Bunyipellum gladiator ( Moulton & Adler) 2004
Craig, Douglas A., Currie, Douglas C. & Moulton, John K., 2018, Reassignment of Western Australia Paracnephia gladiator Moulton & Adler to a new genus, Bunyipellum (Diptera: Simuliidae), Zootaxa 4375 (3), pp. 341-357 : 342-356
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|Bunyipellum gladiator ( Moulton & Adler) 2004|
Bunyipellum gladiator ( Moulton & Adler) 2004 . New Combination
Cnephia "B", Bedo, in Rothfels 1979: 522. Cytospecies.
Redescription. Adult female (based on numbers of specimens and original description). Body ( Fig. 1 View FIGURES 1–7 ): head dark brown, thorax reddish orange, abdomen blackish; total length 3.6–3.8 mm. Head ( Fig. 2 View FIGURES 1–7 ): overall dark in colour; width 0.94–1.10 mm; depth 0.54–0.60 mm; postocciput not markedly hirsute, frons expanded dorsally, broad, dark brown–black; frons-head ratio 1.0:4.5. Eye: interocular distance ca. 0.20–0.22 mm; all ommatidia similarly pigmented, diameter 0.012 mm; ca. 30 rows across and 36 down at mid–eye. Clypeus: width 0.23 mm, expanded ventrally; mottled medium brown, vestiture of sparse hairs. Antenna ( Fig. 3 View FIGURES 1–7 ): 9 flagellomeres, extended beyond head margin; total length 0.7–0.8 mm; evenly pale brownish yellow; pedicel smaller, scape larger than flagellomere I, others similar in size basally, slightly elongated distally, barely tapered to apex. Mouthparts: well developed, ca. 0.45x length of head depth; maxillary palpus ( Fig. 5 View FIGURES 1–7 ), relatively short, total length 0.68 mm, palpomeres I & II small, palpomere III darker brown than remainder, dense vestiture, IV small, V (distal) short; proportional lengths of palpomeres III–V 1.0:0.6:0.8; sensory organ ovoid, 0.3x length of palpomere III, opening broad, 0.6x width of vesicle; mandible ( Fig. 6 View FIGURES 1–7 ) with ca. 35 small inner teeth (44–50 in original description), 16 outer teeth; lacinia with ca. 17 and 13 teeth on inner and outer edge respectively; cibarium ( Fig. 4 View FIGURES 1–7 ) with cornuae broad and sclerotized apically, lightly sculpted, median gap broadly U-shaped with median projection, setae and armature absent. Thorax: length 1.4–1.7 mm; width 1.2–1.3 mm; evenly dark reddish orange with faint medial and lateral vittae and sparse black hairs; postpronotal lobe slightly paler, well developed; scutellum markedly pale with vestiture of long sparse lateral brown hairs; scutellar depression darker with sparse black hairs; postnotum dark brown, antepronotal lobe (aka propleuron) well developed with small array of vertical pale hairs, proepisternum and fore coxa with sparse pale hairs; pleuron brown, anepisternal (aka plural) membrane dark gray, lacking hairs; katepisternum darker, sulcus distinct and broad. Wing ( Figs. 1, 7 View FIGURES 1–7 , 8 View FIGURES 8–12 ): slightly fumose, length 3.4–4.4 mm; width 1.4–1.5 mm; anterior veins markedly brown, substantial, small basal cell distinct; a:b ratio 1.0:2.8; distal 2/3 of costa with hairlike setae proximally, mixed with spine-like setae distally, base of radius and R1 with hair-like setae dorsally, Rs with no trace of apical fork; false vein forked, M1 appearing double; CuA1 straight, not reaching wing margin (original description has it so), CuA2 sinuous, reaching wing margin; A1 curved distally, not reaching wing margin; A2 with sclerotized base in anal angle. Haltere: stem tan, knob white to beige. Legs ( Figs. 1 View FIGURES 1–7 , 9 View FIGURES 8–12 ): evenly pale yellow; femora and tibiae slightly darker apically, hind basitarsus with ventral regular row of stout spines; calcipala small, less than 1/4 length of tarsomere II, with concentration of spines; pedisulcus essentially absent, as minor wrinkles; tarsomere II expanded distally, 2.5x longer than distal width; claws ( Fig. 10 View FIGURES 8–12 ) with talon smoothly tapered, basal tooth absent, rarely with small, sub-basal tooth, heel of claw moderately expressed and clear. Abdomen: in ETOH, dark greyish brown; basal scale (tergite I) mottled pale and dark grey with short pale hairs; anterior segments dark grey, segments posterior of V, darker brownish black; tergites poorly sclerotized and yellowish, tergite II markedly broad ( Fig. 11 View FIGURES 8–12 ), membranous areas grey. Genitalia: markedly small, yellowish; sternite VIII with distinct median region, vestiture of microtrichial arrays, large strong hairs posterolaterally; hypogynial valves ( Fig. 14 View FIGURES13–15 ) markedly pale, vestiture of triads of microtrichia and strong hairs, median edges of valves distinctly concave, not strengthened, apices broadly rounded, insubstantial and colourless; genital fork ( Fig. 12 View FIGURES 8–12 ) elegant, anterior arm long and narrowed in expression, slightly expanded apically, no indication of membranous lateral areas, lateral arms narrowed, apodeme absent, posterolateral expansions well developed; spermatheca large, ovoid, ( Fig. 13 View FIGURES13–15 ), surface smooth, internal fine spines (or acanthae) present in arrays of 4 to 5, small and hard to observe, clear area around junction with spermathecal duct small, sculpting minimal; cercus in lateral view ovoid, lightly pigmented; anal lobe rounded, substantial, more heavily pigmented ( Fig. 15 View FIGURES13–15 ).
Adult male (based on numerous specimens and original description). Body (Fig. 16): overall tri-coloured, thorax reddish orange, legs pale yellow, abdomen black; total body length 2-6– 3.3 mm. Head (Fig. 17): width 1.0 mm; depth 0.7 mm. Eyes: upper ommatidia colour dark orange, not markedly enlarge, diameter 0.033 mm, ca. 23 across and down; lower smaller ommatidia black to blackish orange, diameter 0.018 mm, ca. 24 across, 36 down. Clypeus: mottled black; width 0.2 mm; vestiture of sparse fine black hairs. Antenna: overall yellow, total length 0.71–0.73 mm; pedicel and scape dark brown; scape short, pedicel wider than broad, flagellomere I narrower than scape and longer than broad, remaining flagellomeres evenly yellow and tapered smoothly to elongated apical flagellomere. Mouthparts: insubstantial; length 0.3x head depth; maxillary palpus (Fig. 18) 0.6 mm long, palpomere III dark and tubular, extended distally, palpomeres IV smaller, palpomere V subequal in length to III, proportional lengths of III–V palpomeres 1.0:0.7:1.0, sensory vesicle minute, spherical, occupying 0.3x length of palpomere III, opening 0.33x width of vesicle; lacinia small with apical hairs; mandible lacking teeth. Thorax: markedly domed (Fig. 16), head angled anteriorly; length 1.2 mm; width 1.1 mm; postpronotal lobe concolourous with scutum, hairs longer; scutum mottled reddish orange, vestiture of sparse recumbent fine pale hairs, longer in scutellar depression; scutellum markedly paler than scutum with long black hairs laterally, postnotum darker than scutum, antepronotal lobe and proepisternum haired; pleurae darker than scutum, katepisternum dark brown, sulcus distinct, albeit shallow. Wing ( Fig. 19 View FIGURES 19–23 ): length 2.8–3.2 mm, width 1.4 mm; basal cell present, but minute; a:b ratio 1.0:3.0; otherwise as for female. Haltere: stem pale, knob grey. Legs: overall yellowish, hind basitarsus slightly expanded medially, ventral row of stout spines, calcipala and pedisulcus as for female; tarsal claw and grappling pad normal. Abdomen ( Fig. 20 View FIGURES 19–23 ): black; basal scale (tergite I) black, hairs pale and long, extended to posterior of tergite II, tergites all markedly broad and equally sclerotized; sternite I present, II absent, III and those more posterior distinct, pleural cuticle concertinaed. Genitalia (Figs. 16, 21–23): protruded ventrally, markedly pale yellow; gonocoxa 1.1x longer than basal width, vestiture of sparse hairs, slightly protruded ventral edge at gonostylus articulation; gonostylus in lateral view tapered markedly to narrow apex, approximately 1.8x longer than basal width, two short, blunt, apical spines; ventral plate poorly sclerotized, slightly wider than long, corrugated anterolaterally, vestiture absent, except for sparse hairs on narrow median carina, posterior apex broadly domed, membranous laterally, shallowly convex anteromedially, basal arms broadly expressed; median sclerite as two short sclerotized arms projected posteriorly beyond ventral plate; paramere connector thin and closely applied to lateral edges of ventral plate, parameres plate-like basally, slightly strengthened along one edge, tapered distally to unpigmented crenulated band of cuticle connected to sparse small spines on slightly strengthened area; adeagal membrane otherwise bare.
Pupa (based on numerous specimens). Body ( Fig. 24 View FIGURES 24–27 ): length, female 3.8–4.6 mm, male 3.6–4.1 mm, brown, markedly sclerotised cuticle. Head: frons of female short ( Fig. 25 View FIGURES 24–27 ), narrowed basally, angulate with ratio of basal width to vertex width 1.0:1.6 and width to length 1.0:1.4, that of male ovoid ( Fig. 26 View FIGURES 24–27 ), narrowed basally; ratios 1.0:1.8 and 1.0:2.3, respectively; cuticle with sparse granules in the male, more so in female; frontal and facial setae present, but poorly expressed, epicranial setae markedly expressed as long stiff spines, the dorsal-most extremely so, on raised bases. Thorax: shiny, smooth, generally lacking granules; setae spine-like in 4 transverse rows, anterior-most of 2 elongated and darkly pigmented spines, second row of 4; third row of 2 or 3 slender, hairlike setae, fourth row of 1 hair-like pair and 1 elongate, darkly pigmented pair of setae. Gill ( Figs. 24 View FIGURES 24–27 , 38 View FIGURES 37–42 ): ca. 60 light grey, non-tapered finger-like filaments arising directly from knob-like base, maximum length 0.8 mm; some filaments short, other branching once or twice at various length; filament surface lacking annulations, densely packed with trabeculae ( Fig. 39 View FIGURES 37–42 ). Abdomen ( Fig. 27 View FIGURES 24–27 ): sclerites light brown with dense granules; tergite I with 6–8 slender setae and central pair of short darkly pigmented spines on raised bases; tergites II–VII with raised ridge posteriorly, tergite II with 3 or 4 fine setae and 10–12 longer, stouter setae along posterior margin; tergites III and IV with 3 or 4 fine setae and 12–14 stout, anteriorly directed, darkly pigmented hooks; tergite V with 8 fine setae and 8 stout, anteriorly directed, darkly pigmented hooks; tergite VI with 9 or 10 fine setae and 2 anteriorly directed hooks (sometimes set in pleural membrane); tergite VII with 6–8 fine setae; tergite VIII with 10–12 fine setae; tergite IX with 4 darkly pigmented setae, terminal spines elongated and sharp; tergites IV–IX with anterior row of variously developed spine combs; pleurites absent; pleural membrane of segments IV–VII with 2 or 3 stout, darkly pigmented, anteriorly-directed hooks per side, that of segment VIII with 2 setae per side, segment IX with cluster of 4 or 5 elongate, darkly pigmented setae per side; abdominal sternites V and VI with 2–6 fine setae and 6 stout, anteriorly directed, darkly pigmented hooks; sternite VII with 4 stout, anteriorly directed, darkly pigmented hooks; sternite VIII with 2 slender setae; sternite IX lacking grapnel hooks, but with cluster of stiff, slightly curled spines ( Fig. 28 View FIGURE 28 ). Cocoon ( Fig. 24 View FIGURES 24–27 ): Close fitting, occasionally may cover complete pupa, extends beyond pupae ventrally, variable; dense weave; often retaining larval exuviae.
Larva (based on numbers of last instar specimens and original description). Body (Fig. 30): total length variable, 6.4–8.9 mm, substantial and muscular. Colour, overall, mottled dark brown. Head (Fig. 29): evenly medium brown, apotome slightly lighter than genae; head spot pattern poorly expressed, but tending to negative, irregular darker pigment posterolaterally; cuticle thickness exacerbated, with lateral corrugations; cephalic setae not evident; ecdysial sutures distinct, essentially straight, slightly expanded posteriorly; head depth and width increased markedly anteriorly, dimensions variable, length 0.86–1.20 mm, at mid head width 0.61–0.89 mm; distance between antennal bases 0.44–0.55 mm; head widest across base of fans; cervical sclerites elongated laterally with rounded region posteromedially, not obviously attached to postocciput. Antenna ( Fig. 31 View FIGURES 31–36 ): subequal in length to fan stem; usually directed more laterally and often posterolaterally (e.g. Fig. 29); total length 0.35– 0.35 mm, apical and medial antennomeres subequal in length, basal antennomere clear except for lateral apical portion, markedly shorter than medial antennomere, that evenly dark brown, except for lateral apical portion, apical antennomere slightly expanded basally and apically, dark brown, proportional lengths of antennomeres 1.0:1.7:1.7. Labral fan: stalk markedly short, broad and sclerotized posteriorly, expanded anteriorly, 75 – 88 dark brown, markedly substantive rays, ten posterior rays slightly finer than remainder, bases exacerbated and darkly pigmented, ray length 0.92 – 1.02 mm, mid width 0.03 mm; microtrichia long, no pattern, length subequal to ray width. Mandible ( Figs. 32, 33 View FIGURES 31–36 ): well pigmented; apical brush exacerbated; apical teeth narrowed; outer teeth small, apical tooth moderately developed; preapical teeth small and subequal in length, ca. 12 spinous teeth of similar length; serration and sensillum as single unit; blade region short and straight. Maxilla ( Fig. 34 View FIGURES 31–36 ): lobe small, palpus black, 2.2x as long as basal width; hair tuft at base of palp markedly developed. Postgenal cleft ( Fig. 35 View FIGURES 31–36 ): angulate, V-shaped apex; posterior tentorial pits not markedly developed; postgenal bridge not markedly lighter than genae; elongated posteroventral muscles spots distinct; ratio of hypostoma: genal bridge: cleft, 1.0:2.0:1.0; ventral cuticle of head with lateral corrugations. Hypostoma ( Fig. 36 View FIGURES 31–36 ): darkly pigmented; not markedly extended anteriorly, anterior margin concave; teeth short, blunt, subequal in height; tooth 0 (median) small and sharp, as is tooth 1 (sublateral), tooth 2 & 3 similar, all partially obscured by ventral edge of hypostoma, tooth 4 (lateral) sharp medially, flanged laterally to tooth 5—the most prominent, albeit largely obscured by hypostomal edge, teeth 6 & 7 barely evident, all teeth variable; lateral serrations absent; 2 or 3 setae per side, short. Thorax ( Fig. 37 View FIGURES 37–42 ): pupal gill histoblast with ca. 8 filament bases visible; with head to the right filaments descend vertically then curl slightly clockwise, with filament tips then slightly angled counterclockwise; gill ( Figs. 38, 39 View FIGURES 37–42 ) as described under pupa. Anterior proleg ( Fig. 40 View FIGURES 37–42 ): proximally well expressed, but circlet of hooks small, two hook sizes, lateral sclerites absent (described as present in original description). Abdomen: medium to dark greyish brown, anterior segments banded, posteriorly not; gradually expanded posteroventrally to seventh segment, sharply contracted at last segment. Integument with minute, subparallel, crenulate ridges dorsally ( Fig. 41 View FIGURES 37–42 ) and rounded granules ventrally. Ventral tubercles: absent. Anal sclerite ( Fig. 42 View FIGURES 37–42 ): markedly finely expressed; anterior arms short and flared distally, median region not markedly developed, posteroventral arms twice as long as anterior arms, finely tapered, distal half crenulated. Rectal papillae: three simple lobes. Posterior circlet: overall small, but with hooks darkly pigmented and distinct; numbers of hooks low, 44–48 rows with 7–11 hooks per row (total ca. 440).
Etymology. As given in Moulton, Adler & Prince (2004: 6), the species name refers to the stout, elongated setae (aka trichomes) on the pupal head and thorax.
Types. The holotype and some paratypes are deposited in the Western Australia Museum, Perth. Additional paratypes are in the Australian National Insect Collection ( ANIC), Canberra; Natural History Museum, London ; United States National Museum of Natural History, Washington, DC; Canadian National Collection, Ottawa; and Clemson University Arthropod Collection, Clemson, South Carolina (Moulton et al. 2014: 3).
Additional material Some material of all stages is now in the Strickland Museum, University of Alberta; ETOH ( UASM # 354037 – 354050); slides ( UASM # 353351 – 353359). Five dried pinned females from Deeside Coast Road are deposited in ANIC ( ANIC Database No. / 29 0 26585, 29 0 26737 – 29 026740). The remainder of the original material is in the personal collection of J. K. Moulton (JKM).
Distribution ( Fig 43 View FIGURE43 ). Known only from the Jarrah Forest and Warren regions of Western Australia.
Kangaroo Gully, Brookton Hwy. (Rt. 40), Jarrah Forest, Darling Reserve , S32.1170° E116.1500°, alt. 230m., 21 August 1973, Coll. J. Prince GoogleMaps ; 7 September 1996, Coll. J.K. Moulton. Quinine Gully, Ashendon Hwy. , S32.1500° E116.1920°, alt GoogleMaps . 260m., 7 September 1996, Coll. J.K. Moulton. Churchman’s Brook, Canning Dam Road , S32.1879° E116.1163°, alt GoogleMaps . 282m., 8 September 1996, Coll. J.K. Moulton. Goldmine Gully, S32.4054° E116.2023°, alt. 270m., 8 September 1996, Coll. J.K. Moulton. Mumballup, S33.5300° E116.1100°, alt. 133m., 13 September 1974, Coll. D.G. Bedo. Shannon National Park, Deeside Coast Road, S34.7767° E116.3157°, alt GoogleMaps . 80m., 5 November 2003, Coll. A. Zwick.
Bionomics. Moulton et al. (2004: 8) note that larvae and pupae occupy riffles in shaded small to medium-sized streams in the Jarrah Forest region of the Darling Range in Western Australia. Found only during the Austral late winter and early spring, Bunyipellum gladiator is assumed to be univoltine. Females are attracted to humans but are not known to blood feed on such hosts. The substantial mouthparts ( Fig. 2 View FIGURES 1–7 ), well-toothed mandible ( Fig. 6 View FIGURES 1–7 ), plus relatively small abdominal tergites ( Fig. 11 View FIGURES 8–12 ) suggest that females of B. gladiator are capable of blood feeding. Presence of a simple claw ( Fig. 10 View FIGURES 8–12 ) indicates that the species is not ornithophilic (Adler et al. 2004).
Remarks. Female adults, apart from possessing large mouthparts, have a maxillary palp ( Fig. 5 View FIGURES 1–7 ) unique for Australian simuliids. Palpomeres I and II are larger than others, III is subequal in length to palpomere V, with IV markedly small. For the wing, the radius and radial sector veins parallel one another and are not closely applied as in Austrosimulium (Craig et al. 2014: 210) . The calcipala possess a clump of spines and this condition is also seen in Paracnephia fergusoni ( Tonnoir 1925: 221) and other now-known Australian simuliids. Moulton et al. (2004: 1, 4) describe the calcipala as 'large'; however, as noted above, other simuliids possessing a poorly expressed or small calcipala have a similar clump of spines to B. gladiator , so we consider that its calcipala to be small, albeit distinct—it is less than quarter the length of the second tarsomere and 0.4x the width of the basitarsus apex. The calcipala ( Fig. 22 View FIGURES 19–23 ) is, however, of similar development to those of Araucnephia and Araucnephoides, but no mention in descriptions is made of presence or absence of a ventral row of hind basitarsus spines ( Wygodzinsky & Coscarón 1973). Araucnephia, Araucnephoides and Bunyipellum all lack a pedisulcus. Absence or poorly expressed claw basal tooth in female Bunyipellum ( Fig. 10 View FIGURES 8–12 ) is now also known for some Australian Gondwanan simuliids, whereas Araucnephia and Araucnephoides possess a moderately-sized basal tooth. The cerci and anal lobe of the female are markedly protruded ventrally ( Fig. 1 View FIGURES 1–7 ), yellowish and distinct. Moulton et al. (2004) noted that the median sclerite of male genitalia of B. gladiator was similar to that of Araucephia montana Wygodzinsky & Coscarón , but made no other comparisons regarding the genitalia. Overall, however, the genitalia are markedly congruent, with similarities in the narrowed gonostylus and two terminal spines, ventral plate, paramere connector, paramere and spines (Wygodzinsky & Coscarón loc cit.: 169). In Bunyipellum gladiator , the narrow gonostylus with two terminal spines is unique for Australian Gondwanan simuliids and, in general, at considerable variance to males of Austrosimulium ( Craig et al. 2012) . The paramere and parameral spines (less so the paramere connector), are of similar expression to those in Paraustrosimulium ( Craig et al. 2017) .
The pupa and cocoon structure of B. gladiator suggest adaptation for high velocity flow and are, therefore, something of a conundrum. Pupae occur in shallow riffles of small streams where water velocity, albeit relatively high in some instances, does not exert marked force. The terminal spines on the pupal abdomen are moderately long and sharply pointed ( Figs. 27 View FIGURES 24–27 , 28 View FIGURE 28 ) with the probable function of holding the pupa within the cocoon. Indeed, the terminal spines can be seen protruding through the cocoon ( Fig. 24 View FIGURES 24–27 ). The raised ridges with fine armature on some of the tergites ( Fig. 27 View FIGURES 24–27 ) also suggest a similar adaptation. However, the spine-like setae on the thorax ( Fig. 24 View FIGURES 24–27 ) and head capsule (unique among the Australian Simuliidae ) ( Figs. 25, 26 View FIGURES 24–27 ) are not always covered by the cocoon and are, perhaps, protective devices for the gill, or against predators. The pupae of Araucnephia and Araucnephoides have little in common with that of B. gladiator , lacking the major thoracic spines, raised abdominal tergite ridges and large terminal spines. Notwithstanding, all three genera lack well developed grapnel hooks on the IX segment, with the homologs either straight in Bunyipellum ( Figs. 27 View FIGURES 24–27 , 28 View FIGURE 28 ) or slightly curled in Araucnephia . Bunyipellum has many more pupal gill filaments than either of the two South American genera.
The larvae of Bunyipellum gladiator are a puzzling mixture of character states. The substantial body and shape with the expanded posteroventral abdomen (Fig. 30) are found in other simuliid larvae that inhabit fast water, such as, for example, Paracnephia strenua (Mackerras & Mackerras) , Simulium (Inseliellum) tahitiense Edwards and Simulium (Gomphostilbia) palauense Stone. An expanded abdomen appears to enable simuliid larvae to clump together to produce skimming flow, a common ploy to reduce drag forces ( Nowell & Jumars 1984: 317), yet still remain sufficiently upright for the fans to be oriented into the flow. Larvae of B. gladiator are found in the riffles of small streams as described above for pupae. Although water velocity is sometimes moderate to high in such habitats, the shallow depth ensures that shear stresses are low.
The labral fans are unique for Australian simuliids (Fig. 29). The expression of the fan stalk, short and broad is not seen in others and the rays are heavily expressed and numerous. These do not fit the fan structure model proposed by Palmer & Craig (2000: 213) for simuliid larvae inhabiting higher velocities and what we assume as medium level seston.
The larval antenna, with its unusual short proximal article ( Fig. 31 View FIGURES 31–36 ), is unique among the Australian Simuliidae , but is markedly similar to those of the South American genera Araucnephia and Araucnephoides larvae. This possibly represents a synapomorphy of these three genera. Antennae subequal in length to, or shorter than the labral fan stem are commonly expressed in simuliid larvae that inhabit fast flowing water ( Crosskey 1990: 108, Adler et al. 2004: 153), again somewhat paradoxical in Bunyipellum given the known habitats of larvae. Long antennae are seen in aquatic insects in slow-flow habitats and are so expressed to penetrate the attached boundary layer ( Craig 1990: 349).
No comment was made by Moulton et al. (2004) about the unusual concave configuration of the larval hypostoma ( Fig. 36 View FIGURES 31–36 ). A similar arrangement is found in the larvae of the Ectemnia Enderlein , which attach themselves to a silk stalk ( Moulton & Adler 1997). Details of the attachment behaviour of B. gladiator larvae remain unknown; however, it seems unlikely that Bunyipellum and Ectemnia —a northern hemisphere genus—share an immediate common ancestry. The hypostomal teeth of Bunyipellum differ markedly from those of Araucnephia and Araucnephoides in that the former are uniformly small ( Fig. 36 View FIGURES 31–36 ), contrasting markedly with the well expressed teeth in the latter two genera. The postgenal cleft of Araucnephia montana can be angulate, similar to that of B. gladiator ( Fig. 35 View FIGURES 31–36 ), albeit shallower.
The anterior thoracic proleg circlet of hooks is uniquely small for Australian simuliids. This proleg is used by simuliid larvae to grasp a pad of salivary silk when moving position and before the posterior proleg hooks are attached ( Barr 1984). The small size is suggestive of adaptation to habitats with low velocity. A similar pattern is seen in the circlet of hooks of the posterior proleg. With only ca. 440 hooks, the posterior proleg conforms to other simuliids that inhabit slow-flow habitats ( Palmer & Craig 2000: 204, and others). The hooks are, however, enlarged and markedly sclerotized ( Fig. 42 View FIGURES 37–42 ). The anal sclerite is delicately expressed, similar to certain other low-flowinhabiting Australian simuliids, such as Paracnephia umbratora (Tonnoir) . In that species, however, reduction is different and related to the habit of attaching to a thread ( Moulton & Adler 1997: 1907). These morphological expressions of structures of larval B. gladiator are suggestive of finer-scale behaviours that warrant further study.
Moulton et al. (2004: 3) and Adler & Crosskey (2015: 31) both included “ Cnephia B” of Bedo in Rothfels (1979: 522) in their synonymical list of P. gladiator . We have confirmed (Bedo, pers. comm. 2017) that this informal cytological designation indeed refers to Bunyipellum gladiator . The chromosomes have distinct centromere bands, an expanded region in CI, undifferentiated sex chromosomes (Xo Yo) and no inversion polymorphism.
With its suite of unique morphological characteristics and lack of congruence with other Australian simuliids, we consider these to be sufficient grounds to assign B. gladiator to its own monospecific genus, with possible relationship to South American Araucnephia and Araucnephoides.
Concluding comments. Most other Gondwanan Simuliidae of Australia have east-west sibling species or segregates separated by the Nullarbor desert region; a common situation for Australian biota. Bunyipellum is so far known exclusively from southwestern Australia—a pattern confirmed from our own wide-ranging collections (e.g. Craig et al. 2017), and those of earlier specialists (e.g. Mackerras & Mackerras 1952, Colbo 1974, and others). Known localities for B. gladiator are from a region along the Darling Escarpment in what is referred to as the Jarrah Forest Bioregion on the western edge of the ancient Yilgarn Craton. The collection by A. Zwick, 2003, was to the far southwest in the Warren Bioregion ( Fig. 43 View FIGURE43 ).
A wide-ranging analysis of south-western Australian faunistic biogeography by Rix et al. (2015) lists key geographic and climatic events for this region and Australia as a whole. These include separation of southern Western Australia from Eastern Antarctica at ca. 96 mya (Cretaceous), complete separation of eastern Australia at ca. 32 mya (Early Oligocene) with commencement of aridification and of inundation of the south-central Australia Nullarbor region by the Eromanga Sea, with deposition of limestones at ca. 25 mya (Late Oligocene), such ending at ca. 14 mya (Mid Miocene) with the Nullarbor surface becoming exposed. Rix et al. (loc. cit.) used published, dated, molecular data sets to determine time of divergence of south-western Australian fauna from that of the south-east. What they refer to as “Tier 1 divergences” (their Fig. 5 View FIGURES 1–7 ), fall mainly between the Early and Mid Miocene (ca. 24-6 mya). Of significance here, perhaps, is an older one (ca. 54-26 mya) suggested for the chironomid Stictocladius (Edwards) by Krosch & Cranston (2013).
Krosch & Cranston (loc. cit.) in their detailed examination of molecular phylogenetics, biogeography and evolutionary tempo of Stictocladius —a genus with Gondwanan distribution ( Australia, New Zealand, South America)—concluded that divergence of the main lineages was Late Cretaceous (ca. 66 mya). Divergences of the Australian 'multiserialis' segregates were Late Eocene to Late Oligocene (ca. 45-26 mya). That for the 'sofour' lineages, may have been similar (ca. 45 mya), but apparently more recently in the Miocene (ca. 22-5 mya). Divergence of the east and west groups of ‘multiserialis’ appears to have been at ca. 40 mya (Mid Eocene), with further divergence of the eastern segregates continuing between the late Paleogene and early Neogene (36-11 mya).
Timing of later Tier 1 events of Rix et al. (loc. cit.), plus later divergences given above for Stictocladius segregates, might apply to presently known east-west distribution of Australian simuliid fauna (e.g., Mackerras & Mackerras 1952: 113, Craig et al. 2017). Given the unusual morphological character states of Bunyipellum gladiator , absence of any Australian sister group, plus possible relationship to South American Araucnephia and Araucnephoides, it seems possible that divergence of Bunyipellum was from a common precursor on Gondwana prior to separation of Australia and Antarctica, of possible similar ilk to Stictocladius —that is, Late Cretaceous or earlier. Bunyipellum , if not among the oldest lineages of Australian Gondwanan Simuliidae , is certainly one of the most unusual.
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