Forcipomyia (Metaforcipomyia) pluvialis Malloch

Spinelli, Gustavo R., Marino, Pablo I. & Borkent, Art, 2012, A revision of Biting Midges of the Subgenera Forcipomyia (Metaforcipomyia) and F. (Saliohelea) from Costa Rica (Diptera: Ceratopogonidae), Zootaxa 3419, pp. 1-52 : 4-7

Forcipomyia (Metaforcipomyia) pluvialis Malloch

( Figs. 1–10 , 138 )

Forcipomyia pluvialis Malloch, 1923: 5 (male, female; USA, Maryland).

Forcipomyia (Forcipomyia) pluvialis: Johannsen, 1943: 778 (in list of species); Wirth, 1951: 314 (description; fig. male genitalia).

Forcipomyia (Metaforcipomyia) pluvialis: Wirth, 1965: 125 (North American catalog); Borkent & Wirth, 1997: 42 (in catalog of world species); Marino & Spinelli, 2003: 22 (in key); Grogan & Sigrist, 2007: 536 (description; distribution; figs. male, female).

Diagnosis. Male: only species of Neotropical Forcipomyia (Metaforcipomyia) with labrum truncate apically with a row of transverse elongate spicules, parameres absent and aedeagus abruptly tapering to slender prong. Female: only species of Neotropical Forcipomyia (Metaforcipomyia) with labrum truncate apically with a row of transverse elongate spicules, flagellomeres 1–8 vasiform, 9–13 elongate, spermathecae with slender, long necks.

Redescription. Male. Head. Yellowish brown. Eyes broadly abutting medially for length of three ommatidia. Antenna ( Fig. 1 ) with plume setae well-developed, flagellomeres 2–4 spherical, flagellomere 10 1.44–1.65 (1.54, n = 14) X longer than flagellomere 11, flagellomeres 10–13 elongate; flagellomere 13 with apical nipple not constricted basally; AR 0.90–1.33 (0.98, n = 14). Palpus ( Fig. 2 ) pale brown; segment 3 slender, with irregular, shallow sensory pit opening at midlength; PR 2.50–3.50 (3.07, n = 15). Labrum ( Fig. 3 ) truncate apically with elongate spicules.

Thorax. Pigmentation of scutum variable: pale, with patch of darker pigmentation anteriorly, more extensively partially pigmented or entirely darkly pigmented; scutellum, postscutellum brown; scutellum with 8 strong setae. Legs ( Fig. 4 ) pale brown except basal 0.3 of hind femur darkly pigmented, apex of hind tibia with 6 spines, tarsomeres with pectinate scales, tarsomere 1 of foreleg with two rows of 6–7 spine-like bristles, tarsomere 1 of hind leg with patch of thick setae on basal half; foreleg TR 1.71–2.00 (1.85, n = 15), midleg TR 0.82–1.05 (0.95, n = 14), hind leg TR 0.90–1.09 (1.00, n = 15); claws curved, moderately stout. Wing ( Fig. 5 ) plain, without pattern of pigmented membrane; M2 not visible; intercalary vein forked; first radial cell reduced, second well developed; fork of cubitus situated distad to level of apex of costa; wing length 0.66–1.24 (0.81, n = 14) mm; breadth 0.22–0.40 (0.28, n = 15) mm; CR 0.35–0.41 (0.36, n = 14). Halter whitish.

Abdomen. Tergites yellowish brown, most specimens with blackish lateral spots. Genitalia ( Fig. 6 ): Brown except gonostyli pale. Tergite 9 short, extending to ¼ length of gonocoxite; posterior margin truncate; cercus somewhat triangular, not extending beyond midlength of gonocoxite; sternite 9 broad, posterior margin slightly excavated. Gonocoxite slender, 2.4 X longer than greatest breadth; gonostylus 0.8 length of gonocoxite, nearly straight, tip pointed. Parameres absent, gonocoxal apodemes slightly curved. Aedeagus stout, triangular; basal arch extending to 1/5 of total length; lateral margins heavily sclerotized, abruptly tapering to slender prong, tip pointed.

Female. As for male, with following differences; antenna pale brown with flagellomeres 1–8 vasiform, longer than broad; flagellomeres 9–13 elongate, proportions as shown in Fig. 7 ; AR 0.79–0.96 (0.86, n = 9). Palpus ( Fig. 8 ) pale; third segment slightly swollen proximally with irregular, shallow sensory pit opening at midlength; segments 4, 5 completely fused, slightly shorter than segment 3; PR 2.11–3.09 (2.57, n = 12).

Thorax. Legs with tibiae with, at most, dark pigmentation on apex; apex of fore tibia with slender or stout thick spines; foreleg TR 1.60–1.92 (1.73, n = 12), midleg TR 0.80–1.05 (0.96, n = 11), hind leg TR 0.95–1.29 (1.09, n = 11), claws curved. Wing ( Fig. 9 ) plain, without pattern of pigmented membrane; first radial cell reduced; second radial cell narrow; fork of cubitus situated distad to level of apex of costa; wing length 0.66–1.22 (0.86, n = 12) mm; breadth 0.25–0.44 (0.33, n = 12) mm; CR 0.35–0.39 (0.37, n = 12).

Abdomen. Tergites yellowish brown with blackish lateral spots; segments 8–10 brown. Genital sclerotization difficult to see. Two spermathecae ( Fig. 10 ) ovoid to spherical, lightly sclerotized, with slender, long necks, slightly unequal in size, measuring 0.044 by 0.038 mm, neck 0.008 mm, and 0.040 by 0.034 mm, neck 0.006 mm. Cercus brown.

Distribution. This species in known in North America from Ontario south to Louisiana and Florida, Central America, and Brazil. In Costa Rica they have been collected from sea level to 3100 m ( Fig. 138 ).

Taxonomic discussion. Males and females were collected at the same locality and date. Forcipomyia pluvialis is similar to F. rivalis and F. truncata in sharing the apically truncated labrum. Characters to distinguish these species may be found in the key.

The pigmentation and some other morphological features of the North American material we examined was rather variable and initially suggested to us that more than one species was present. However, we were unable to find consistent differences in our rather limited material. We found the male thorax varied from having just the anterior portion darkly pigmented, to more extensively but only partially pigmented, to completely brown. Some males had the dorsal portion of the pleuron pale but those from New Brunswick and Quebec were completely dark brown. Some males had more slender gonostyli than others. The male abdomen was either nearly completely brown or with only a lateral dark patch on each side of each of tergites 2–8. Some females had thoraces with an entirely pale scutum but others had the anteromedial portion of the scutum more darkly pigmented.

In Costa Rican specimens we observed a striking degree of variation in the pigmentation patterns of male flagellomeres and scutum. The males from Guanacaste have some basal flagellomeres dark, but the one male from Chirripó has all basal flagellomeres pale. The pigmentation pattern of the thorax ranged from a completely pale scutum, to a patch of darker pigmentation anteriorly, more extensively but still partially pigmented or entirely darkly pigmented. The development of thick spines on the apex of the female foretibiae varies, with those from Tapantí having slender spines while those from Guanacaste are stout. Finally, the shape of flagellomere 2 of both males and females, and the tarsal ratio of the hind leg (0.90–1.12) are also quite variable. Specimens from Costa Rica have relatively short necks on the spermathecae compared to those from the Nearctic. We attempted to distinguish between two or more species amongst all this variation but were unsuccessful. More specimens and further study is clearly warranted.

The male holotype of F. pluvialis is in excellent condition but shrivelled. The dorsum of the thorax is pale except for an anteromedial patch of pigmentation; otherwise only the pleura and ventrum are dark brown. The leg pigmentation is difficult to discern because of shrivelling but likely is as described above (knees pale). The abdomen had the posterolateral margins of tergites 2–8 darkly pigmented, as is the case in most other specimens.

Grogan & Sigrist (2007) note that the legs of F. pluvialis are light brown but we found that the apices of the femora and base of the tibiae to be pale and more extensively so on the hind leg with about the apical 0.3 of the hind femur and basal half or more of the hind tibia pale (original material examined).

Type (examined). Holotype male on a pin, labeled “Glen Echo, Md, Aug. 14, 1921 ", “J.R. Malloch collector”, “ type no. U.S. N.M.”, “ Forcipomyia pluvialis J.R. Malloch det. Type ” (USNM).

Costa Rican specimens examined (1 male, 2 females in MLPA; 4 males, 6 females in CNCI; and 31 males, 18 females in INBC). Heredia, Pto. Viejo de Sarapiquí, La Selva Biol. Sta., 7-V-1989, B. V. Brown, CD 1260, 1 male (INBC). 2 km E Sta. Elena, 26-VIII-1993, A. Borkent, CD 1559, 1 male (CNCI). Manuel Antonio NP, 17-XI-1993, A. Borkent, CD 1672, 1 female (CNCI). Brasilito, 26-XI-1993, A. Borkent, CD 1681, 2 females (CNCI). Atenas, 29-XI-1993, A. Borkent, CD 1689, 1 male (CNCI). Same data except 2-XII-1993, CD 1690, 5 males, 4 females (INBC). 8 km SE Orosí, Tapantí NP, 12-XII-1999, Picado – Borkent, CD 5039, 1 male (INBC). Cartago prov., ACLA-P., Paraíso, Tapantí NP, Sect. La Represa, Torre ICE entre ríos Porras y Villegas, 1800 m, V-1997, R. Delgado, CD 5185, 3 females (INBC). Same data except VI-1997, CD 5338, 5 females (INBC). Same data except V- 1998, CD 5351, 2 females (INBC). Cartago prov., ACLA-P, Tapantí, Tapantí NP, La Represa, Torre ICE entre ríos Porras y Villegas, 1800 m, VI-1998, R. Delgado, Malaise tp., CD 5165, 1 female (CNCI). Guanacaste prov., Palo Verde NP, extremo E del campo de Aterrizaje, 50 m, 18-V-1999, I. Jiménez, red de golpe, CD 5104, 2 males (INBC). Guanacaste prov., ACT Bagaces, Palo Verde NP, 500 NW Estación, 50 m, 14-V/ 4-VI-1999, I. Jiménez, Malaise tp., CD 5178, 1 male (INBC). Guanacaste prov., Sector San Ramón, 4.75 km WSW de Dos Ríos de Upala, 860 m, 23-I/ 18-III-1996, A. Quesada, Malaise tp., CD 5266, 1 male (INBC). Guanacaste prov., Est. Pitilla, 9 km S. Santa Cecilia, 700 m, 29-I/ 25-II-1996, J. S. Noyes, Malaise tp., CD 5268, 1 male (INBC). Guanacaste prov., Sector La Cruz, NP Santa Rosa, Sector Murciélago, 5 km ENE Cerro Guachipelin, 40 m, 25/ 27-VII-1996, M. Araya, Malaise tp., CD 5269, 1 male, 2 females (MLPA). Guanacaste prov., Sector Murciélago, 5.5 km ENE Cerro Guachipelin, 27-VII/ 27-VIII-1996, M. Araya, Malaise tp., CD 5279, 2 males, 1 female (CNCI). Guanacaste prov., Est. Cacao, 1050-1100 m, 26-I/ 4-II-1996, J. S. Noyes, Malaise tp., CD 5272, 3 males (INBC). Same data except 6/ 28- II-1996, CD 5273, 2 males (INBC). Same data except 7/ 20-II-1996, CD 5327, 8 males, 2 females (INBC). Guanacaste prov., Macizo Miravalles, Est. Cabro Muco, 1100 m, 24-IX / 5-X-2003, B. Hernández, Malaise tp., 1 female (INBC). Limón prov., Est. Hitoy Cerere, 560 m, 12-VII-1998, E. Rojas, CD 5077, 3 males, 1 female (INBC). Limón prov., Est. Biol. Hitoy Cerere, Send. Toma de Agua, 100 m, 17-IV / 8-V-1999, F. Umaña, Malaise tp., CD 5090, 1 male (INBC). Limón prov., PILA., V. del Silencio, Send. Ref. Hoffman, 2453 m, 20-IX / 5-X-2003, Rubí, González, Delgado & Alfaro, Malaise tp., 1 female (CNCI). San José prov., Madre Selva, Fca. Los Lagos, 2000- 2600 m, IX/ X-1995, M. M. Chavarría, CD 5046, 1 male (INBC). San José prov., Chirripó NP, Sabana los Leones, 3100 m, 16-IX-1999, A. Picado, CD 5074, 1 male (INBC).

North American material examined (6 males, 3 females in CNCI; and 3 males, 2 females in W.L. Grogan collection). Canada, Quebec, nr. Rowanton, 29-VII-1954, J.A. Downes, JAD 126/2/78, 1 male (CNCI). Same data except, 3-VIII-1954, JAD 133/1/2, 1 female (CNCI). Canada, New Brunswick, Kouchibouguac NP, 13-VII-1978, J.A. Downes, JAD 12215/9/12, 2 males (CNCI). Canada, Ontario, Kemptville, 5-VI-1960, W.W. Wirth, 1 male (CNCI). USA, Maryland, Georges Co. Patuxent Wildlife Refuge, 22-VII-1978, W.W. Wirth, Malaise tp., 1 male (CNCI). Same data except 19-V-1979, 1 male (CNCI). Same data except 21-III-1978, 1 female (CNCI). USA, Maryland, Georges Co. Patuxent Wildlife Refuge, 30-VI-1979, W.W. Wirth, Malaise tp., 1 female (CNCI). USA, Maryland, Wicomico Co., Wango pitcher plant bog on TNC prop. S. junct. of Fooks Rd and Twilleys Bridge Rd, 12/ 19- VII-2004, W.L. Grogan, Malaise tp., 1 female (Grogan collection). Same data except 26-VII / 2-VIII-2004, 1 female (Grogan collection). Same data except 11-17-2004, 1 male (Grogan collection). USA, Maryland, Wicomico Co., Wango Nassawango Creek at Waste Gate Road, 8/ 15-VIII-2006, W.L. Grogan, Malaise tp., 1 male (Grogan collection). USA, Virginia, Falls Church, Holmes Run, 17-VI-1960, W.W. Wirth, light tp., 1 male (Grogan collection).

Figures

FIGURES 1 – 10. Forcipomyia (Metaforcipomyia) pluvialis Malloch. 1 – 6, male, 7 – 10, female. 1, 7 — flagellum; 2, 8 — palpus; 3 — labrum; 4 — legs; 5, 9 — wing; 6 — genitalia (ventral view); 10 — spermathecae.

FIGURES 138 – 139. Distribution map of species of Forcipomyia (Metaforcipomyia).