Youngomyia matogrossensis, Proença & Maia, 2019

Proença, Barbara & Maia, Valéria Cid, 2019, A new species of Youngomyia Felt from Brazil and new morphological data on Youngomyia pouteriae Maia (Insecta, Diptera, Cecidomyiidae), Revista Brasileira de Entomologia 63 (2), pp. 130-135 : 131-134

Youngomyia matogrossensis sp. nov. ( Figs. 2–18 )

Diagnosis. Adult: claws two-toothed; empodia short, not reaching bend in claws; claviform gonostylus; setulose and oval cerci; hypoproct slightly longer than cerci; aedeagus long and triangular. Ovipositor short, slightly protrusible, with 1.6 times the length of sternite 7; oval and separated cerci. Pupal exuviae: antennal bases short and triangular; prothoracic spiracle long; abdominal segments 2–8 with serrated dorsal spines. Larvae: two-toothed spatula with tapered end; three pairs of setulose terminal papillae. Description. Adult. Body length: 2.9–3.4 mm in males (n = 4), 3.9–4.6 mm in females (n = 3). Head ( Figs. 2–6 ): Frontoclypeus with 5–9 setae (n = 5); labrum long-attenuated with 2 pairs of ventral sensory setae close to the apex (n = 3), hypopharynx apically setulose, slightly longer than labrum (n = 3), labellae long, convex, setulose, with two pairs of setae (n = 3); palpus two-segmented, cylindrical, the second two times longer than the first one. Occipital process absent. Eyes facets hexagonal, closely approximated. Antenna 2 + 12: scape obconical with 2–3 setae (n = 4), pedicel globose with 2–5 setae (n = 4) ( Fig. 2 ). Male flagellomeres: distal circumfilum with loops longer than those of the others and middle circumfilum with loops shorter than those of the basal one ( Fig. 3 ). Female flagellomere 1 slightly longer than the others; circumfila in two rings slightly sinuous, one ring distal and the other subbasal, interconnected by a longitudinal slightly sinuous strand ( Fig. 4 ). Antennae with long and setulose necks and flagellomere 12 with apical process in both sexes ( Figs. 5 and 6 ). Apical process 7.0 times shorter than flagellomere 12 in males (n = 1) and 6.5 times in females (n = 1). Thorax ( Figs. 7 and 8 ): Male wings with 2.3–2.5 mm in length (n = 4), female wings 2.9–3.0 mm in length (n = 4). Rs evanescent, reaching R1 before the midlength; the other veins as in the generic characterization ( Fig. 7 ). Anepimeron with 7–10 setae. Scutum with lateral and dorsal setae, scutelum with few subapical setae. Tarsal claws robust, strongly sclerotized, bend at the basal third, two-toothed, the superior tooth conspicuously longer than the inferior one; setulose empodia, not reaching the bend in claws ( Fig. 8 ). Male abdomen ( Fig. 9 ): tergites 1–7 sclerotized, rectangular, with one anterior pair of trichoid sensilla. Tergites 1–6 with single row of posterior setae; some sparse setae irregularly distributed and scales elsewhere. Tergite 7 evenly sclerotized, with setae irregularly distributed. Tergite 8 not sclerotized with only one anterior pair of trichoid sensilla as vestiture. Sternites 2–8 sclerotized, rectangular, with one pair of trichoid sensilla, scales elsewhere. Sternites 2–4 with a simple row of posterior setae and scattered mesal setae; sternites 5–7 with more than two posterior

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rows of setae and scattered setae on the rest of the sternites. Sternite 8 reduced, about 0.10–0.12 mm in length (n = 7), with scattered setae on posterior margin, more concentrated from distal half to posterior margin. Stenite 8 about 0.45–0.65 mm as long as sternite 7. Male terminalia ( Fig. 10 ): gonocoxite oval, not splayed, covered with setae, with spiny and rounded mesobasal lobes, slightly shorter than the hypoproct; gonostylus claviform, 1.5–1.6 times shorter than gonocoxite (n = 2), with strongly pronunciated striae at all extension, delimiting elongated cells, each one with a seta at the apex; setulose at basal 1/5. Cerci oval, setulose, with apical setae; hypoproct slightly bilobated, setulose, and slightly longer than cercus; aedeagus very long, triangular, strongly sharp at the apex, with lateral pitted sensorial from the apex to middle length. Female ( Fig. 11 ): tergites 1–7 and sternites 2–7 sclerotized, with scattered scales and anterior pair of trichoid sensilla. Tergites 1–6 rectangular, with rounded margins, single row posterior setae and scattered mesal setae. Tergite 7 with setae more concentrated at the posterior margin. Tergite 8 not sclerotized, with only one anterior pair of trichoid sensilla as vestiture. Sternites 2–7 quadrangular, with scattered scales and anterior pair of trichoid sensilla. Sternites 2–5 with row of posterior setae and lateral setae. Sternite 6 with a double row of posterior setae, row of lateral setae and mesal setae. Sternite 7 with setae concentrated posteriorly, laterally and mesally. Sternite 8 not sclerotized, with only one anterior pair of trichoid sensilla as vestiture. Ovipositor ( Fig. 12 ): short, slightly protrusible, about 1.6 times as long as sternite 7; cerci oval, setulose, with dorsal setae longer than the ventral setae; hypoproct tiny, glossiform and setulose. Segment 9 with scattered setae quite varied in size, more abundant ventrally.

Pupal exuviae ( Figs. 13 and 14 ): Length: 3.2–3.9 mm (n = 5). Cephalic region ( Fig. 13 ): cephalic seta short with 0.03–0.05 mm in length (n = 9); apical plate with rough integument in all extension except apically; anterior margin with abundant short spines. Antennal bases sclerotized, triangular, smooth and short, with 0.03–0.05 mm long (n = 8). Upper and lateral cephalic margin thickened. Two pairs of lower facial papillae, one setose and one asetose; two groups of three lateral facial papillae: one pair bigger and asetose, and two setose. Thorax: prothoracic spiracle long, strongly sclerotized, triangular, bent at the 5th distal portion and slightly bent sub apically, 0.32–0.49 mm long (n = 7); outer margin serrated from the distal half. Foreleg sheath reaching the anterior margin of abdominal segment 5; midleg sheath reaching the middle of abdominal segment 5; hindleg sheath reaching the distal margin of abdominal segment 5. Abdomen ( Fig. 14 ): spiny integument. Segment 1 covered with small spines. Anterior margin of abdominal segment 2–8 with a row of irregular serrated spines of different sizes. Segments 2–8 sclerotized from the anterior margin until the end of the spiny area.

Larvae ( Figs. 15–18 ): Length: 1.1–2.7 mm (n = 13). Fusiform body, white coloration. Integument dorsal and ventrally rough. ( Figs. 15 and 16 ). Spatula strongly sclerotized, with 0.2–0.3 mm in length (n = 13), with two well developed teeth, parallel, well separated from each other, apical margin serrated between the teeth. Spatula shaft reduced in length, with about 1/4 of the spatula total length and weekly sclerotized at the end. One asetose pair of sternal papillae; two pairs of setose lateral papillae on each side of the spatula ( Fig. 17 ); four pairs of setose terminal papillae: two pairs smaller than the others ( Fig. 18 ).

Etymology. The specific name matogrossensis refers to Mato Grosso, the Brazilian state where this species was collected.

Material examined. Holotype. BRAZIL: ♂ (slide), Midwest Brazil, Mato Grosso, Parque Nacional da Chapada dos Guimarães, Caminho Véu da Noiva trail, 15 ◦ 24 l 20 ll S; 55 ◦ 49 l 47 ll W, 5 Sep. 2011, Maia, V.C. and Ascendino, S. col., Pouteria torta (Mart.) Radlk. ( Sapotaceae ), ( MNRJ).

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0.1 mm Paratypes. BRAZIL: Midwest Brazil , 12 ♂♂, 10 ♀♀, 5 pupal exuviae and 9 larvae in permanent slides, same data as holotype ( MNRJ) .

Additional Figs. 19, 20, 21, 22 and 23 showing respectively, one adult female, one larva, one young pupa, one mature pupa of Youngomyia matogrossensis and one microhymenoptera pupa (parasitoid).

Gall. The galls of Youngomyia matogrossensis are initially green, brownish when mature, and brownish-red when senescent. Brown trichomes are observed throughout the galls, being more abundant at the apex. The galls are found on young or mature leaves, on both adaxial and abaxial surfaces, being more abundant on the abaxial surface.

Host plant. Pouteria torta (Mart.) Radlk ( Sapotaceae ).

Distribution. So far, Youngomyia matogrossensis occurs in three Brazilian states: Mato Grosso, present study, Mato Grosso do Sul, in Aquidauana municipality ( Urso-Guimarães et al. (2017)) and São Paulo, in Ecological Station of Jataí ( Saito and Urso-Guimarães, 2012) and in Pé-de-Gigante Reserve, Santa Rita do Passa-Quatro ( Urso-Guimarães and Scareli-Santos, 2006). All areas in the Cerrado biome.

134 B. Proença and V.C. Maia / Revista Brasileira de Entomologia 63 (2019) 130–135

Comments. Urso-Guimarães and Scareli-Santos (2006) recorded leaf galls on Pouteria torta , in Minas Gerais State, Brazil, and suggested that they were induced by a new species of Youngomyia . Scareli-Santos et al. (2008) described the structure as well as the histochemistry of these galls. Later, the inducer was identified as Youngomyia pouteriae Maia, 2001 by Saito and Urso-Guimarães (2012). After comparing the specimens that we have obtained from Pouteria torta with the type specimens of Y. pouteriae , we realized that the former is a new species of Youngomyia . The new species was included in Youngomyia based on the following characters: necks of the flagellomeres setulose; gonocoxites with spines on the mesobasal lobes; gonostylus striated; and larvae with two-toothed spatula with tapered end.

Among the previously known species, three have elongated cerci: Y. pouteriae Maia, 2001 ; Y. podophylla (Felt, 1907) and Y. knabi (Felt, 1912) as well as the new species. However, only in Y. pouteriae and Y. matogrossensis the spines on male’s hypoproct are absent.

Despite these similarities Y. pouteriae and Y. matogrossensis differ in the following aspects: adults – two-segmented palpi in the new species ( Fig. 24 ) and one-segmented in Y. pouteriae (Fig. 25); male cercus shorter and aedeagus narrower in Y. matogrossensis ( Fig. 26 ) than those of Y. pouteriae (Fig. 27); male hypoproct slightly bilobated in the new species and simple in Y. pouteriae ; mesobasal lobes of Y. pouteriae more pronunciated than those of Y. matogrossensis . Pupal exuviae: Lateral facial papillae are present in the new species but absent in Y. pouteriae . Larval spatula without indentation at external margin of the lateral side in Y. matogrossensis ( Fig. 28 ), but this indentation is present in Y. pouteriae (Fig. 29).

This is the second Youngomyia species described from Brazil and the first from Cerrado. The previous known species, Youngomyia pouteriae Maia, 2001 , was found in Atlantic forest areas of Rio de Janeiro ( Brazil).

Figures

Figs. 2–8. Youngomyia matogrossensis Proença & Maia.(2) Male head (frontal view); (3) male flagellomere; (4) female flagellomere; (5) male flagellomere 12; (6) female flagellomere 12; (7) male wing; (8) female mid leg: claws and empodium (lateral view).

Figs. 9–12. Youngomyia matogrossensis Proença & Maia. (9) Male abdomen, segments 6–8 (lateral view); (10) male terminalia (dorsal view); (11) female abdomen, segments 6–8 (lateral view); (12) ovipositor (lateral view).

Figs. 13–18. Youngomyia matogrossensis Proença & Maia.(13) Pupa: cephalic region and prothoracic spiracle (frontal view); (14) pupa: abdominal segment 5 (dorsal/lateral view); (15) larva, general aspect (ventral view); (16) larva, general aspect photomicrograph (ventral view); (17) larval spatula (ventral view); (18) larva: terminal segment (ventral view).

Figs. 19–23. Youngomyia matogrossensis Proença & Maia. (19) Larva inside gall’s chamber; (20 and 21) young and mature pupa inside gall’s chamber; (22) undetermined hymenoptera parasitoid in the gall; (23) adult female.

Figs. 24 and 25. (24) Palpus two-segmented of Youngomyia matogrossensis Proença & Maia (black arrow); (25) palpus one-segmented of Youngomyia pouteriae Maia, 2001 (black arrow).

Figs. 26 and 27. (26) Male terminalia of Youngomyia matogrossensis Proença & Maia. (27) Male terminalia of Youngomyia pouteriae Maia, 2001. The arrows point out to the following structures: black arrow: mesobasal lobe; red arrow: cerci; green arrow: hypoproct.

Figs. 28 and 29. Larval spatula of (28) Youngomyia matogrossensis Proença & Maia; (29) Youngomyia pouteriae Maia,2001.The arrows show the difference between the larval spatula of both species. An indentation at the external margin of the teeth is only observed in Y. pouteriae.