Polypedilum paranubifer Cranston, 2016

Cranston, Peter S., Martin, Jon & Spies, Martin, 2016, Cryptic species in the nuisance midge Polypedilum nubifer (Skuse) (Diptera: Chironomidae) and the status of Tripedilum Kieffer, Zootaxa 4079 (4), pp. 429-447 : 439-440

Polypedilum paranubifer Cranston sp. n.

( Figs 1D, G ; 2B, 2E, 3E)

urn:lsid:zoobank.org:act:063C158B-3D62-4A56-9F52-AD5F84204456

Type material. Holotype: Le /P ♂, AUSTRALIA: Northern Territory, Ranger Uranium mine, retention pond 2, 12°41’S 132°55'E, 31.v.1988 ( Cranston ) ( ANIC).

Paratypes: Le/P♀, as holotype, except retention pond 1, 15.v.1992; 4♂, as holotype (ANIC); 11♂, Ranger Uranium mine, Retention pond 4, light trap,. v.1988 (Wells & Suter) (ANIC, 2 to BMNH).

Other material examined: 4L, Northern Territory, Ranger Uranium mine, Retention Pond 1, 31.v.1988 (Cranston) ( ANIC).

Description as for P. nubifer , except as follows.

Adults ( Figs 1D, G , 2B ; female from pharate only). For mensural features see Table 1. Both sexes differ from P. nubifer in non-overlapping ranges of fewer setae on wing veins R and R1 and in the complete absence of setae on R4+5. Tergite VIII anteriorly appearing tapered to connection with T VII ( Fig. 1D ). Male genitalia ( Fig. 1G ) with gonocoxite weakly bulging, connected to gonostylus by pale membranous area. Dorsolateral seta present on a superior volsella otherwise similar in shape to that in P. nubifer . Gonostylus broad without bilobed apex, distally rounded. Female genitalia: gonapophysis VIII with dorsolateral lobe scarcely developed; ventrolateral lobe welldeveloped, 55 µm long, highly setose, with apical setae directed mesad ( Fig. 2B ). Cerci 100 x 100 µm, rounded rectangular.

Pupa ( Figs 2E , 3E ). Exuviae 5.4–5.8 mm long, pale with yellowish highlights and yellow-brown posterolateral comb on abdominal segment VIII. Cephalic tubercles conical, 50 µm high and 100 µm wide at base, bearing 35–45 µm long frontal seta inserted subapically on narrowed apical spine or ‘nipple’ of tubercle. Hook row on II c. 58– 64% of tergite width, with c. 44–45 hooklets. Spinule pattern apparently as in P. nubifer ( Fig. 3B ). Caudolateral ‘comb’ on VIII (( Figs 2E , 3E ) with 2–3 stronger spines, none dominant; 2–5 smaller subsidiary spines, not extending to L4 setal base. Anal lobe fringe uneven, uniserial, with 47–50 taeniae, without dorsal seta.

Larva. All measurements and ratios fall within the corresponding ranges for P. nubifer (see Table 2). Microsculpture of ventromental plates as in P. nubifer .

Notes. Adult males of P. paranubifer consistently differ from P. nubifer in the presence of a dorsolateral seta on the superior volsella. By itself, this difference could be seen as no more than population level variation, but it is accompanied by a suite of mensural differences in wing setation ( Table 1). The pupa seems identical to P. nubifer except for the smaller size and slightly different structure of the ‘comb’ on the posterolateral corner of segment VIII. The latter, however, varies even within ‘true’ P. nubifer , thus probably is unreliable for discrimination. Likewise, the larvae of P. paranubifer cannot be distinguished from those of P. nubifer on morphology. Unreared larvae from retention pond 1, although seemingly identical with those associated by rearing with P. paranubifer adults, cannot be included in the type series since one pupal exuviae clearly belonging to P. nubifer was found also from the same pond system.

Figures

FIGURE 1. Polypedilum spp., adults. A. Wing of female P. quasinubifer sp. n. B, C. Apex of fore tibia of: B. P. nubifer (Skuse), C. P. quasinubifer. D. Posterior abdomen of P. paranubifer sp. n. E – G. Male genitalia of: E. P. nubife r (left: dorsal, right: stylised ventral plus apodemes in segment IX); F. P. quasinubifer (dorsal, left side only); G. P. paranubifer (T IX dorsomedial setae, anal point, superior volsella). H. Female genitalia of P. nubifer (ventral, parts of some paired structures omitted).

FIGURE 2. Polypedilum spp. A – C. Female genitalia, gonapophysis VIII of: A. P. nubifer (Skuse); B. P. paranubifer; C. P. quasinubifer; DmL—dorsomesal lobe, VlL—ventrolateral lobe. D – F. Pupae, posterolateral corner of abdominal segment VIII (ventral) of: D. P. nubifer; E. P. paranubifer, F. P. quasinubifer; l — 4 th (posterior-most) lateral seta. Scale bars = 100 µm.

FIGURE 3. Polypedilum spp., pupae. A. Cephalic tubercles, frontal setae of P. nubifer (Skuse). B, C. Abdomen (dorsal) of: B. P. nubifer, C. P. quasinubifer sp. n. D, E. Posterolateral corner of abdominal segment VIII (ventral) of: D. P. nubifer; E. P. paranubifer sp. n.