Plecia nessiae Fitzgerald, 2021

Fitzgerald, Scott J., 2021, New species of Neotropical Plecia Wiedemann (Diptera: Bibionidae) and delineation of the americana-, nigra-, and xyele- species-groups, Zootaxa 5005 (1), pp. 21-40 : 31-33

Plecia nessiae Fitzgerald sp. n.

( Figs. 18–22 )

Type Material. Holotype: Male, point-pinned ( NHMLA), BRAZIL: “Veadeiros, Go., Brazil, May 1, 1956, F.S. Truxal ” [white label]. “Machris Brazilian Expedition—1956, Los Angeles County Museum” [white label]. LACM ENT 395057 [white data matrix label] . HOLOTYPE, Plecia nessiae Fitzgerald [red label], terminalia dissected.

Description. Holotype Male. General coloration. Entirely black to very dark brown, legs dark brown. Head. Three ocelli. Antenna missing. Compound eye holoptic with minute sparse ommatrichia, divided into upper and lower section of larger and smaller facets by slight depression. Face produced anteriorly, duck-bill-like. Clypeus + proboscis long, longer than the length of the head (can be seen folded under the head in Fig. 18 ). Thorax. Mesonotum polished, shining, with a subtle median and a pair of more distinctive dorsocentral grooves. Anterior portion of grooves with thin dark brownish pruinosity forming longitudinal stripes, mesonotum more thickly pruinose laterally and anteriorly. Mesonotum largely bare with short dark sparse setae in median and dorsocentral grooves as well as laterally. Thoracic pleurae matte, very dark brown, katepisternum with patch of dorsal setae. Legs. Missing fore legs and left hind leg. Remaining legs with dense short dark setae. Hind tibia slender, spindle-shaped. Hind basitarsus slender, sausage-shaped, approximately 4.5 times as long as wide. Wings. 6.5 mm, slightly light brown fumose, darker anteriorly. All veins brown, anterior veins bolder, pterostigma concolorous with wing membrane. R 2+3 short, curved, strongly divergent from R 4+5, ending in C. Venation typical for the genus. Abdomen. With short dark hair. Terminalia ( Figs. 19–22 ). Epandrium (tergite nine) short, almost twice as broad as long with narrow, slit-like posteromedial cleft extending about 1/3 length of sclerite though sclerite creased along entire length. Epandrial lobes apically rather truncate, but with four broad, dark, triangular, posteroventrally-directed, shark-tooth-like lobes on the inner posterior edge. Gonocoxites distinctly convex, bulbous, ventrally broader than long, lacking posteromedian cleft, median projection, and lateral lobes. Gonostylus with two main lobes; a broad, flat dorsal lobe and a more ventral, slender posteriorly-projecting lobe. In posterior view ( Fig. 21 ), gonostylus broad, roughly diamond-shaped with broad truncate dorsal edge and dorsomedial edge black and covered in minute rasp-like teeth and ventral lobe foreshortened and difficult to see. In ventral view ( Fig. 20 ), ventral lobe of gonostylus slender, apically hooked, resembling neck and head of the Lochness Monster (as in the famous, albeit hoaxed, “surgeon’s photograph” of 1934).

Female. Unknown.

Diagnosis & Remarks. This species is most similar to P. xyele Fitzgerald , which previously had no clear affinity to other species ( Fitzgerald 1998); both species share the dark shining scutum, elongated mouthparts, and bilobate gonostylus with rasp-like dorsal lobe. However, P. nessiae can be distinguished by the shape of the epandrium (with four triangular teeth in P. nessiae verses two strong apically rounded lobes in P. xyele ) and the very different shape of the gonostylus; in ventral view, the ventral lobe of P. nessiae is slender with the apex hooked resembling the neck and head of the Lochness Monster ( Figs. 19 & 23 ) whereas that of P. xyele is rectangular, apically truncate, but with corners produced into acute points (see Fitzgerald 1998, Figs. 89–91). P. nessiae belongs to the xylele -species-group (see Discussion) and will key to couplet 5 in Hardy’s 1945 key.

Etymology. The specific epithet is derived from the name Nessie (a nickname for Scotland’s Lochness Monster) as the gonostylus in ventral view bears a striking resemblance to the neck and head of the Lochness Monster (as e.g., seen in the “Surgeon’s photograph” of 1934 (see Fig. 23 and Tikkanen 2020). Additionally, the epandrium has a row of monstrous teeth along the posterior edge.

Distribution. Known only from the holotype collected in Goiás, Brazil.

Figures

FIGURE 18. P. nessiae sp. n., holotype male, habitus. Scale bar = ca. 1.0 mm. Abbreviations: cl, clypeus.

FIGURES 19–23. P. nessiae sp. n., holotype male, terminalia. 19. Dorsal. 20. Ventral. 21. Posterior. 22. Lateral. 23. The classic 1934 “Surgeon’s photograph” of the Lochness Monster (photograph public domain); see etymology. Scale bar = ca. 0.5 mm. Abbreviations: c, cerci; gc, gonocoxite; gs, gonostylus; p, dorsal sclerite of paramere; t9, tergite nine.