Myrciariamyia admirabilis Maia

Maia, Valéria Cid & Fernandes, Wilson, 2007, Myrciariamyia admirabilis, a new species of gall midge (Diptera, Cecidomyiidae) associated with Erythroxylum suberosum (Erythroxylaceae), Zootaxa 1554, pp. 41-48 : 42-47

Myrciariamyia admirabilis Maia , sp.nov. (Figs. 1–17)

Adult. Body length: 2.10–2.95 mm in male (n=9); 2.80–3.45 mm in female (n=6) (Table 1).

FIGURES 1–6. Myrciariamyia admirabilis Maia , sp. nov. 1, Female head (frontal). 2, Male flagellomeres 12–16. 3, Female flagellomeres 14–18. 4, Male flagellomere 5. 5, Female flagellomere 5. 6, Female wing.

Head (Fig. 1): eye facets circular, facets wider apart laterally than elsewhere, vertex without facets. Antenna with scape obconic, pedicel globose, 16–17 flagellomeres in male; 18–20 in female; proportion of last flagellomeres as in Figs. 2 and 3; each node with two horizontal circumfila connected by two vertical strands (Figs. 4 and 5); last flagellomere elongate and longer than the preceding only in female (Fig. 3). Frontoclypeus with 8–16 setae. Labrum long-attenuate with 3 pairs of ventral sensory setae. Hypopharynx of same shape as labrum, with long, anteriorly directed lateral setulae. Labella elongate-convex, each with several lateral setae and 2 pairs of short sensory setae. Palpus with four setose segments: segment one spheroid, the others cylindrical; segment one and two subequal in length; segment three and four progressively longer.

Thorax: Anepimeron setose; other pleural sclerites asetose. Wing (Fig. 6): length: 1.55–1.90 mm in male (n=9); 1.95–2.20 mm in female (n=6). Tarsal claws bowed beyond midlength, toothed; empodium longer than bend in claws ( Fig. 7 ).

Abdomen: Male ( Fig. 8 ): tergites 1–7 rectangular, more sclerotized caudally, with complete row of caudal setae, 2 basal trichoid sensilla, and elsewhere with scales; tergite 8 completely sclerotized with only two trichoid sensilla; sternites 2–8 rectangular, more sclerotized mesally and caudally, with setae more abundant at midlength, a complete row of caudal setae, 2 basal trichoid sensilla, and elsewhere with scales. Male terminalia (Figs. 10–11): gonocoxites wide, not splayed; gonostylus about 4.5 times as long as wide; cercus oval and setose; hypoproct bilobed, about as long as cerci; parameres and hypoproct subequal in length; aedeagus tapering gradually to apex. Female ( Fig. 9 ): tergites 1–8 rectangular with complete row of caudal setae, 2 basal trichoid sensilla, and elsewhere with scales; sternites 2–7 rectangular with setae more abundant at midlength, a complete row of caudal setae, 2 basal trichoid sensilla, and elsewhere with scales; sternite 8 not sclerotized. Ovipositor short, but protrusible; cerci ovoid, separate, setose, with two trichoid setae ventroapically (Fig. 12).

FIGURES 10–14. Myrciariamyia admirabilis Maia , sp. nov. 10, Male terminalia (dorsal). 11, Male terminalia (ventral). 12, Female cerci (dorsal). 13, Pupa head (frontal). 14, Pupal prothoracic spiracle.

Pupa. Length: 2.30–2.60 mm (n=4) (Table 2). Head (Fig. 13): base of antenna short; cephalic setae 0.07– 0.11 mm in length (n=4) (Table 2); facial papillae absent; upper cephalic margin thickened laterally. Thorax: prothoracic spiracle short, 0.06–0.07 mm in length (n=4) (Fig. 14) (Table 2); wing sheath reaching distal margin of abdominal segment 3; foreleg sheath reaching to middle of abdominal segment 6; midleg sheath reaching basal ¼ of abdominal segment 7; hindleg sheath reaching basal margin of abdominal segment 8. Abdomen: segments 2–8 with many dorsal spines of different length concentrated before midlength (Fig. 15).

Larva. Body elongate, cylindrical, tapered at both ends, widest at thorax; length: 2.65 mm (n= 1). Integument rough. Spatula 0.20 mm length (n=1); with two barely distinguishable apical teeth (Fig. 16); three asetose lateral papillae per side. Terminal segment convex with two pairs of setose anal papillae and three pairs of setose terminal papillae, all similar in length (Fig. 17).

Gall. On the adaxial surface of the leaf lamina, covered by a dense mat of long trichomes of red coloration (see BIERAS & SAJO 2004).

Remarks. This is the third described species of Myrciariamyia . The larva of M. admirabilis differs from the other Myrciariamyia species in having two barely distinguishable apical teeth on the spatula; three lateral papillae on each side of the midline and the terminal segment convex (without a “tail”). In M. bivalva and M. fernandesi , the spatula has two well developed apical teeth, two groups of three lateral papillae on each side of the midline, and the terminal segment resembles a “tail”. The pupa of M. admirabilis is distinguishable due mainly to the reduced prothoracic spiracle and absence of the facial papillae, while that of M. bivalva and M. fernandesi has a long prothoracic spiracle and facial papillae are present. Adults of M. admirabilis are distinctive for having the eye facets more separated at the vertex, female with the lowest number of flagellomeres (29 in M. bivalva ; 27 in M. fernandesi and 18–20 in M. admirabilis ) and longest flagellomere necks in the genus, and male with flagellomere necks lacking setulae or striae; a wider hypoproct with a less accentuated incision, and an entirely setulose gonostylus.

FIGURES 15–17. Myrciariamyia admirabilis Maia , sp. nov. 15, Pupal abdominal spines, segment 7 (dorsal). 16, Larval spatula and associated papillae. 17, Larval terminal segment.

Type material. Holotype male. BRAZIL, Minas Gerais: Tiradentes, Serra de São José, 08.IX.1997, R. Alves col. MNRJ. Paratypes: same data as holotype, 2 males and 8 pupal exuviae; Serra do Cipó, 25.VI.1998, G. W. Fernandes col., 7 males, 7 females and 1 pupal exuviae; Tiradentes, 24.X.2001, V. Maia col., 3 males and 1 larva.

Etymology. The name admiralis refers to the aspect of the gall.

Comments. These galls are extremely conspicuous due to their appearance and color [( Figs. 18–19 ) and Fig. 28 in MAIA & FERNANDES, 2004)]. They are induced along the central leaf vein and are coalescent. A single spheroid chamber is found in each gall. As the number of galls increase the leaf may curve downwards. The host plant is popularly known in the cerrado vegetation of Brazil as “mercúrio do campo” (field mercury), perhaps owing to the red coloration of the gall or even due to the orange sap found inside the plant stems. Galls are widely used in the construction of nests of many birds including hummingbirds, and even solitary wasps (GWF, per. obs.). Yet another interesting observation is the remarkable resemblance of the galls with a generalist Lepidoptera ( Fig. 20 ). A lepidopteran specialist once mistook a gall for a caterpillar and a student once mistakenly touched a poisonous caterpillar thinking she was collecting a gall (GWF, unpublished data). Apparently similar red and hairy galls induced by cecidomyiids on congeneric hosts were reported by FERNANDES ET AL. (1988) on E. coelophlebium Mart. in Belo Horizonte ( Brazil); by FERNANDES ET AL. (1997) on E. campestre St. Hil. in the Jequitinhonha Valey ( Brazil), and by GONç ALVES-ALVIM & FERNANDES (2001) on two different Erythroxylum hosts in Três Marias ( Brazil). No adults were reared from galls on these other plants to allow identification of the gall inducing species.

Figures

FIGURES 7 – 9. Myrciariamyia admirabilis Maia, sp. nov. 7, Male, foretarsal claw and empodium. 8, Male abdominal segment 3 to end (dorsolateral). 9, Female abdominal segments 4 to end (dorsolateral).

FIGURES 18 – 19. Gall of Myrciariamyia admirabilis Maia, sp. nov. on Erythroxylum suberosum (Erythroxylaceae).

FIGURE 20. A generalist caterpillar on Erythroxylum suberosum (Erythroxylaceae).