Corethrella (Notocorethrella) novaezealandiae Tonnoir, 1927

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 43-44

Corethrella (Notocorethrella) novaezealandiae Tonnoir

Corethrella novaezealandiae Tonnoir 1927:107 (as novae-zealandiae ). Type locality: Otira, [Westland], New Zealand. Holotype ♀ (NZAC). Belkin 1962:540, 1968:111.

Corethrella novaezelandiae: Edwards 1932:19 .

DIAGNOSIS: Male and female adults: only extant species of Corethrella with abdominal sternites 1–7 completely pigmented and tergites 1–7 mostly pale and pigmented only on their lateral margins (Fig. 76A). Also, males only extant species with each claw with inner tooth (Fig. 75A).

DESCRIPTION: Male adult. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view nearly circular (as in Fig. 6A). Two large setae on frons between ventromedial area of ommatida (as in Fig. 16A). Antenna uniformly pale or light brown; pedicel without distinctive, more elongate, stout, dorsal or dorsolateral setae; flagellomeres as in Fig. 19A, sensilla coeloconica distributed as in Table 1; flagellomere 13 without well-developed apical bifurcation. Palpus brown; segment 3 swollen apically. Thorax (as in Figs. 36A, 37A): Scutum light brown, with very anterior portion, area between prescutal and transverse sutures more darkly pigmented; scutellum dark brown; mediotergite light brown with dorsomedial portion dark brown; pleura mostly dark brown with pale transverse stripe, pale sclerites around base of wing. Posterior portion of dorsocentral row with 2 elongate setae situated somewhat lateral to one another. Prescutal suture elongate, thick, uninterrupted, extending to near dorsocentral row of setae. Anterior anepisternum divided dorsoventrally by nearly straight suture, anterior and posterior portions nearly equal in size. Ventral portion of posterior anepisternum pale, shape uncertain. Wing (Fig. 61A): Apex of R 2 distal to apex of M 1. Dark pigmentation on veins and immediately adjacent area in area from forking of R 1 +Rs posteriorly to fork of CuA, fork of R 2+3, fork of M 1+2, very apices of R 2, R 3, R, M 1, M 2, CuA 1, some with CuA 2; veins (other than wing margin) with very slender scales. Halter paler than scutellum. Legs (as in Fig. 37A): Light to medium brown with knees of fore-, midleg more pale, apical 0.7 hind femur pale but with slight darkening at apex, hind tibia pale but with slight apical darkening in some. With only slender setae, lacking scales (except for some in patch of whip-like setae on posterior portion of hind tibia). Midleg without thick, subapical setae on each of tarsomeres 1–3. Apices of fore-, midleg fifth tarsomeres undivided, with claws slightly subapical to apical (Fig. 75B). Claws of fore-, midleg longer than those of hind leg. Each claw with inner tooth. Anterior claw of each leg with basal prong. Foreleg claws equal. Midleg claws equal. Foreleg third tarsomere longer than fourth tarsomere. Empodia absent. Abdomen (Fig. 76A): Tergites 1–7 pale, only lateral margin of each dark brown. Sternites uniformly dark brown. Genitalia (Fig. 83A): Gonocoxite uniformly medium brown, parallel-sided for most of length; anteromedial area with spicules similar in length to those elsewhere on gonocoxite; without well-defined dorsal row of setae. With 5–6 stout setae grouped near apex of gonocoxite on apicomedial surface, all tapering from base, none with bases joined by sclerotized plate. Gonostylus (in retracted position) straight or slightly curved, thick, expanded to rounded apex; 1 elongate, thick subbasal seta, situated ventrally; with thick, blunt apical peg. Aedeagus slender, elongate, tapering gradually to apex, rounded apically.

4+5

Female adult. Descriptive statistics: see Tables 6–11. As for male, with following differences. Head: Coronal suture absent ( Fig. 16A). Antennal flagellomeres as in Fig. 25G, sensilla coeloconica distributed as in Table 1. Clypeus ( Fig. 17A) squarish. Mandible with small, pointed teeth. Palpus as in Fig. 33A. Wing (Fig. 66A). Legs ( Fig. 37A): as for male but some with darker pigmentation at base of hind tibia. Claws of each leg equal to those of others; equal on each leg, simple (without inner teeth). Abdomen: Cercus pale.

Immatures. Unknown.

DISTRIBUTION AND BIONOMICS: Corethrella novaezealandiae is restricted to the western portion of the South Island of New Zealand (Fig. 116B) at altitudes ranging from 33– 657 m. It is the only species of Corethrella known from that country. The two males and two females from Punakaiki were taken with a Malaise trap and two other males were collected as part of a “landing-biting” site on the shores of Lake Mapourika (Belkin 1968). Belkin (1968) suggested that the immatures likely live amongst the grassy margins of lakes and ponds but the immature stages have never been collected and this needs to be confirmed. Two females from Waiho were not seen but are included in the distribution map because they were almost certainly correctly identified by Belkin (1968).

Borkent and Szadziewski (1992) suggested an ancient ecological association between C. novaezealandiae and their proposed Leiopelma frog hosts. The two groups are now allopatric, with Leiopelma species restricted to the North Island and Cook Strait, but the South Island Leiopelma have become extinct only in the last 500 years ( Worthy 1987) and have been replaced with foreign frogs. It would be fascinating to know if C. novaezealandiae females are attracted to the calls of the males of those Leiopelma yet present on the North Island (in a laboratory setting) and whether they feed on the introduced frogs presently within their range. The males of extant Leiopelma are often said to have a weak call and appear to call irregularly ( Robb 1980) but Bell (1978) reported that male mating calls have been recorded by several workers.

TAXONOMIC DISCUSSION: Males and females were associated through the shared presence of a distinctive pigmentation pattern on the body and are members of the only species of Corethrella known from New Zealand.

Belkin (1968) provided a detailed description of the male and female of C. novaezealandiae . He mentioned that tergite 9 is “very large” but this feature did not seem exceptional to me when compared to other species of Corethrella . Tonnoir (1927) mentioned the presence of paratypes from Lake Brunner but only one has been located. Belkin (1968) mentioned two additional females from Waiho (30-I-1922, A..L. Tonnoir (NZAC)). One of these is in the BMNH (David Notton, pers. comm.) but the other, recorded by Belkin as present in NZAC, could not be located and is likely lost (T. Crosby, pers. comm.).

The sensilla coeloconica on flagellomere 1 of the female was difficult to see and I couldn’t be certain it was present in all specimens.

MATERIAL EXAMINED: Holotype, adult female on microscope slide, labeled “TYPE. Corethrella novae-zealandiae A. Tonnoir det”, “Otira N.Z. 7 Feb. 1922 A. Tonnoir”, “ N.Z. Arthropod Collection, NZAC, Private Bag 92170 AUCKLAND New Zealand ” ( NZAC) . Paratype: 1 ♀ from Lake Brunner , New Zealand, 2- II-1922, A. Tonnoir ( NZAC) . Other material: 2 ♂, 2 ♀ Punakaiki , BR, New Zealand, 29-XII-1983 – 3-I-1984 ( CNCI) ; 2 ♂ Lake Mapourika (Westland), 7-II-1964 ( USNM) .

DERIVATION OF SPECIFIC EPITHET: The name novaezealandiae clearly refers to the country of origin.