Corethrella (Corethrella) nippon, Miyagi, 1980

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 54-56

Corethrella (Corethrella) nippon Miyagi

Corethrella nippon Miyagi 1980:16 . Replacement name for Corethrella japonica Miyagi. Lien et al.,1998.

Corethrella japonica Miyagi 1975:25 ; preoccupied by Corethrella japonica (Komyo) 1954 . Type locality: Nagasaki, Kyushu , Japan. Holotype ♀ (deposited at EIHU but lost).

DIAGNOSIS: Male and female adults: only extant Old World species of Corethrella with a plain wing (no pattern of pigmentation) (Fig. 66H), the scutum paler than the dark brown pleura ( Fig. 39A), and the base of the hind tibia without pigmentation (equal to the apex of the hind femur) ( Fig. 39A).

DESCRIPTION: Male adult. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view somewhat circular (as in Fig. 6F). Two large setae on frons between ventromedial area of ommatida (as in Fig. 16B). Antenna uniformly medium brown; pedicel without distinctive elongate, stout setae; flagellomeres as in Fig. 19F, sensilla coeloconica distributed as in Table 1; flagellomere 13 with well-developed apical bifurcation. Palpus brown; segment 3 swollen apically. Thorax (as in Fig. 39A): Scutum mostly light to medium brown, darker near scutellum; scutellum, mediotergite, most of pleura dark brown, with some mottling in some specimens, 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 diagonally by sinuous suture, dorsal portion about equal to ventral portion. Ventral portion of posterior anepisternum triangular, uniformly brown, with anterodorsal margin not thick. Wing (as in Fig. 66H): Apex of R 2 slightly distal to apex of M 1. Plain, without pattern of pigmented veins and/or scales; veins (other than costa and wing margin) with slender scales. Halter light brown, paler than scutellum. Legs (as in Fig. 39A): Light brown, with apex of foretibia and hind tibia slightly darker, basal 0.5 hind femur medium brown. With only slender setae, lacking scales (except for some in patch of whip-like setae on posterior portion of hind tibia). Midleg with thick, subapical setae on each of at least tarsomeres 1–3. Apices of fore-, midleg fifth tarsomeres undivided, with claws slightly subapical (as in Fig. 75D). Claws of fore-, midleg equal in length, longer than those of hind leg. Each claw without inner tooth. Anterior claws of each leg without a basal prong. Foreleg claws unequal. Midleg claws unequal. Foreleg third tarsomere longer than fourth tarsomere. Empodia thick. Abdomen: Tergites 1–7 with anterolateral light brown pigmentation, sternites medium brown with 4–6 somewhat darker anteriorly, segment 8 dark brown, segment 9 pale. Genitalia (Fig. 84A): Gonocoxite uniformly pale, gently tapering; anteromedial area with spicules similar in length to those elsewhere on gonocoxite; with well-defined dorsal row of setae, with setae of similar thickness as some other setae on gonocoxite except for most posterior seta thicker, with row curving posteromedially with posteriormost seta of row positioned dorsomedially. With one dorsomedial stout seta, tapering from base. Gonostylus (in retracted position) with slight concavity along posterior margin, curved subapically, thick, of more or less equal thickness for entire length, rounded apically; one elongate, thick subbasal seta, situated ventrally; with thick, blunt apical peg. Aedeagus slender, elongate, tapering gradually to apex, pointed apically, with lateral margins separate apically.

Female adult. Descriptive statistics: see Tables 6–11. As for male, with following differences. Head: Coronal suture elongate, extending ventrally past ommatida (as in Fig. 16B). Clypeus ( Fig. 17H) squarish. Antennal flagellomeres as in Fig. 26B, sensilla coeloconica distributed as in Table 1. Mandible with small, pointed teeth. Palpus as in Fig. 33H. Wing (Fig. 66H): (describe pigmentation in those that are different). Halter medium brown, somewhat paler or as dark as scutellum. Legs: Claws of each leg equal to those of others; equal on each leg, simple (without inner teeth). Abdomen: Tergites 1–7 with anterolateral light brown pigmentation, sternites medium brown with 3–5 somewhat darker anteriorly, segments 8–9 dark brown. Cercus light brown.

Immatures. Unknown (but see below).

DISTRIBUTION AND BIONOMICS: Corethrella nippon is known from southern Japan, south to the Ryukyu Islands (Fig. 115A) at altitudes ranging from near sea level to 70 m. Miyagi (1975) found this species at Koniya, Amami-Oshima, Japan and this record, although not confirmed in this study, has been included on the distribution map as it is likely correctly identified. Toma et al. (2005) recorded this species from Iriomote Island, Okinawa, Japan and examination of specimens collected from this island indicates they were correctly identified. Lien et al. (1998) reported C. nippon as common in light trap samples from Taiwan, but specimens were not examined here and are not included in the distribution map.

Specimens studied here were collected using light, Malaise and frog-call traps.

Toma et al. (2005) found female adults attracted to a series of frog-call traps, using the simultaneous calls of eight frog species, on Iriomote Island, Japan, June 12–18. Some of the attracted females were subsequently fed on a caged frog ( Rana limnocharis ). Miyagi (1974) reported female adults of this species (as Corethrella sp. ) with an unidentified blood meal containing haemoglobin in their abdomens (which was likely frog blood). Miyagi (pers. comm.) found this species to be common at a frog-call trap on Iriomote Island on May 20, 2006.

Lien et al. (1998) discovered Corethrella larvae in crab holes in Taiwan which may have been those of C. nippon but none were reared. As noted above, the identification of Taiwanese C. nippon could not be confirmed here.

TAXONOMIC DISCUSSION: Males and females were associated by Miyagi (1975) based on their similar pigmentation pattern, and were originally collected together at a light trap, as well as more recently on Okinawa Island. The paratype specimens studied here were originally on pins and were subsequently slidemounted .

Miyagi (1975) noted the type series consisted of a holotype female and four male and 23 female paratypes, indicating that, of these, one male and two females would be deposited in the USNM. The remaining types were to be deposited in the EIHU but they are not there now (I. Miyagi, pers. comm.). Further to this, the three specimens in the USNM are all females (so that no male C. nippon from the type series appears to have been preserved).

Miyagi (1975, 1980) indicated that adults have a yellowish body but the females studied here had some banding on their abdominal tergites and the scutum is distinctly more lightly pigmented than the thoracic pleura. Miyagi (1975) also illustrated the extended gonostylus of male C. nippon as slender but in the retracted position they are actually thick.

Miyagi (1975) described the mouthparts of this species and included SEMs of those of the female. One female from Ishigaki Island appeared very pale (perhaps teneral or bleached?), and had short flagellomeres 1– 4. It may represent an undescribed species but more material is needed.

Szadziewski et al. (1994) noted a specimen of Corethrella from North Korea but there are in fact two specimens from there (one male, one female) (sent by Frank French and now in the CNCI). Both are very similar to and may be conspecific with C. nippon . However, the basal 0.4 of the hindfemur of both the male and female were darkly pigmented and the flagellomeres 2–5 and palpal segment 3 of the female were proportionally longer than in C. nippon . The specimens were collected from Paeksong-ri, 39° 25' 32 N, 126° 32' 57 E, 15-VI-1981 and Myohyang Range, 22-VI-1981 respectively .

Seven females of a species similar to C. nippon were collected on a tributary of Sungai Belalong in the Temburong district of Brunei Darussalam, Brunei (115° 09'E, 4° 33'N, 50 meters, 7-VIII-2006, U. Grafe; 6 ♀, CNCI; 1 ♀ to collector) using a frog-call trap broadcasting the call of Hyla gratiosa . The darker pigmentation of the pleura was restricted to a band extending from the antepronotum to the anterior portion of the anepimeron and the hind tibia was entirely pale. It almost certainly represents an undescribed species .

Three females of another undescribed species from Brunei collected from the site described above, but on 22-VII-2006, were also similar to C. nippon but had a midlength wing band. They were collected from a calling Megophrys nasuta (Schlegel) at 8:30 PM. A photograph by U. Grafe shows numerous identical looking female Corethrella on and surrounding the frog: seven were on the legs, two were on the back, and at least 10 were on nearby substrate (2 ♀, CNCI; 1 ♀ to collector).

MATERIAL EXAMINED: Paratypes: 1 ♀, Nagasaki, Japan, 9-VI-1973 ( USNM) ; 1 ♀, from previous locality but 5-VII-1973 ( USNM) ; 1 ♀, Amamioshima , Japan, 20-30-VII-1973 ( USNM) . Other material: 2 ♀, Banna , Ishigaki Island, Ryukyu Islands, Japan, 70 m, 22-23-V-1964 ( BPBM) ; 2 ♀, Mikyo , Tokunoshima, Amami Group, Japan, 26-VII-1963 ( BPBM) ; 9 ♀, Fukari , Iriomote Is., Japan, 2-VIII-2005 (6 ♀, CNCI; 3 ♀ USNM) ; 34 ♀ (pinned), Komi , Iriomote Is., Japan, 20-V-2006 ( CNCI) ; 3 ♂, (6 ♂, 28 ♀, pinned), Yona , Kunigami, Okinawa Is., Japan, 14-VII-2006 ( CNCI) .

DERIVATION OF SPECIFIC EPITHET: The name nippon refers to the type material’s country of origin.