Loxozus cornutus ( Walker, 1853 )

Sepúlveda, Tatiana A., de Carvalho, Claudio J. B. & Pereira-Colavite, Alessandre, 2019, Systematics of the Neotropical genus LOXOzus (Diptera: Neriidae), with notes on distribution and sexual dimorphism, Zoologia (e 26928) 36, pp. 1-6 : 2-5

Loxozus cornutus ( Walker, 1853)

Tetanocera cornuta Walker, 1853: 401 .

Loxozus cornutus ; Steyskal, 1965: 446.

Loxozus clavicornis Enderlein, 1922: 156 ; Synonymy by Steyskal, 1965: 446.

Type Material. Holotype, Tetanocera cornuta , female; Type locality: Colombia. LABELS: (1) South America, Colombia (2) Type (3) Tetanocera cornuta Walker [ NHMUK] ( Fig. 2).

Holotype, Loxozus clavicornis female; Type locality: Colombia. LABELS: Cordillieren von Columbien, terra templada, Gesammelt von Professor Dr. Thieme [ ZMHB] ( Fig. 1).

Female ( Fig. 3). Body length 5.6–8.2 mm. Wing length 7.0– 8.2 mm and width 1.9–2.2 mm; yellowish-brown with head and thorax partially yellow. One female from Venezuela is slightly paler and the Amazon specimen is the darkest.

Head. Antenna elongate, about same length as head ( Fig.4). Scape slightly constricted on basal half, length twice maximum width ( Fig. 5). Pedicel narrowed, length more than three times maximum width and slightly less than twice length of scape; inner process of pedicel wide triangular ( Fig. 6). First flagellomere brown with whitish micropubescence; dorsal and ventral margins parallel and apex widely rounded. Arista white, inserted dorso-apically on first flagellomere. Antennal bases conspicuously protrudent and separated medially by upper face. Frontogenal suture joins distal margin of antennal base. Fronto-orbital plate brown with white pruinescence; three short equidistant fronto-orbital setae, two anterior hair-like. Inner vertical seta almost hair-like. Ocellar triangle shiny and small. Parafacial brown and narrow ( Fig. 5). Gena sub-shiny yellow and wide; genal seta spine-like. Postgena densely white pruinose with several black and white setulae. Occiput shiny brown, with wide yellow median stripe.

Thorax. Yellowish-brown pruinose with two dorsal white stripes, separated by a wide median brown stripe; pleura pruinose. Presutural scutum longer than postsutural scutum. One dorsocentral seta. Scutellum yellowish-brown pruinose with wide median yellow stripe; apical setae thick, slightly shorter than dorsal length of scutellum. Postpronotal lobe bare and yellow dorsally. Anterior notopleural seta absent, posterior notopleural seta spine-like, inserted on tubercle. Katepisternum with one short dorsal seta. Vein dm-cu very oblique ( Fig. 7). Basicosta with one seta. Halter yellow, with black and orbicular knob. Coxae yellowish-brown; fore coxa with two antero-apical setae and two anterolateral setae; mid coxa with three lateral setae; hind coxa with one lateral seta. Femora brownish-yellow; fore femur with several anteroventral and posteroventral spine-like setae on distal third; mid femur with two median setae on anterior margin and anteroventral and posteroventral spine-like setae on distal third; hind femur with two dorsal distomedian setae and anteroventral and posteroventral setae on distal third. Tibiae brownish-yellow with dark apex ( Fig. 3) and slightly wider distally ( Fig. 8). Basitarsomere short, less than 1/4 length of tibia.

Abdomen. Dark yellowish-brown with black setulae and lateral margins slightly paler. Oviscape dark yellowish-brown, darker medially and at apex.

Male ( Fig. 9). Body length 9.1–10.4 mm; larger males with darker tegument. Wing length 6.7–8.0 mm and width 1.8–2.3 mm. Three fronto-orbital spine-like setae. Inner vertical seta spine-like. Parafacial with yellow medial stripe. Gena brown and shiny; genal seta not inserted in tubercle. Femora brown; fore femur with anteroventral spine-like setae inserted on digitiform tubercles and posteroventral spine-like setae short. Fore tibia brown; distal third conspicuously swollen with thick apical spine-like setae ( Fig. 10); two lines of outstanding spine-like setae posteriorly ( Fig. 11). Each tarsomere with dense and thick setae posteriorly and near apex; fifth tarsomere ovate, narrow proximally.

Terminalia. Epandrium yellowish-brown and cylindrical; slightly longer than syntergosternite 8; cercus wide linear with wide round apex and yellow thin setae; surstylus wide linear with wide rounded apex and sparse yellow thin setae at apex and almost as long as cercus, but narrower; distiphallus linear and partially sclerotized, distally bifurcated in one membranous short spike and one long membranous flexible tube ( Fig. 12).

9 Tergite 6 10 Flexible tube Spike Distiphallus 12 Surstylus Ejaculatory apodeme Hypandrium Cercus Phallapodeme Pregonite 11

Material examined. Venezuela. 1 female, 30.i.1967 - E. Miranda, Qda. Quintero- Caracas, col. J. M. A. Ayala L. [ USNM, 2014]. BRAZIL. 1 female, RO. Monte Negro, Fazenda Amorin , 248m, S 10°40’6” W 63°29’0”, Sweeping, 03-15.xii.2011, Amorin, Ament & Riccardi col. SISBIOTA, CNPq-FAPESP [ MZUSP, 2013] . PERU. 1 male, Previsto , 800 m, 17.vi.1965, J. Shunke. B. M. 1965-529 [ NHMUK, 2012]; 1 female, (1) Madre de Dios: Manu, Erika (near Salvación), 550, 5-6, sept.1988, A. Freidberg (2) Loxozus clavicornis Det. M. Buck, 2002 [ USNM, 2018] . BOLIVIA. 2 females, (1) Rurrenabaque, Beni Bolivia, WMMann (2) oct (3) Mulford, BioExpl, 1921-22 [ USNM, 2015, 2016]; 1 male and 1 female, (1) Rurrenabaque, BeniBolivia, WMMann (2) oct (3) Mulford, BioExpl, 1921-22 (4) Loxozus clavicornis End. Det. G. Steyskal, 1953 [ USNM, 2017, 2026] .

Distribution. Colombia, Venezuela *, Brazil *, Peru *, Bolivia ( Fig. 13).

Remarks. After examining the holotypes of T. cornuta and L. clavicornis , we confirm the synonymy of these species and reiterate that the correct name of the species is Loxozus cornutus .

The only phylogenetic study of Neriidae ( Koch et al. 2015) , recognized two main Neotropical lineages in the family: the Eoneria -group and the Nerius -group. Although L. cornutus was not included in that study, according to the synapomorphies proposed for each of those two lineages, we hypothesize that L. cornutus is closely related to other species of the Nerius -group (i.e. strong increase in female size; presutural scutum longer than postsutural scutum; several changes in wing venation; polished and shiny antennal base; reduction in setae length; lack of occipital setae; and reduction in the number of setae on both basicosta and male fore coxae). Within Nerius -group, Loxozus , seems to be morphologically related to Nerius Fabricius, 1805 by the peculiarly wide inner process of pedicel and prosternum. Loxozus cornutus can be easily recognizable from any other neriid for its narrow and long antennae, separated by at least twice the length of the scape at base.

Half of the genera of Neriidae present sexual dimorphism, including Antillonerius Hennig, 1937 (Sepúlveda and Souza unpublished data), Indonesicesa Koçak & Kemal, 2009 ( Aczél 1954), Longina Wiedemann, 1830 ( Buck and Marshall 2004), Telostylus Bigot 1859 ( Steyskal 1966) and the species Glyphidops bullatus ( Enderlein, 1922) ( Sepúlveda et al. 2014) and Telostylinus angusticollis ( Enderlein, 1922) ( Bonduriansky 2009) . In these genera, the males have elongated head and antenna and/or elongate legs with or without conspicuous spines. Males of L. cornutus can reach almost twice the size of a small female and the colors are darker in larger representatives. The male fore tibia is swollen ( Fig. 10) with thick spine-like setae posteriorly ( Fig. 11), conspicuously differentiated from the female thin tibia ( Fig. 8). This swollen appearance of the fore leg in males is also present in other genera of Neriidae , including Indonesicesa , Longina and Telostylus . These traits play an important role in male-male competition for oviposition sites, whereas larger and stronger males will have more access to females. This sexual selection drives the evolution of the shape of the body of males ( Bonduriansky 2006).

The genital morphology of L. cornutus is not very differentiated from other Neotropical Neriidae , which also present the pattern described for D. angusticollis by Bath et al. (2012): “Where the middle section (basal part of distiphallus) joins the distal section (distal part of distiphallus), both species possess a rigid spike”... “and the distal section is a long, unsclerotized, flexible tube, which is coiled up at the base of the epandrium when the genitalia are retracted”.