Hydrellia egeriae, Júnior, Francisco De Assis Rodrigues, Mathis, Wayne Nielsen & Hauser, Martin, 2015

Júnior, Francisco De Assis Rodrigues, Mathis, Wayne Nielsen & Hauser, Martin, 2015, Argentine Hydrellia Robineau-Desvoidy (Diptera, Ephydridae): new species and key to identification, Zootaxa 3957 (1), pp. 131-136 : 133-136

Hydrellia egeriae sp. nov.

(Figs.: 1–3.3)

Cabrera Walsh et al. 2013: 133–147 (as Hydrellia sp. 1 and 2) [ecology; host plant: Egeria densa Planchon (Hydrocharitaceae) ].

Diagnosis. Body length of male: 1.86–2.07 mm ( Fig. 1 ); Female: 1.70–2.09 mm; ocellar setae three times shorter than pseudopostocellar; face usually wholly golden microtomentose; dorsocentral setae 1+1; tarsi dark brown ( Fig.1 ); ctenidial setae along anteroventral margin of forefemur minute; sternite 4 and 5 of male apparently divided (Figs. 2.1 and 2.2); lateral arms of sternite 5 covered with many long hair-like setulae on posterior margin and many spine-like setae concentrated on inner mid- posterior margin (Figs. 2.1 and 2.2); aedeagus, in lateral view, with a pointed, shallowly recurved process on dorsal margin (Fig. 2.4); surstylus larger than wide, posterior margin concave, narrow medially, with a small mid apical cleft, forming broad lateral arms, each lateral arm with a small concavity lateroapically (Fig. 2.7); sternite 8 setulose, convex on anterior margin, pointed on posterior margin, projecting under the cerci (Fig. 3.1).

Description. Head ( Fig. 1 ): frons broader than high; frontal vitta golden brown; fronto-orbital plate opaque brown to black; ocellar setae present, three times shorter than pseudopostocellar setae; both proclinate and lateroreclinate fronto-orbital setae present, with a third shorter setulae between both; antenna mostly dark brown to black, first flagellomere with grayish micropubescence ventrobasally; pedicel without prominent setae on dorsal margin, but with 2 ventral hair like setulae; face usually wholly golden microtomentose, sometimes silver, and in few cases golden microtomentose only medially and silvery along the row of facial setae; bearing 4–6 facial setae (usually 5); parafacial usually concolorous with face; face in lateral view nearly vertical, but with a small medial carina and shallow but distinct antennal grooves; lunule silver; gena, postgena and occiput silvery gray, genal groove dark brown to black; maxillary palpus yellow, spatulate, bearing two setulae; epistomal ratio: 1.56–1.58; mesofacial ratio: 2.03–2.06; vertex ratio: 5.20–5.30; eye-to-gena ratio: 2.84–3.72; head ratio: 1.29–1.33.

Thorax ( Fig. 1 ): well-developed dorsocentral setae 1+1; mesonotum densely dark brown microtomentose; pleurae silvery gray, except for brown microtomentose notopleura; 1 mesokatepisternal seta; 3 scutellar setae, mid pair weakly developed; 1 postpronotal seta. Wings ( Fig. 1 ): length 1.85–2.32 mm; hyaline with brown venation; knob of halter fluorescent yellow to whitish yellow, stem pale brown; costal sections indices: II/I: 1.74–1.84; III/ IV: 2.80–2.92; V/IV: 3.06–3.19; vein M ratio: 3.39–3.79. Legs ( Fig. 1 ): mostly silvery gray microtomentose, joints brown; posterior margin of mid and hind femur glossy brown; tibiae mostly brown; tarsi dark brown; ctenidial setae along anteroventral margin of forefemur minute.

Abdomen ( Fig.1 ): brown microtomentose dorsally, concolorous with mesonotum; in lateral view silvery gray. Male terminalia: sternite 4 apparently divided or unsclerotized medially, as sternite 5, setulose and with spine-like setae on inner medial margin (Figs. 2.1 and 2.2); sternite 5 attached with anterior margin of hypandrium, apparently divided, anterior margin truncate, pointed anterolaterally, lateral arms covered with many long hair-like setulae on posterior margin and many spine-like setae concentrated on inner mid- posterior margin (Figs. 2.1 and 2.2); postsurstylus with an inner rounded membrane (Fig. 2.2); pregonite rod-like, except for the apical bifurcation, each lobe bearing an apical setulae (Fig. 2.2); epandrium broad, forming an inverted U (Fig. 2.1); phallapodeme in ventral view Y shaped, bifurcated on posterior margin (Fig. 2.5), in lateral view shallowly sinuous medially (Fig. 2.6); aedeagus in ventral view fusiform (Fig. 2.3), in lateral view with a pointed, shallowly recurved process on dorsal margin (Fig. 2.4); surstylus larger than wide, posterior margin concave, narrow medially, with a small mid apical cleft, forming broad lateral arms, each lateral arm with a small concavity lateroapically (Figs. 2.1 and 2.7); Female terminalia: sternite 6 rounded trapezoidal (Fig. 3.1); sternite 7 rounded quadrate (Fig. 3.1); sternite 8 setulose, convex on anterior margin, pointed on posterior margin, projecting under the cerci (Fig. 3.1); tergites subequal in length (Fig. 3.2); cerci ovoid (Fig. 3.2); hypoproct small, flap-like (Fig. 3.2); ventral receptacle with a cap cupuliform, as broad as large, with an extended process, J-shaped in lateral view (Fig. 3.3).

Material examined. Holotype male ( USNM): Argentina: 8 km SE Campana, Buenos Aires province (34 14’ 0 4 S, 58 52’ 32 W); USDA-ARS laboratory colony Albany, CA VII-25-2013; J. Herr coll. Paratypes: labeled the same as holotype (7 males / 7 females in MNRJ and 8 males / 7 females in USNM); 10 males, 10 females CSCA, 1 male ( CSCA FTC: #13M460) GenBank accession number (CO1): KJ703244 ); Hurlingham, Buenos Aires province (3435’14 S, 5838’27 W); USDA-ARS laboratory colony Albany, CA. VII-25-2013; J. Herr coll. (8 males / 7 females in MNRJ and 7 males / 8 females in USNM); 1 female ( CSCA FTC: #13M459), GenBank accession number (CO1): KJ703243 ).

Distribution. Neotropical: Argentina (Campana and Hurlingham).

Etymology. The specific epithet egeriae refers to the host plant Egeria densa Planchon , with which this species is associated and feeds during the larval stage.

Notes. Hydrellia egeriae is very similar to H. schneiderae Rodrigues-Júnior, Mathis & Couri and H. vulgaris Cresson , but can be distinguished by the shape of sternite 5, aedeagus and the discrepancy of surstylus of male and sternite 8 of female.

DNA results. When comparing the two identical CO1 sequences of Hydrellia egeriae with sequences in the BOLD database, we could not find any close matches. The most similar results were Scatophagidae with 89.37% similarity. The first ephydrid ( Hydrellia griseola ) had a 88.96% similarity with our sequences. The results for a BLAST-search in GenBank were similar, with the closest matches being Muscidae and Calliphoridae with 89% similarity. In general intraspecific variation is less than 2% and between genera 7%. Of course there are significant differences in certain taxonomic groups. The reason for this poor match is very likely the lack of Hydrellia sequences in these databases – only a few species were available in these databases. Furthermore, comparing our CO1 sequence with the two available Hydrellia sequences on GenBank, H. tritici (EU493564.1) and H. pakistanae (EU493563.1), yielded a similarity of 83% and 86% respectively. The comparison between H. tritici (EU493564.1) and H. pakistanae (EU493563.1) yielded 87% similarity. This could be an indication that the genus Hydrellia includes very divergent species. The new species is from the Neotropics, while H. pakistanae is from the Oriental region and H. tritici from Australia. The aim of this paper is to characterize and name a new potential biocontrol agent and not to revise the genus Hydrellia . Therefore the sequences of H. egeriae are to aid identifications, especially of immature stages or females. The comparison with other Hydrellia DNA indicates that there is need for further investigations into the phylogenetic relationships of Hydrellia and that much more sequencing is needed before any taxonomic conclusions can be drawn.

Figures

FIGURE 1. H. egeriae sp. nov. (holotype), profile.