Machaeriobia gemmae Maia, 2016

Maia, Valéria Cid, Wilson, Vinícius Abexander Condé & Monteiro, Ricardo Ferreira, 2016, A new species of Machaeriobia Rübsaamen, 1915 (Diptera, Cecidomyiidae) from Brazil, Revista Brasileira de Entomologia 60 (3), pp. 227-230 : 228-230

Machaeriobia gemmae Maia , sp. nov. ( Figs. 2–13 )

Diagnosis: Adult: palpus one or two-segmented; tarsal claws simple; male hypoproct and cercus similar in shape; cercus slightly longer than hypoproct, aedeagus deeply notched; gonocoxites with rounded mesobasal lobe, ovipositor bulbous with long, flexible lateral setae, female cerci with some sensorial setae, the tapered cerci with a few short setae. Pupa: antennal horns short, abdominal tergites 6–8 with a row of three or four spines. Larva: spatula with two widely separated teeth and reduced shaft; mamelons absent; terminal segment elongate, tapered to apex, sclerotized apically, without apparent papillae.

Adult description. Male. Body length: 3.20–4.60 mm (n = 3). Head ( Fig. 2 ): eye facets circular, closely approximated. Antenna: scape about as long as large; pedicel: 0.50–0.55 times wider than long; flagellomeres binodal, distal node constricted at middle, tricircumfilar, circumfila with loops short and regular in length, neck bare ( Fig. 3 ), flagellomere 12 with a setulose apical process. Frontoclypeus with 08–10 setae (n = 3). Mouthparts ( Fig. 4 ): palpus

0.20

slightly longer than large, with one or two segments, claviform when one-segmented, first segment globose and second claviform when two-segmented; labrum long-attenuate with one pair of ventral sensory setae; hypopharynx of same shape as labrum, with long, apically directed lateral setulae; labella hemispherical, with several lateral setae and three pairs of short mesal sensory seta. Thorax: Anepimeron with several setae, other pleural sclerites asetose. Wing: 3.60– 2.80 mm long (n = 3). Halter: 0.60 mm long (n = 3). Apical projection of first tarsomere 0.016 mm (n = 3) long. Legs missing. Abdomen: tergite 1 sclerotized only at distal half; tergites 2–7 rectangular, completely sclerotized; tergites 1–7 with a complete row of posterior setae, two anterior trichoid sensilla and elsewhere with scattered scales. Tergite 8 elliptical, with only two anterior trichoid sensilla as vestiture. Sternites 2–8 completely sclerotized, rectangular, with setae more abundant mesally, a complete row of posterior setae, and two anterior trichoid sensilla. Terminalia ( Fig. 5 ): gonocoxite about 4 times long than large, cylindrical beyond short mesobasal lobe; gonostylus about 5 times as long as wide, cylindrical; cercus setose with margin convex, slightly longer than hypoproct; hypoproct setose, similar in shape to cercus; aedeagus deeply notched at apex. Female: as for male, except for: body length: 5.60 mm (n = 1); head: antenna: scape about 2 times wider than long; pedicel: 1.4 times wider than long (n = 1); flagellomeres cylindrical with two interconnected circumfilar rings and bare neck ( Fig.6 ); twelfth flagellomere with setulose apical process. Wing: 4.13 mm long (n = 1). Halter: 0.70 mm long (n = 1). Abdomen: tergites 1–7 rectangular with a complete row of posterior setae, a row of mesal setae, two anterior trichoid sensilla and elsewhere with scattered scales; tergite 8 unsclerotized, with a pair of anterior trichoid sensilla. Sternites 2–7 rectangular with setae more abundant mesally, a complete row of posterior setae and two anterior trichoid sensilla. Sternite 8 unsclerotized. Ovipositor basally bulbous, tapered beyond with lateral setae, 1.6 times longer than sternite 7, cerci tapered to point, with a few short setae, hypoproct glabrous ( Fig. 7 ).

Pupa. Length: 2.40–2.80 mm (n = 3). Head ( Fig. 8 ) with grainy integument and short antennal horns (0.05 mm long) (n = 3); pair of cephalic setae very short (0.007 mm long) (n = 3); two pairs of lower facial papillae, one asetose, the other with short seta; three pairs of lateral facial papillae, two with short seta, the other asetose. Prothoracic spiracle relatively short (0.12 mm long), setiform ( Fig. 8 ). Abdominal tergites 6–8 each with a single row of three or four dorsal spines, other tergites without spines ( Fig. 9 ).

Larva. Body length: 3.20 mm (n = 1). Integument covered with pointed verrucae. Spatula: 0.07 mm long (n = 1), two-toothed, with very short shaft, three pairs of lateral papillae ( Figs. 10 and 11 ). Terminal segment with a tail-like projection of 0.15 mm of length (n = 1); sclerotized apically; terminal papillae not visible ( Fig. 12 )

Gall. Leaf bud gall, spherical, green or reddish, hairy, onechambered ( Fig. 13 ) on Machaerium macaense .

Type material. Holotype male. Brazil, Rio de Janeiro, Parque Nacional da Serra dos Órgãos, II.2009, Wilson and Monteiro leg., MNRJ . Paratypes, same data as holotype – 2 males, 1 female, and 1 larva; 15.XI.2013 – 2 pupae and 3 pupal exuviae. MNRJ .

Etymology. The name “ gemmae ” refers to the galled plant organ in Latin.

Comments. Machaeriobia is very similar morphologically to Anadiplosis . Adults of both genera show no essential differences ( Gagné, 1994), but according to Tavares (1920), larval characters can separate the two genera. In Machaeriobia , mamelons beneath the lateral papillae are absent and the prothoracic spatula is present, while in the species of Anadiplosis whose larvae are known, mamelons are present and the spatula is absent. Unfortunately, the larva of A. pulchra , the type-species, is still unknown. Among the family Cecidomyiidae , there are some genera whose species may or may not present a spatula, such as Baccharomyia Tavares, 1917 , Geraldesia Tavares, 1917 , Rhopalomyia Kieffer & Herbst, 1909 , and Lopesia Rübsaamen, 1908 ( Gagné, 1994; Rodrigues and Maia, 2010). We hereby synonymize Anadiplosis Tavares, 1916 under Machaeriobia Rübsaamen, 1915 based on similarities of the ovipositor, male cercus and hypoproct of both genera. Among the species previously described as Anadiplosis (hereafter referred to as Machaeriobia ), the new species is morphologically most similar to M. pulchra . The pupa of both species has short antennal horns, same complement of facial papillae, prothoracic spiracles similar in shape and length and similar number of abdominal spines.

Adults of M. pulchra have two-segmented palpi, whereas in the new species they are one or two-segmented. The ovipositor of both species is very similar ( Figs. 7 and 15 ). While there are few differences between the pupae and females of the two species, the male of M. gemmae is very different from the male of M. pulchra , especially in relation to the terminalia ( Figs. 5 and 16 ). Machaeriobia gemmae has a markedly more notched aedeagus, and longer and less curved gonostyli than those of M. pulchra . Furthermore, the mesobasal lobe of the gonocoxites is rounded in M. gemmae , and acute in M. pulchra . The larva of M. gemmae is unique among its congeners for the presence of spatula, the absence of mamelons and the shape of the terminal segment (elongate, tapered to the apex and without distal lobes).

The new species differs from Machaeriobia machaerii in the shape of the male hypoproct and cercus (both more acuminate in M. machaerii ) ( Fig. 17 ), and in the larval terminal segment which is bilobed in M. machaerii ( Fig. 18 ) and simple in the new species. From the first sample of 30 galls collected on September 2012), we obtained only M. gemmae , but from the 400 galls collected from October 2013 to January, 91 galls yielded wasps and 10 M. gemmae. The reared wasps belonged to six species: Tanaostigmodes carinatus La Salle 1987 , Tanaostigmodes sp. ( Tanaostigmatidae ), Galeopsomyia sp. ( Eulophidae ), Calorylea sp. ( Eurytomidae ) and two unidentified species of Eurytomidae .

Tanasotigmatidae include only gall inquilines, but the other families comprise gallers, parasitoids, and gall inquilines. It was not possible identify their habits as parasitoids or inquilines, but in all cases the cecidomyiid larvae died. We observed that galls attacked by some of these wasps were almost compact, with little space inside, probably due to inner tissue growth making these galls very hard and quite different from those that were not attacked. The high mortality of galling larvae caused by parasitoids or/and phytophagous modifiers has been reported in other similar communities (see Ferraz and Monteiro, 2003). We also observed that the gall development caused the death of the adjacent leaflets.

Figures

Figs. 2–7. Machaeriobia gemmae, new species. 2. Male head, frontal; 3. male flagellomere 5; 4. male, mouth parts, frontal; 5. male terminalia, dorsal; 6. female flagellomere 5; 7. ovipositor, ventral. Scales in mm.

Figs.8–12. Machaeriobia gemmae, new species.8.pupa, head and prothoracic spiracle;9.pupa,terminal segments,dorsal;10.larva,head and spatula,ventral;11.larva, spatula and lateral papillae, ventral; 12. larva, terminal segment, dorsal. Scales in mm.

Fig. 13. Gall of Machaeriobia gemmae, new species, general aspect.

Figs. 14–18. Machaeriobia spp. 14. M. pulchra, pupa, abdominal spines (redrawn from Tavares, 1920); 15. M. pulchra, ovipositor (redrawn from Tavares, 1920); 16.M. pulchra, male terminalia (redrawn fromTavares,1916); 17.M. machaerii, male terminalia (redrawn from Gagné, 1994); 18. M. machaerii, larva, terminal segment (redrawn from Gagné, 1994). Original figures without scale bar).