Trichagalma formosana, Melika & Tang, 2010

Melika, George, Pujade-Villar, Juli, Abe, Yoshihisa, Tang, Chang-Ti, Nicholls, James, Wachi, Nakatada, Ide, Tatsuya, Yang, Man-Miao, Pénzes, Zsolt, Csóka, György & Stone, Graham N., 2010, 2470, Zootaxa 2470, pp. 1-79 : 11-13

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Trichagalma formosana, Melika & Tang

new species

Trichagalma formosana, Melika & Tang , new species

Figs 31–35, 36–42, 43–47.

Type material. HOLOTYPE female: TAIWAN, Nantou Co., Cingjing Farm, Renai Township, ex Quercus variabilis , leg. Chang-Ti Tang , 2008.XI.7. adult em. 2008.XII.7. Eight PARATYPE females: 1 female: TAI- WAN, Taichung County, 36,5 K Central Cross Island Road, Kukuan , Heping Township , ex Quercus variabilis , leg. Chui-Mei Wang, 1. III. 2001. Seven female paratypes : TAIWAN, Taichung Co., 29K Central Cross Island Road, Heping Township , ex Quercus variabilis , leg. Chang-Ti Tang, 2009.XI.19. adult dissected from galls on 2009.XII.22. The holotype female is deposited in NMNS , 3 paratypes in NCHU ; 2 paratypes in USNM ; 3 paratypes in PDL.

Etymology. The species is named after Formosa, a previous name for the island of Taiwan.

Diagnosis. Closely related to Trichagalma serratae . In T. formosana , new species, the body is brown with darker brown marks; the clypeus is coriaceous, brown, with a median incision ventrally; the scape, pedicel and F1 – F2 brown, remaining flagellomeres dark brown; the head in anterior view is ovate, the broadest part of genae behind eyes is level with the transfacial line; the mesosoma in lateral view much higher; the forewing margin with very short dense cilia; the radial cell of the forewing 3.5 – 3.9 times as long as broad, R1 on a short distance running along the wing margin, while in T. serratae the body is rusty brown with black marks; the clypeus is uniformly microreticulate, black, without median incision ventrally ( Fig. 24); the antenna entirely and uniformly black ( Fig. 25); the head in anterior view is more trapezoid, the broadest part of genae behind eyes is above the level of transfacial line ( Fig. 24); the mesosoma in lateral view shorter ( Fig. 27); the smoky spots on forewing much darker and well-marked; the forewing margin with long cilia, the radial cell 4.3 – 4.5 times as long as broad, R1 reaching wing margin ( Fig. 28).

Description. ASEXUAL FEMALE (holotype). Body, legs uniformly brown; head posteriorly, antenna (except scape, pedicel, F1 – F2), mandibles, stripes along anterior parallel and parapsidal lines, scutellar foveae, preaxilla, lateral axillar area, axillula, metascutellum, central propodeal area dark brown to black; body with dense white setae; wing veins dark brown, with dark brown spots.

Head coriaceous, with uniformly very dense white setae, 2.5 times as broad as long from above; 1.4 times as broad as high in anterior view and equal to width of mesosoma. Gena coriaceous, strongly broadened behind eye, broader than cross diameter of eye. Malar space coriaceous, with dense setae, 0.4 times as long as height of eye, without striae and malar sulcus. POL 1.2 times as long as OOL; OOL 3.3 times as long as diameter of lateral ocellus, 2.0 times as long as LOL; lateral ocelli slightly ovate, larger than median rounded ocellus. Transfacial distance 1.4 times as long as height of eye and 1.8 times as long as height of lower face (distance between antennal rim and ventral margin of clypeus); diameter of antennal socket slightly shorter than distance between them, distance between socket and eye margin 1.5 times as long as diameter of socket. Lower face coriaceous, with strongly elevated median area and dense setae. Clypeus rectangular, flat, above 2.0 times as broad as high, coriaceous, with deep anterior tentorial pits, distinct epistomal sulcus and clypeopleurostomal line; ventrally emarginate and slightly incised medially. Frons coriaceous, with deep smooth and shiny impression below median ocellus; vertex and occiput uniformly dull coriaceous; interocellar area elevated. Postocciput around occipital foramen impressed, with numerous striae extending to level of gula; posterior tentorial pits large, deep, elongate; hypostomal bridge at least 2.0 times as high as broad, lower part narrowed down to emarginate hypostomal carina; occipital foramen slightly shorter than height of hypostomal bridge, around 1.5 times shorter than height of oral foramen. Antenna with 12 flagellomeres (or 13, indistinct suture between F13 and F12 visible in the paratype), longer than head+mesosoma; pedicel nearly as long as broad, F1 4.1 times as long as pedicel, 1.3 times as long as F2, F2 1.1 times as long as F3, F4 slightly shorter than F3, F6 – F11 shorter than F5 and nearly equal in length; fused F12+F13 1.7 times as long as F11; placodeal sensilla on F3–F12, in numerous rows, absent on F1–F2.

Mesosoma longer than high in lateral view, with uniform dense white setae. Pronotum uniformly coriaceous; with uniform dense white setae and irregular wrinkles, emarginate along lateral edge, followed by deep longitudinal invagination. Anterior rim of pronotum narrow, emarginate; propleuron with black stripe along lateral side, delicately coriaceous, with white setae, strongly concave in mediocentral part. Mesoscutum coriaceous, with distinct punctures in anterior 1/3; longer than broad (width measured across basis of tegulae); notauli complete, superficially impressed for full length; median mesoscutal line absent; anterior parallel and parapsidal lines not impressed, broad, smooth and shiny, extending to half of mesoscutum length, marked with black stripes. Transscutal articulation absent. Mesoscutellum slightly longer than broad, 1.5 times shorter than length of mesoscutum, uniformly coriaceous, overhanging metanotum; without distinct scutellar foveae, only transverse, slightly impressed area indicated by much darker colour present. Mesopleuron, including speculum, delicately coriaceous, shiny, with dense white setae, narrowly impressed along posterior edge; mesopleural triangle rugose, with dense white setae and numerous strong wrinkles. Metapleural sulcus reaching mesopleuron at half height; preaxilla coriaceous; lateral axillar area with parallel wrinkles, without setae; axillar carina broad, with longitudinal striae; axillula slightly ovate, smooth, with dense white setae and punctures; subaxillular bar narrow, smooth, shiny, in most posterior end narrower than height of metanotal trough. Metascutellum black, uniformly delicately punctate, slightly higher than height of smooth, shiny ventral impressed area; metanotal trough smooth, shiny, without setae. Lateral propodeal carinae absent, central propodeal area smooth, shiny, with central longitudinal delicate carina, delimited only by darker colour, without setae; lateral propodeal area uniformly coriaceous, with dense white setae; nucha very short, with few delicate longitudinal sulci dorsolaterally and laterally. Forewing longer than body, with dark brown veins and with dark irregular sclerotized pigmented spots, margin with very short dense cilia; radial cell 3.9 times as long as broad, R1 on a short distance running along wing margin, Rs nearly reaching wing margin; areolet large, triangular, well-delimited by distinct veins; projection of Rs+M reaching basalis in the lower third. Hind tarsomere I to V ratio as 1.0:0.6:0.3:0.1:0.5. Tarsal claws simple, without basal lobe.

Metasoma shorter than head+mesosoma (in fresh alive specimens metasoma longer than head+mesosoma), higher than long in lateral view, smooth, shiny, without setae; only 2nd and 3rd metasomal tergites posterolaterally with white setae; 2nd tergite extending to 1/3 length of metasoma; prominent part of ventral spine of hypopygium extremely short, as long as broad ventrally, with dense long white setae, extending far beyond apex of spine; setae located only on both lateral sides of ventral spine, absent ventrally.

Body length 4.5 – 4.7 mm (n=4). In freshly killed specimens body length 5.1-5.3 mm (n=2).

Gall. The gall when young is juicy, soft, covered with small raised tubercles, and green with purple spots on areas exposed to direct sunlight ( Figs 43, 45). The gall when mature reaches 15 mm in diameter, and is brown with a slightly irregular surface ( Figs 44, 47). The mature gall is hollow, with a tough woody wall 1.5– 2.5 mm thick. The interior space contains a single larval chamber, attached to the wall by a stalk, which, however, dry out when the gall is mature ( Fig. 46). The larval chamber is ovoid, up to 6 mm in length, and has a tough but thin wall. Galls may be found singly or in groups, most commonly on lateral buds of young shoots. Solitary galls are almost spherical, while closely clustered galls may be deformed. Old galls persist on the host tree.

Biology. Only the asexual generation is known from galls on Quercus variabilis and Q. acutissima . Galls appear on the tree from early August. Under the laboratory conditions, adults emerged in December, in the nature they might overwinter in the gall and emerge in spring of the following year. Galls mostly remains on the tree for one year. Common, however, the infestation by inquilines and parasitoids is quite high what is strongly influence the emerging of the cynipid gall inducer wasps.

Distribution. Taiwan (Taoyuan County, Fuhsing Township; Hsinchu County, Hsinfong Township and Jiashih Township; Taichung County, Central Cross Island Road, Heping Township; Nantou County, Renai Township). Same type of galls were found in Japan, and it is illustrated in Yukawa & Masuda (1996) under C – 076. However, adults were never reared in Japan and thus the species was not described.


National Museum of Natural Science


National Chung Hsing University


Smithsonian Institution, National Museum of Natural History