Protaustrosimulium, Currie & Craig & Moulton, 2018

Currie, Douglas C., Craig, Douglas A. & Moulton, John K., 2018, A new genus, Protaustrosimulium, for four species of Australian black flies (Diptera: Simuliidae), Zootaxa 4521 (3), pp. 301-334 : 302-304

Protaustrosimulium n. gen. Currie, Craig & Moulton

Type species: Cnephia pilfreyi Davies & Györkös 1988: 107 .

Members of the Protaustrosimulium terebrans -group, as defined below (i.e., Prot. terebrans and Prot. opscurum n. sp.) are known only as adult females. Accordingly, the following diagnosis is confirmed just for that particular life stage. Character states of males, pupae and larvae apply definitely only to members of the Prot. pilfreyi -group; however, a subset of these states may eventually prove to be diagnostic of the genus as a whole.

Diagnosis. Female: small, darkly coloured flies. Head: antenna with nine flagellomeres. Lateral cervical sclerites well expressed. Thorax: not markedly domed; katepisternal sulcus well defined and more or less complete anteriorly; katepisternum and anepisternal membrane bare. Wing: rather fumose, especially apically, with darkly pigmented veins; basal medial (bm) cell present, but minute (absent in male of Prot. pilfreyi ); membrane surrounding r-m junction not markedly pigmented; a:b ratio ca. 1.0:2.8; Costa with short spinules interspersed among typical setae on apical half; vein Rs unbranched; R 1 and R s closely approximated distally, confluent before junction with C; basal section of R haired; M 1 appears doubled distally; CuA slightly sinuous. Legs: basitarsus without row of stout spines ventrally; calcipala well developed, with base one-third to one-half width of hind basitarsus apex; pedisulcus present but variously expressed; tarsal claws smoothly and shallowly curved, with small basal tooth arising from medial side of claw, heel small to well expressed. Genitalia: spermatheca with pigmentation extended markedly onto apex of spermathecal duct (condition unknown in Prot. opscurum ). Male: details of head, thorax and wing as described for females. Genitalia: gonostylus slightly shorter than gonocoxite, with three to five short apical spines; ventral plate trapezoidal shaped, with distinct median keel; paramere platelike, subtriangular, with four long apical spines; aedeagal membrane with microtrichia; median sclerite deeply forked. Pupa: gill thin-walled and transparent, consisting of 6–10 short finger-like filaments; thoracic notum smooth, with typical array of setae; abdominal cuticle thin and lightly pigmented; pleurites absent; abdominal armature sparse, with hooks present only on tergites V and VI; spine combs minute, present on tergites VI–IX; anchor-shaped hooks present on pleura of terminal abdominal segments; terminal spines minute. Cocoon: shoeshaped or slipper-shaped, without anterior rim, constructed of fine loosely woven silk covering most of pupa. Larva: antenna extended well beyond apex of labral fan base; article length ratio (basal:medial:distal) ca. 3:1:7; basal and medial articles relatively thick and brown, distal article relatively thin (ca. one-third width of other articles) and hyaline; cervical sclerites not fused to postocciput; hypostoma with apical teeth not arranged on prominent lobes; teeth partially covered by ventral wall of hypostoma; tooth 0 and 4 most prominent; lateral serrations absent; postgenal cleft virtually absent, represented at most by narrow inverted-V shaped notch; abdomen with ventral tubercles well expressed; anal sclerite X-shaped, interarm struts absent; accessory and semicircular sclerites present; rectal papillae of three simple lobes.

Distribution. Australia; with species distributed vicariously in New South Wales, the Australian Capital Region and Victoria in the southeast, and Western Australia in the west.

Etymology. In reference to the apparent close relationship between the species under consideration to Austrosimulium , Paraustrosimulium and Cnesiamima Wygodzinsky & Coscarón 1973 .

Constituents. Protaustrosimulium pilfreyi (Davies & Györkös) n. comb. Prot. amphorum n. sp., Prot. terebrans (Tonnoir) n. comb, and Prot. opscurum n. sp.

Discussion. Protaustrosimulium n. gen. is here established for four species of Australian black flies that share a close relationship with Austrosimulium , Paraustrosimulium , and Cnesiamima . They share with Austrosimulium a markedly similar wing venation, wherein R 1 and R s are closely approximated distally, becoming confluent before joining the costa. (e.g., Figs. 29 , 30 ). This state is clearly synapomorphic for members of these two genera, as R 1 and R s join the costa separately in Paraustrosimulium , Cnesiamima and all other simuliids. The wings of all four genera have a similar a:b ratio (i.e., they all have a relatively short basal radial (br) cell that extends ca. one fourth length of wing as measured from cell base) and possess a small but distinct basal medial (bm) cell. Although the immature stages are unknown for members of the terebrans -group, larvae and pupae of the pilfreyi -group share a number of synapomorphic character-states with Austrosimulium , Paraustrosimulium and Cnesiamima . One such state is the elongate distal antennal article of larvae, which is two times or more the length of the basal and medial article combined. The hypostoma of the four genera are also similar in that their apical teeth are not grouped on prominent lobes and further are partially covered by the ventral wall of the hypostoma (e.g., Fig. 16 ). Another character-state shared between Protaustrosimulium and Austrosimulium s. str. (but not by Austrosimulium (Novaustrosimulium) , Paraustrosimulium and Cnesiamima ) is presence of accessory and semicircular sclerites on the posterior proleg of larvae. Although similar structures occur elsewhere in the Simuliidae , such as in Parasimulium crosskeyi Peterson, Gigantodax Enderlein , Simulium (Gomphostilbia) palauense Stone ( Takaoka & Craig, 1999) and Crozetia Davies (Craig et al., 2003) they are likely to be independently evolved based on marked differences in their expression. As shown by Craig et al. (2012: 285), a clear ring of cuticle surrounds and supports the circlet of hooks, and while parts of the ring may be darkly pigmented, as is the case in most Austrosimulium species and members of the Prot. pilfreyi- group ( Figs. 21 , 66 ), the structure is actually present in all simuliid larvae examined. The semicircular sclerite then, when expressed, is merely pigmentation of the ring. Accordingly, while this underlying cuticle is homologous across the Simuliidae , its expression, when sclerotized and pigmented, is subject to homoplasy. Nonetheless, the form of the accessory and semicircular sclerites is markedly similar in members of the pilfreyi -group and Austrosimulium s. str., perhaps suggesting a common origin. Pupae of Protaustrosimulium , Austrosimulium , Cnesiamima and Paraustrosimulium are similar in that their abdominal armature is weakly expressed, the terminal spines are minute ( Fig. 55 ), and the pleura of the terminal segments are endowed with anchor- or grapnel-shaped hooks. Finally, the hind basitarsus of female Protaustrosimulium , plus those of A. australense and members of the A. ungulatum species-group, lack a row of stout setae that runs parallel to the comb in other simuliids ( Craig et al., 2012: 54). This character state either provides further evidence of a close relationship between Protaustrosimulium and Austrosimulium , or perhaps represents a synapomorphy (albeit a homoplasious one) of the new genus.

Although Protaustrosimulium shares many of the above-mentioned features with Austrosimulium and Paraustrosimulium , it lacks synapomorphies that link those latter two genera together. For example, Protaustrosimulium has nine (as opposed to eight) antennal flagellomeres, and lacks (as does Cnesiamima ) interarm struts on the anal sclerite. Protaustrosimulium can be further distinguished from Austrosimulium in lacking the following autapomorphies of that genus; namely, Protaustrosimulium females have serrations on both sides of the mandible (as opposed to just on the inner side), and their pupae have spine combs on abdominal tergites VI–VIII (as opposed to lacking spine combs altogether). In summary, the character state distribution in Protaustrosimulium is muddled, with different sets of relationships suggested depending on how characters are interpreted. Arbitrary assignment of the species in question to either Austrosimulium or Paraustrosimulium would render diagnosis of those genera difficult. We therefore prefer to recognize a new genus in order to maintain current generic concepts as far as possible. An alternative approach would be to recognize just a single Austral genus— Austrosimulium s. lat. —with five subgenera, viz., Austrosimulium s. str., Novaustrosimulium, Paraustrosimulium , Cnesiamima and Protaustrosimulium . However, as noted above, marked structural disparity among included taxa would make generic diagnosis difficult.

While it is clear that Protaustrosimulium shares an immediate common ancestry with Austrosimulium , Paraustrosimulium , and Cnesiamima , monophyly of the new genus is less certain—mainly because adult females are the only life stage known for all four species. One possible synapomorphy is a spermatheca with pigmentation extended markedly into the apex of the spermathecal duct. Unfortunately, however, the spermatheca of Prot. opscurum is unknown, and this particular state is variously expressed in other simuliids, including Cnesiamima and Paraustrosimulium . Males and immature stages of the terebrans -group are needed to more fully assess monophyly of Protaustrosimulium as here defined.

The distribution of Protaustrosimulium ( Fig. 99 ), with sister species split between southern Western Australia and the southeastern States, follows closely that of the other Gondwanan simuliid taxa. This, as discussed by Craig et al. (2017, 2018a, 2018b) and Moulton et al. (2018) likely involved inundation of the Nullarbor Plain area by the Eromanga Sea during the Eocene and Miocene, and subsequent desertification.

pilfreyi -group. Genital fork with rod-like anterior arm and membranous lateral region ( Figs. 5 , 35 ).

Constituents. Protaustrosimulium pilfreyi ( Davies & Györkös 1988) and Protaustrosimulium amphorum n. sp.

Figures

FIGURES 30. Protaustrosimulium amphorum. Female adult. Wing. Scale bar = 0.5 mm.

FIGURE 99. Distribution of Protaustrosimulium. (99) Map of southern portion of Australia.

FIGURES 28, 29. Protaustrosimulium amphorum. Female adult. (28) Cibarium. Scale bar = 0.1 mm. (29) Wing veins. Scale bar = 0.5 mm.

FIGURES 14–19. Protaustrosimulium pilfreyi. Last instar larva (Grampians; except Fig. 18). (14) Mandible apex. Scale bar = 0.05 mm. (15) Postgenal cleft. Scale bar = 0.1 mm. (16) Hypostoma. Scale bar = 0.05 mm. (17) Thorax showing pupal gill histoblast. Scale bar = 0.5 mm. (18) Anterior proleg (modified from Davies & Györkös 1988: 109). Scale bar = 0.1 mm. (19) Pharate pupal gill. Scale bar = 0.2 mm.

FIGURES 20, 21. Protaustrosimulium pilfreyi. Last instar larva. (20) Anal sclerite & accessory sclerites (ac sl) (modified from Davies & Györkös 1988: 109). Scale bar = 0.1 mm. (21) Anal sclerite, accessory sclerites (ac sl) & circlet of hooks (Grampians). Scale bar = 0.2 mm.

FIGURES 61–66. Protaustrosimulium amphorum. Last instar larva. (61) Maxilla. Scale bar = 0.1 mm. (62) Postgenal cleft. Scale bar = 0.2 mm. (63) Hypostoma. Scale bar = 0.05 mm. (64) Thorax showing pupal gill histoblast. Scale bar = 0.5 mm. (65) Pharate pupal gill. Scale bar = 0.2 mm. (66) Anal sclerite, accessory sclerites (a s), semicircular sclerite (s s) & circlet of hooks. Scale bar = 0.2 mm.

FIGURES 54, 55. Protaustrosimulium amphorum. Pupa. (54) Thoracic cuticle. Scale bar = 0.2 mm. (55) Abdominal segment IX. Arrows indicate terminal spines. Scale bar = 0.1 mm.

FIGURES 1–6. Protaustrosimulium pilfreyi. Female adult. (Modified from Davies & Györkös 1988: 106). (1) Frontal view of head. Scale bar = 1.0 mm. (2) Hind leg. Scale bar = 0.2 mm. (3) Calcipala & tarsomere II. Scale bar = 0.05 mm. (4) Claw & basal tooth. Scale bar = 0.05 mm. (5) Genitalia (spermatheca, genital fork, hypogynial valves). Scale bar = 0.1 mm. (6) Cercus & anal lobe; lateral view. Scale bar = 0.1 mm.

FIGURES 33–38. Protaustrosimulium amphorum. Female adult. (33) Abdominal tergites. Scale bar = 0.5 mm. (34) Spermatheca. Scale bar = 0.05 mm. (35) Genital fork. (lateral apodeme – l a). Scale bar = 0.05 mm. (36) Hypogynial valves. Scale bar = 0.1 mm. (37) Cercus & anal lobe. Scale bar = 0.05 mm. Fig. 38. Protaustrosimulium amphorum. Male adult. (38) Habitus. Scale bar = 1.0 mm.