Xanthonia, Baly, 1863

Riley, Edward G., Weisman, Donald M. & Quinn, Michael A., 2019, A taxonomic review of the Xanthonia species occurring in Texas (Coleoptera: Chrysomelidae, Eumolpinae), Zootaxa 4668 (1), pp. 1-29 : 3

Key to Xanthonia species of Texas

1 Tooth of profemur large ( Figs 21–22 ); large species, length 3.8–6.1 mm; apex of median lobe of male genitalia long and narrow, apex acute not incised ( Figs 27–31 )....................................................................... 2

- Tooth of profemur moderate in size to minute or nearly obsolete ( Figs 23–26 ); small species, length 2.1–4.0 mm; apex of median lobe of male genitalia narrow or broad, truncate or incised ( Figs 32–54 , 64–75 )................................ 3

2 Elytra appearing mottled due to clumping of variable darker and lighter hairs and usually variably alternating light and dark brown coloration of integument ( Fig 10 ).................................................. 1. X. vagans (LeConte)

- Elytra of uniform brownish coloration, hairs uniformly pale brownish and integument of uniform medium brown color ( Fig 11 )...................................................................... 2. X. marquai Riley & Quinn n. sp.

3 Tooth of profemur moderate ( Fig 23 ); venter and legs dark brownish, elytral dark brown with darker pattern ( Figs 6 , 15)................................................................................ 3. X. picturata Weisman n. sp.

- Tooth of profemur minute to obsolete ( Figs. 24–26 ); color of venter, legs and elytra, and elytral pattern variable.......... 4

4 Ridge on lateral margins of abdominal ventrites III–V minutely denticulate ( Figs 17–19 )............................. 5

- Ridge on lateral margins of abdominal ventrites III–V entire, uniformly sharp ( Fig 20 ).............................. 7

5 Median lobe of male genitalia truncate apically ( Figs 36–38 ); punctation of elytral disc subseriate, formed into more-or-less distinct rows; elytra usually without pattern of dark maculae or if present (rarely), ground color is light reddish brown [eastern Texas]......................................................................... 4. X. villosula (Melsheimer)

- Apex of median lobe of male genitalia with conspicuous median incision; punctation of elytral disc confused to subseriate; elytral pattern variable [central and western Texas]........................................................... 6

6 Elytra with distinct pattern of dark maculae ( Fig 2 , 55 ), ground color dark brown; apex of median lobe narrowed with moderately deep median incision ( Fig 40–43 ); setae arising from elytral intervals erect and long, imparting bristly appearance; larger, length 2.8–3.4 mm [mountainous regions of western Texas]........................... 5. X. dentata Staines & Weisman

- Elytra without distinct pattern of dark maculae, ground color light reddish brown; apex of median lobe with broad moderately deep median incision ( Fig 34 ); setae arising from elytral intervals reclining, moderate in length, not imparting an especially bristly appearance; smaller, length 2.1–2.7 mm [central Texas]........................ 6. X. parva Riley & Quinn n. sp.

7 Elytral setae dense, all setae appressed, of near uniform length and curvature and with seta emerging from punctures slightly shorter than those emerging from interstitial areas; tip of median lobe with deep, narrow, parallel-sided incision ( Fig 45 )................................................................................. 7. X. hirsuta Weisman n. sp.

- Elytral setae distinctly duel with setae emerging from punctures shorter, lying nearly flat against elytral surface, strongly curved, and setae emerging from interstitial areas long, reclining and weakly curved; tip of median lobe variable, but not as above............................................................................................... 8

8 Elytra uniformly medium brown, immaculate; larger, length 3.5–4.0 mm; punctation of elytral disc subseriate; median lobe long, broad throughout length, with deep angular apical incision ( Fig 67 )............... 8. X. angulata Staines & Weisman

- Elytra either uniformly dark reddish brown or medium to pale brownish usually with variably developed pattern of dark maculae ( Figs 3–4, 6–8 ); smaller, length 2.5–3.5 mm; punctation of elytral disc subseriate to confused; median lobe variable, but not as above............................................................................................ 9

9 Abdominal ventrites and most of metasternum dark, nearly black; dorsum uniformly dark reddish brown lacking dark pattern or pattern barely discernable; median lobe ( Figs 51–52 ).................................. 9. X. nitida Weisman n. sp.

- Abdominal ventrites and most of metasternum medium to pale brownish; dorsum pale to medium brown usually with variably developed pattern of darker maculae..................................................................... 10

10 Apex of median lobe of male genitalia broad with broad rounded deep incision ( Figs 47–48 ); femora pale; elytral pattern when well developed as in figures 8 and 76............................................... 10. X. texana Weisman n. sp.

- Apex of median lobe narrowed with narrow shallow incision; knee of leg or apex of femora often vaguely darker than remain- der of leg........................................................................................... 11

11 Apex of median lobe of male genitalia with lobe on each side blunt ( Figs 53 ); femora without dark spot at midlength; elytral pattern as in figures 7 and 77 [central Texas].......................................... 11. X. querci Weisman n. sp.

- Apex of median lobe of male genitalia with lobe on each side acute ( Figs 74 ); femora often with conspicuous dark spot at midlength; elytral pattern as in figures 3 and 78 [northeastern Texas]...................... 12. X. furcata Staines & Weisman

Figures

FIGURES 17–26. Xanthonia species, margins of ventrites III–V. 17) X. dentata; 18) X. parva; 19) X. villosula; 20) X. angulata. Figs. 21–22. Xanthonia species, profemora. 21) X. vagans; 22) X. marquai; 23) X. picturata; 24) X. hirsuta; 25) X. texana; 26) X. parva.

FIGURES 27–54. Xanthonia species, en-face and lateral view of median lobe. 27) X. vagans (Palmerlee, Arizona); 28–29) X. vagans (Chisos Mts., Texas); 30–31) X. marquai (Jeff Davis Co., Texas); 32–33) X. picturata (Gonzales, Texas); 34–35) X. parva (Kerr Co., Texas); 36) X. villosula (Miller, Indiana); 37) X. villosula (Dallas, Texas); 38–39) X. villosula (Natchez, Mississippi); 40) X. dentata (Socorro Co., New Mexico); 41) X. dentata (Sapello, New Mexico); 42) X. dentata (Chisos Mts., Texas); 43–44) X. dentata (Cloudcroft, New Mexico); 45–46) X. hirsuta (Dallas, Texas); 47–49) X. texana (Victoria, Texas); 50) X. nitida (San Antonio, Texas); 51–52) X. nitida (Dallas, Texas); 53–54) X. querci (Dallas, Texas). All figures from Weisman (1960), except 30–31 and 32–33.

FIGURES 64–75. Xanthonia species, en-face and lateral view of median lobe. 64) X. angulata (Washington, DC); 65–66) X. angulata (Mt. Vernon, Virginia); 67–68) (Bastrop State Park, Texas), 69); X. striata (Flatbush, New York); 70) X. striata (Nelson Co., Virginia); 71) X. striata (Wolfville, Maryland); 72–73) X. striata (Hanover, Pennsylvania); 74–75) X. furcata (Union Co., Illinois). All figures from Weisman (1960), except 67–68.

FIGURES 10–12. Xanthonia species, dorsal habitus. 10) X. vagans (Cochise Co., Arizona); 11) X. marquai (Jeff Davis Co., Texas); 12) X. hirsuta (Travis Co., Texas). Scale bars = 1 mm. Figs 13–16. Xanthonia species, types and type labels. 13) X. vagans (courtesy of the MCZ type database); 14) X. marquai; 15) X. picturata; 16) X. villosula.

FIGURES 1–9. Xanthonia species, dorsal habitus. 1) X. angulata (Bastrop Co., Texas); 2) X. dentata (Jeff Davis Co., Texas); 3) X. furcata (Wood Co., Texas); 4) X. nitida (Pecos Co., Texas); 5) X. parva (Kerr Co., Texas); 6) X. picturata (Robertson Co., Texas); 7) X. querci (Val Verde Co., Texas); 8) X. texana (Bandera Co., Texas); 9) X. villosula (Bossier Parish, Louisiana). Images to scale, scale bar = 1 mm.

FIGURES 55–60. Xanthonia species, types and type labels. 55) X. dentata; 56) X. parva; 57) X. hirsuta; 58) X. angulata; 59) X. striata, 60) X. nitida.