( Fig. 48View FIGURES 45 – 50), total length 0.32–0.35 mm, 1 st and  2nd articles pale, 3rd article semispherical and dark brown, sensory vesicle ovoid, 0.5x length and width of 3rd article, opening 0.25x width of vesicle; 4th article short, 0.5 x 5th article length; proportional length of 3rd, 4th and 5th articles 1.0:0.5:1.0; mandible ( Fig. 49View FIGURES 45 – 50), slightly expanded apically, sharply pointed with 7–9 irregularly arrayed, finely pointed outer teeth, 20–23 fine, small inner teeth apically, ca. 9 other poorly expressed teeth proximally; lacinia markedly with 12 or 13 inner and outer teeth; cibarial cornuae splayed, lacking apical fluting or sculpture, pigmented terminated, central depression shallow and broad ( Fig. 50View FIGURES 45 – 50); cervical sclerites markedly developed ( Fig. 45View FIGURES 45 – 50). Thorax: length 0.80–0.83 mm; scutum not markedly domed (Fig. 43, 45), evenly blackish brown, vestiture of evenly distributed recumbent silver hairs; postpronotal lobe with longer hairs; antepronotal lobe with longer hairs; scutellum and postnotum concolourous with scutum; scutellar depression and scutellum with distinct long substantial black hairs; pleuron and anepisternal membrane blackish brown, bare; katepisternal sulcus distinct. Wing ( Fig. 51View FIGURES 51 – 55): length 2.1–2.4 mm; width 1.1–1.2 mm; veins not markedly pigmented; a:b ratio 1.0:3.2, otherwise as for P. colboi  . Haltere: stem pale, knob dark. Metathoracic furcasternum ( Fig 52View FIGURES 51 – 55): projections larger. Legs: overall yellowish; foreleg with coxa to tibia yellow then darker. mid leg slightly darker yellow, hind leg similar; hind basitarsus ca. 5.5x as long as its greatest breadth, ventral row of stout spines absent; calcipala well developed, 0.6x width of basitarsus, pedisulcus distinct ( Fig. 53View FIGURES 51 – 55); tarsal claw with well developed tooth and basal heel, separated by distinct notch ( Fig. 54View FIGURES 51 – 55). Abdomen ( Fig. 55View FIGURES 51 – 55): slightly darker brown than thorax; abdominal scale darker, hairs not greatly extended; tergite II 3x wider than long, broadly V–shaped, other tergites not expressed; dorsal vestiture of small black hairs increased in density posteriorly. Genitalia: sternite VIII vestiture of sparse coarse dark hairs posterolaterally; hypogynial valves ( Fig. 56View FIGURES 56 – 59) triangular, lightly pigmented with vestiture of sparse short hairs and triads of microtrichia; median edges slightly sinuous, strengthened along edge, divergent; genital fork ( Fig. 57View FIGURES 56 – 59) with anterior arm short and broad, slightly sclerotized and pigmented narrowly medially, expanded and round anteriorly, lateral arms broad, indications of lateral apodeme (as in Gigantodax  ), more distal apodeme (as in Austrosimulium  ) present only as ridge, lateral plates large, angular posteromedially, rounded posterolaterally; spermatheca ( Fig. 58View FIGURES 56 – 59) elongated ovoid, surface smooth; sparse internal acanthae; spermathecal duct pigmented well down duct, sculpting at junction absent; cercus ( Fig. 59View FIGURES 56 – 59) as wide as long, broadly rounded in lateral view, anal lobe small, angulate proximally.

Adult male (based on 4 reared specimens). Body (Fig. 60): general colour blackish brown, relatively long legs; total length 1.5–2.0 mm. Head (Fig. 61): width 0.55–0.60 mm; depth 0.45 mm. Eyes: upper ommatidia blackish red, 0.03 mm in diameter, ca. 12 across and down; lower ommatidia almost black, 0.013 mm in diameter, ca. 20 across and down. Clypeus: black; 0.13 mm wide; vestiture of very sparse black hairs. Antenna ( Fig. 62View FIGURES 62 – 67): total length 0.51–0.55 mm; scape and pedicel concolourous, pedicel lighter apically, first flagellomere lighter basally, otherwise concolourous; first flagellomere longer than wide, others subrectangular, becoming bead–like distally; non–tapered, distal flagellomere markedly wider than others; flagellum hirsute. Mouthparts: poorly developed; length 0.28x head depth; mandibles insubstantial, finely tapered with apical hairs; laciniae finely tapered apically with a few terminal hairs; maxillary palpus not markedly pigmented, 0.38 mm long, articles subequal in diameter; 3rd article slightly darker; proportional lengths of 3rd, 4th and 5th articles 1.0:0.9:1.6, sensory vesicle small, occupying 0.5x width of article, opening 0.75x width of vesicle. Lateral cervicales well developed (Fig. 60). Thorax: length 0.54–0.6 mm; in alcohol, scutum evenly velvety black, dry more yellow; vestiture of fine recumbent pale hairs; scutellum and postscutellum concolourous with scutum, coarse long black hairs. Metathoracic furcasternum ( Fig. 63View FIGURES 62 – 67): with small projections. Wing: 1.9 mm in length, 0.9 mm in width; otherwise as for female. Haltere: tan. Legs: blackish brown; hind tibia slightly expanded medially; basitarsus about 6.4x as long as its greatest breadth, lacking row of stout spines; calcipala as for female; tarsal claw partially covered by grappling pad of ca. 20 hooks. Abdomen ( Fig. 64View FIGURES 62 – 67): black; abdominal scale with long fine hairs, tergites not broad, increasing in size posteriorly, not markedly hirsute. Genitalia: in ventral view ( Fig. 65View FIGURES 62 – 67); ventral plate directed ventrally giving appearance of flat apex, 1.8–2.0x wider than long ( Fig. 66View FIGURES 62 – 67), curved giving appearance of a keel, roughly sculpted laterally at attachment of arms, vestiture of fine hairs, anteromedial depression shallowly U– shaped, proximal arms fine in ventral view, heavily pigmented apically, subequal in length to ventral plate, basal arms short and unpigmented; median sclerite well expressed, divided apically (M–shaped); parameres plate–like, but not markedly developed, strengthened laterally, apically with ca. 12 fine spicules, with ca. 5 larger spines meeting those from the other side; adeagal membrane densely covered with minute microtrichia; gonocoxa 2.5x longer than median width, coarse hairs on distal 2/3; gonostylus approximately 2.5x longer than basal width, angulate, apically with 2 or 3 substantial terminal spines, variable ( Fig. 67View FIGURES 62 – 67).

Pupa (based on numbers of specimens) ( Fig. 68View FIGURES 68 – 73). Body: length, 1.8–2.5 mm. Head ( Fig. 72View FIGURES 68 – 73): frontal cephalic plate lacking dorsal depression; ratio of basal width to vertex width of female 1.0:1.5, for basal width to length 1.0:1.5, broadly rounded apically, male ratios similar; evenly covered with low clear tubercules, muscle scars distinct, frontal and facial setae present, insubstantial, ocular spine absent. Thorax: cuticle light brown to clear; dorsum covered evenly with small tubercles, no pattern ( Fig. 69View FIGURES 68 – 73); dorsocentral setae spine–like, on raised bases, markedly black, slightly curled tips. Gill ( Fig. 70View FIGURES 68 – 73): essentially as for P. colboi  , 0.9 – 1.3 mm full length with ca. 16– 18 wrinkled annulations; stub–like posterior lobe absent; surface structure of annulations and regular trabeculae ( Fig. 71View FIGURES 68 – 73). Abdominal armature: segment I and II lightly pigmented brown, tergite I with anteriorly directed substantial setae, II similar; III slightly tuberculated anteriorly, four hooks posterad, one small hook laterally; IV similar with slight pigmentation, two small hooks laterally; V with poorly expressed spine comb anterad, four fine setae posteriorly, two sternal hooks close together medially; VI as for tergite V, two sternal hooks wide apart; VII as for tergite VI, four sternal hooks; VIII spine comb present, but poorly expressed, four fine setae posteriorly, sternum with lightly expressed bed of scales; IX spine comb barely present, terminal spines markedly short and blunt, grapnel hooks exacerbated and pigmented ( Fig. 73View FIGURES 68 – 73). Cocoon ( Fig. 68View FIGURES 68 – 73). Essentially as for P. colboi  , but not closely fitted to pupa; ventral floor absent; incorporated extraneous material rare.

Larva (based on two last instar larvae). Body ( Fig. 74View FIGURES 74 – 79): overall brownish, stubby (head large in relation to body), thorax and anterior abdomen subequal in diameter, expanded smoothly posteriorly; total length 4.2–4.9 mm. Head ( Figs. 75View FIGURES 74 – 79): distinctly pale translucent yellowish brown, head spots poorly expressed, anteromedial spots not evident, posteromedial spots form distinct U–shape, mediolateral spots small and distinct; faint pigmentation along posterior of apotome; head length 0.60–0.70 mm, width 0.40– 0.43 mm; distance between antennal bases 0.25– 0.27 mm; mandibular and antennal phragma lightly expressed; lateral margins of head subparallel, smoothly convex posteriorly; cervical sclerites small, distinct, not fused to postocciput; anterolateral edges of apotome sharply pigmented; genae lacking marked 'eye brow' over stemmata; ecdysial suture expanded posteriorly to behind stemmata then curved medially. Antenna ( Fig. 76View FIGURES 74 – 79): overall clear pale brown; total length ca. 0.45 mm, extended well beyond fan stem, distal article longer than other two combined, proportions of basal, median and distal articles 1.0: 0.4: 1.7. Labral fan: stem light brown, darker along posterior edge; ca. 55 markedly fine rays, 0.60 mm in length, 0.01 mm in width; distinct pattern of microtrichia with longer one subequal to ray width, interspersed with ca. 5 shorter decreased rapidly in length. Mandible ( Figs. 77, 78View FIGURES 74 – 79): apical brush well expressed: apical teeth finely expressed on narrow extension; apical tooth distinct, 11 fine spinous teeth; mandibular serrations separate and distinct, sensillum expressed as fine hair; blade region long, smooth and flat. Maxilla ( Fig. 79View FIGURES 74 – 79): lobe cone–shaped, asymmetrical, palp longer than lobe, slightly separated, 2.6x as long as basal width. Postgenal cleft ( Fig. 80View FIGURES 80 – 84): well expressed, U–shaped with sclerotized posterior tentorial pit cuticle, pits ovoid; ratio of hypostoma, bridge and cleft 1.0:1.6:1.0; suboesophageal ganglion not pigmented. Postgenal bridge: pale and concolourous with genae. Hypostoma ( Fig. 81View FIGURES 80 – 84): ventral edge narrowly domed–shaped; 13 teeth, median tooth barely protruded beyond edge, two sublateral teeth smaller and subequal in length, other tooth larger, but only just protruded beyond edge, lateral teeth larger and slightly protruded, paralateral teeth smaller and sharp, variable expression, no others evident; no hypostomal serrations; four hypostomal setae per side. Thorax: pale; pharate pupal gill as black, paddle–shaped horn; annulations of gill concertinaed with annulations pleated and folded ( Fig. 82View FIGURES 80 – 84). Abdomen: medium brown, lighter posteriorly; abdominal segments expanded smoothly; posteroventral tubercles not markedly developed. Anal papillae: three simple lobes. Posterior proleg ( Fig. 83View FIGURES 80 – 84): rectal scales absent; anal sclerite X–shaped with medial region poorly expressed, anterior arms not flared, subequal in length to posterior arms, interarm struts distinct, posterior arms finely expressed; accessory sclerite absent, pigmented semicircular sclerite absent, but clear cuticle evident in that position. Posterior circlet: ca. 93 rows of 11–13 hooks (total ca. 1,100).

Etymology. From Latin obcidens  [in reference to the 'west' and 'setting sun'].

Types. Holotype (Fig. 43): micro–pinned reared female (dried with Pelldri II™) with pupal exuviae as subsidiary material in microvial. Label data (Fig. 44): [ Holo/ type (red)] [ Paraustrosimulium  / obcidens  ] [Western Australia / Styx River, S34.8845° / E117.1045°, alt. 50 m./ 9–xi–2014, Coll. J.K./ Moulton {F}] [ ANIC Database No./ 29 026577].GoogleMaps 

Paratypes: six micro–pinned reared females (dried with Pelldri II™). Label data: [Para/ type (yellow)] [ Paraustrosimulium  / obcidens  ] [Western Australia / Deeside Coast Rd/ brook/ S34.4380° E116.3863° / alt. 183 m. 9–ix–2014./ Coll. J.K. Moulton {F}] [ ANICAbout ANIC Database No./29 026578-683]. One pinned male, label data as above, but with [{M}] [ ANICAbout ANIC Database No./29 026584]. Two last instar larvae in ETOH. Label data: [Para/ type (yellow)] [ Paraustrosimulium  / obcidens  ] [Western Australia / Goldmine Gully, S32° 24' / E116° 12' / 8 September 1996 / Coll: J. K. Moulton] [ ANICAbout ANIC Database No./29 026626]. Five slide mounts—two, a male and female each from Goldmine Gully. Label data as above, but with [ ANICAbout ANIC Database No./29 026627] and [ ANICAbout ANIC Database No./29 026628]—one a last instar larva, with [ ANICAbout ANIC Database No./29 026631]. Pupa [ ANICAbout ANIC Database No./29 026629] and last instar larva from Deeside Coast [ ANICAbout ANIC Database No./29 026630].

Additional material. ETOH. Mixture of males, female, larvae pupae and exuviae. Label data as for Deeside Coast [ANIC Database No./29 026632]. Slides, adults and one pupa; seven as [ Paraustrosimulium  / obcidens  ] [Western Australia/ Goldmine Gully/ Balmoral State Forest/ Jarradale S32.3900/ E116.2000. alt 280m / 8-ix-1966. Coll. JK/ Moulton] [UASM #370880-370886], four as [ Paraustrosimulium  / obcidens  ] [Western Australia/ Deeside Coast Rd. brook/ S34.4380 E116.3863/ alt 183 m. 9-ix-2014 / Coll. JK Moulton] [UASM # 370887-370890].

Distribution ( Fig. 85View FIGURE 85). Western Australia: Deeside Coast Road, S34.4380° E116.3863° alt. 183 m. 2 & 9–ix– 2014. Coll. J.K. Moulton, D.C. Currie. Styx River, Fernlay Road, S34.8845° E117.1045°, alt. 50 m. 1–ix–2014, 9– xi–2014. Coll. J.K. Moulton, D.C. Currie. Goldmine Gully, Balmoral State Forest, Balmoral Road, Jarrahdale, S32.3900° E116.2000°, alt 280 m. 8–ix–1996. Coll: J.K. Moulton.

Bionomics. Little is known about this species. Collection dates suggest an Austral spring species. The small mouthparts of the female suggests non–biting behaviour, but the virtual absence of abdominal tergites ( Fig. 55View FIGURES 51 – 55) and a well developed tooth on the tarsal claws ( Fig. 54View FIGURES 51 – 55) imply otherwise. New Zealand Austrosimulium ( Craig et al. 2012) blood–feeding species tend to have smaller tergites and it is known an enlarged tarsal claw tooth is common to bird–feeding simuliids ( Adler et al. 2004), so perhaps Paraustrosimulium obcidens is ornithophilic? 

2012) blood–feeding species tend to have smaller tergites and it is known an enlarged tarsal claw tooth is common to bird–feeding simuliids ( Adler et al. 2004), so perhaps Paraustrosimulium obcidens  is ornithophilic?

Habitats of the larvae tend to be slow flowing streams (e.g., Fig. 84View FIGURES 80 – 84), with trailing grass and turbid water.

Remarks. The marked difference in the tarsal claw tooth between apparent sister species is surprising. Paraustrosimulium colboi  females have little in the way of a tooth ( Fig. 12View FIGURES 12 – 17), whereas those of P. obcidens  have a markedly developed tooth separated by a distinct notch from a heel ( Fig. 54View FIGURES 51 – 55), as do P. anthracinum  ( Fig. 96View FIGURES 92 – 96). A similar, smaller notch was noted by Craig et al. (2012) for some species of the ungulatum –group of New Zealand Austrosimulium  , where otherwise, in that genus, a tooth is absent. The large tooth and notch are also seen in some species of Gigantodax ( Wygodzinsky & Coscarón 1989)  . Of note too is the absence of the row of stout spines along the ventral edge of the basitarsus—this is also absent in the ungulatum –species group of Austrosimulium  , and sporadically in others ( Craig et al. 2012). The genital fork of female P. obcidens  ( Fig. 57View FIGURES 56 – 59) is almost an exact match of that for P. anthracinum  ( Fig. 99View FIGURES 97 – 101), whereas male genitalia of P. anthracinum  ( Fig. 109View FIGURES 107 – 110) are markedly similar to that of P. colboi  ( Fig. 24View FIGURES 24 – 25).


Australia, Australian Capital Territory, Canberra City, CSIRO, Australian National Insect Collection