Diadiplosis saccharum, Urso-Guimarães & Cruz & Martinelli & Peronti, 2020

Urso-Guimarães, Maria Virgínia, Cruz, Maiara Alexandre, Martinelli, Nilza Maria & Peronti, Ana Lúcia Gonzalez Benfatti, 2020, Description of a new species of cecidomyiid (Diptera: Cecidomyiidae) predator of mealybugs (Hemiptera: Pseudococcidae) on sugarcane, Papéis Avulsos de Zoologia (Pap. Avulsos Zool., S. Paulo) 60, pp. 1-6 : 3-4

publication ID	https://doi.org/ 10.11606/1807-0205/2020.60.41
publication LSID	lsid:zoobank.org:pub:57774D2F-9059-48E6-878C-077946E5B204
DOI	https://doi.org/10.5281/zenodo.4615310
persistent identifier	https://treatment.plazi.org/id/AF6A856B-F54B-FFD5-FF2F-98B2E3A6FB77
treatment provided by	Carolina
scientific name	Diadiplosis saccharum
status	sp. nov.

Treatment

Diadiplosis saccharum sp. nov. Urso-Guimarães ( Figs. 1-3 View Figure 1 View Figure 2 View Figure 3 )

Description: Adult ( Figs. 1-2 View Figure 1 View Figure 2 ): Body length: male, 1.49-1.65 mm (N = 2); female, 1.04-1.89 mm (N = 2). Head ( Fig. 1A View Figure 1 ): Antennae with scape obconic, 5-6 setae, pedicel globose 3-4 setae. Antennal length: male 0.9-1.05 mm (N = 2), and female, 0.9-0.95 mm (N = 2). Male flagellomeres binodal, circumfila with three loops similar in length ( Fig. 1B View Figure 1 ). Male flagellomere 3 length 0.08-0.09 mm; internode length 0.01 mm, width 0.012; neck length 0.016 -0.017 mm, width 0.013 mm (N = 2). Female flagellomeres cylindrical, circumfila as in Fig. 1C View Figure 1 , flagellomere 3 length 1.0 mm; neck length 0.018 mm, width 0.2 mm (N = 2). Flagellomeres 1 and 2 not connate. Male and female flagellomere 12 with a short apical process. Frontoclypeus with approximately 15 setae (N = 4). Labrum long and tapering, with two pairs of ventral setae. Hypopharynx shape similar to labrum, with long, anteriorly directed lateral setulae. Labella round, convex, each with three lateral setae and one mesal setae. Palpus four-segmented, the first globose and the other three cylindrical; second and third segments with equal length, the fourth 1.5 longer than second and third; all setose ( Fig. 1D View Figure 1 ). Thorax: Scutum dark brown with a row of dorsocentral and lateral setae, scutellum light brown with scattered setae, anepimeron setose, other pleural sclerites asetose. Legs: Tarsal claws with a small tooth in all legs, empodium rudimentary ( Fig. 1E View Figure 1 ). Wing: Wing length: 0.15 mm in male; 0.17 mm in female (n = 2); R1 joining C at about wing midlength, CuA forked. ( Fig. 1F View Figure 1 ).

Abdomen: Male ( Fig. 2A View Figure 2 ): tergites 1-7 rectangular with a complete row of caudal setae, some lateral setae, two basal trichoid sensillae, and scattered scales.Tergite 8 unsclerotized with a row of caudal setae, trichoid sensillae and scales absent. Sternites 2-7 strap like sclerites with setae more abundant mesally, a complete row of caudal setae, some lateral setae and 2 basal trichoid sensilla,and scattered scales. Sternite 8 less sclerotized than preceding sclerites, setae, trichoid sensilla, and scales absent. Female ( Fig. 2C View Figure 2 ): tergites and sternites as in male, except for tergites and sternites 1-7 wider than in male and tergite and sternite 8 unsclerotized with a row of setae each, trichoid sensillae and scales absent. Male terminalia ( Fig. 2B View Figure 2 ): gonocoxites oblong, with dorso-lateral distal margin surpassing the insertion of gonostylus,setae concentrated at apex; gonostylus rectangular, stout, length 0.056 -0.061 mm, width 0.024 -0.027 mm (N = 2), with scattered setae, and setulae covering all gonostylus; aedeagus very long (1.2 times longer than hypoproct and 1.7 times longer than cercus); hypoproct bilobed, round, with a single long seta on each lobe and a row of setae longitudinally in each lobe; cercus fused at base, deeply bilobed, round, covered by setae. Ovipositor: tergite 10 with a pair of long and strong setae, with lesser ones; cerci elongate-ovoid as shown in Fig. 2 View Figure 2 D-2E 0.15 mm long (N = 2).

Holotype: Male: BRAZIL, São Paulo: Jaboticabal (21°18.00′34.70″S, 48°19.39′25.92″W, 605 m), col. 10.iv.2017, Cruz, M.A. col., Urso-Guimarães, M. V. det. Slide mounted deposited in MZSP . Paratypes: Same data of holotype, except for: 8 ♂; 4 ♀, Cruz, M.A. col., Urso-Guimarães, M. V. det .; 1 specimen, BRAZIL, State of São Paulo: São Carlos (22°04′33.87″S, 47°48′37.59″W, 11.v. 2017, 856 m a.s.l.), Cruz, M.A. col., Urso-Guimarães, M. V. det. Slide mounted deposited in MZSP GoogleMaps .

Etymology: The name saccharum is based on the name of the sugarcane genus (Saccharum), cultivar in which the specimens of the new species was found prey on nymphs of Saccharicoccus sacchari .

Biology: Adults of Diadiplosis saccharum sp. nov. were reared from leaf sheaths on stem nodes of sugarcane (Saccharum spp.) with larvae of cecidomyiids preying on nymphs of of Saccharicoccus sacchari ( Fig. 3 View Figure 3 ), which is a potential pest for Poaceae plant species, since sugarcane producers have reported frequent infestations in Brazil ( Cruz et al., 2019).

Remarks: Despite the new species resemble the Neotropical Diadiplosis , D. bellingeri , D. martinsensis and D. aleyrodici (Felt, 1922) , with the eyes undivided, palp 4-segmented, tarsal claws toothed at base or not (except in D. martinsensis ), cercus and hypoproct bilobed, Diadiplosis saccharum sp. nov. differ from all known species based mainly on the combination of the characters of male terminalia ( Fig. 2B View Figure 2 ): gonocoxite oblong with the dorso-lateral distal margin surpassing the insertion of gonostyli, gonostylus rectangular and stout. The new species and D. pseudococci have prolongation of the dorso-lateral distal margin of gonocoxite after the insertion of gonostyle, but in this species, the prolongation is larger and shorter than in D. pseudococci ( Fig. 4E View Figure 4 ). A long and triangular aedeagus is shared with D. bellingeri and D. martinsensis , but in the first, the hypoproct is deeper bilobed ( Fig. 4G View Figure 4 ) than in the new species, and in the latter the aedeagus is smaller than hypoproct and cercus ( Fig. 4F View Figure 4 ). The male terminalia of D. saccharum resembles the general shape of the D. abacaxii terminalia by the sclerotization, but they differ greatly in aedeagus, bulbous in D. abacaxii and regular in D. saccharum . In addition, they also differ in the number of segments of palpi, three in D. abacaxii and four in D. saccharum .

This is the first register of a cecidomyiid larvae preying on an insect pest on Saccharum spp. ( Poaceae ) – a major agricultural commodity in the tropics and used mainly for making sugar and ethanol for fuel. Saccharicoccus sacchari can be classified as an emergent pest in Brazil, since sugarcane producers have reported infestations frequently ( Cruz et al., 2019). Further studies can indicate if the cecidomyiid can be used in biological control of S. sacchari in sugarcane plantation.