Oncometopia nigricans (Walker, 1851)

(Figs. 1 I–P, 3)

Proconia nigricans Walker 1851: 783 [n. sp.]

Proconia nigricans; Young 1965b: 185 [lectotype designated]

Oncometopia (Oncometopia) nigricans; Metcalf 1965: 571 [catalogued]

Oncometopia (Oncometopia) nigricans; Young 1968: 227 [fig. 211] Oncometopia (Oncometopia) nigricans; McKamey 2007: 309 [catalogued] Proconia marginata Walker 1851: 785 [n. sp.]

Proconia marginata; Young 1965b: 183 [holotype clarified]

To Oncometopia (Oncometopia) nigricans; Metcalf 1965: 571 [catalogued]

To Oncometopia (Oncometopia) nigricans; Young 1968: 227 [n. syn.] Oncometopia (Oncometopia) nigricans McKamey 2007: 309 [catalogued] Proconia tenebrosa Walker 1851: 787 [n. sp.]

Proconia tenebrosa; Young 1965b: 195 [holotype clarified]

To Oncometopia (Oncometopia) nigricans; Metcalf 1965: 571 [catalogued] To Oncometopia (Oncometopia) nigricans; Young 1968: 227 [n. syn.] Oncometopia (Oncometopia) nigricans McKamey 2007: 309 [catalogued]

Description. Length: male 10.0– 12.2 mm, female 11.1–12.8 mm. External structure as in O. orbona .

Coloration. As in O. orbona, except the forewing veins usually being contrastingly dark and narrowly outlined with dark; dark pattern on the rest of the body more extensively developed (Figs. 1 I–P, 3A).

Male terminalia. Aedeagus not compressed laterally, in lateral view (Fig. 3C–I) approximately as long as tall; base long, its dorsal surface in lateral view only slightly shorter than height of shaft, with broad concavity on transition to shaft, ventral surface of base extended into slender ascending process, approximately as long as shaft; shaft in caudal view (Fig. 3B) expanded in basal half, narrowly parallel-sided in apical half, on ventral surface near middle with membranous stalk bearing spiniform process (in one examined specimen, two processes). Other characters as in O. orbona .

Female terminalia. Sternum VII as in O. orbona (Fig. 3J). Vestibulum (Fig. 3K) with posterior margin produced into a tapering extension, approximately as long as its basal width. Sternum VIII membranous. Genital chamber sclerites (Fig. 3K, shaded) deltoid, unsculptured, attached to dorsal surface of 1st valvulae at level of articulation with 1st valvifers, forming ventrolateral walls of vestibulum extension, their dorsolateral margins undulate, posteromedially fused into loop. Bases of 1st valvulae (Fig. 3L) produced well anterad of articulation with 1st valvifers, with spinose microsculpture, except on commissural surface.

Distribution. Florida, north into southern Georgia (Fig. 4 R). One examined female (USNM) has been collected in New Orleans, Louisiana. Additionally, one male (INHS) has the label “L.O. Mountain, Tennessee,” possibly referring to the Lookout Mountain near the border with Georgia. Sympatric with O. orbona in southern Georgia and northern Florida.

Types. The lectotype, male, collected at St. John’s bluff in Duval County, northeastern Florida, and preserved at BMNH, has been designated by Young (1965b) and was not examined in this study. The type of the junior synonym, O. marginata (Walker), from the same locality, was examined (BMNH).

Material examined. 110 specimens from Florida, 14 from Georgia, one from Louisiana, and one from Tennessee .

Notes. The species is similar to O. orbona in coloration and body proportions (Figs. 1 I–P, 5). Most Florida specimens (Fig. 1 I–N) can be distinguished from O. orbona by the somewhat more produced crown, more extensive development of dark pattern on all body parts, and particularly by dark stripes surrounding veins on the forewing. The latter condition is unique among Oncometopia . However, some of the examined specimens from northern Florida and all those from southeastern Georgia (Fig. 1 O, P) are externally identical to O. orbona . Despite the overlap in the external characteristics, the two species are well differentiated in both the male and female genitalia. The only exception among the studied material was a female from Jacksonville, Florida, in USNM collection, which has the genitalia intermediate between orbona and nigricans (Fig. 3 M, N). In the same series (label: “Jacksnville [sic!], Fla”), two males displayed the morphology typical of O. nigricans, and one male and one female the morphology typical of O. orbona . The female with intermediate characters displayed a combination of bases of the 1st valvulae in dorsal view inflated along anterior margin (Fig. 3 M) and sternum VIII sclerites (Fig. 3 M, shaded), both characteristic of O. orbona, with the presence of deltoid genital chamber sclerites (Fig. 3 M, also shaded), although not extending posteriorly as far as in typical O. nigricans (Fig. 3K). The specimen lacks dark stripes on the forewing veins; among the two examined males of O. nigricans from this locality one also lacked the stripes. Young (1968) pointed out that an intermediate form between O. orbona and O. nigricans occurs in northern Florida and in southern Georgia and tentatively suggested that it was an undescribed species. Among illustrations he included for that form, the vestibulum of a female from Homerville, Georgia (Young 1968: fig. 209n) matches well the Jacksonville specimen, described above, while the aedeagus of a specimen “from Georgia ” (ibid., fig. 209f) clearly belongs to O. orbona, and those of specimens from Homerville and Jacksonville (ibid., fig. 209 j, k, m) belong to O. nigricans . Thus, no males of the intermediate form are known. Because the rare female variant occurs in the contact zone between the ranges of O. orbona and O. nigricans (Fig. 4 R) it appears to be a hybrid between the two species.