Xanthonia angulata Staines and Weisman, 2001

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 : 14-15

8. Xanthonia angulata Staines and Weisman

( Figs 1 , 20 , 58 , 64–68 ; Map 5 )

Xanthonia angulata Staines & Weisman 2001a: 160 . Riley et al. 2003: 152.

Xanthonia striata: Staines & Weisman 2001a: 173 (in part).

Holotype. Examined, ♂ ( Fig 58 ) with the following labels and attachment: || Glen Echo | VI 28 30 Md || JCBridwell | coll || ♂ || [glycerine-filled microvial containing male genitalia] || [red label] HOLOTYPE | XANTHONIA | AN- GULATA | Staines & Weisman ||. This specimen is dissected with the abdomen glued on the point and the male genitalia contained in a glycerine-filled microvial, all appendages intact. Conserved in USNM .

Diagnosis. Size moderate to large, length 3.5 to 4.0 mm; ground color of dorsum medium reddish brown with the pronotum notably darker than elytra, elytra immaculate ( Fig 1 , 58 ), venter dark brown to black; punctation of elytral disc in regular rows; hairs on elytral intervals long and suberect, those emerging from punctures short and appressed; ventral tooth of profemur minute; lateral margins of all ventrites entire; median lobe of male genitalia long not tapered distally, distal emargination broad and shallow, v-shaped, lobes on each side subtriangular, divergent, with left lobe side slightly smaller than right lobe ( Fig 67 ).

Range. Recorded from District of Columbia, Indiana, Kansas, Maryland, Missouri, Tennessee, and Virginia ( Staines & Weisman 2001a). Also identified from Arkansas, Oklahoma and Texas in the present study. The only confirmed Texas specimens are from Bastrop County ( Map 5 ).

Plant Associations. Staines and Weisman (2001a) record Quercus sp. Most of the Bastrop County specimens were beaten from Quercus marilandica Münchh. , and it has been recorded from oaks in other states (EGR personal observations).

Seasonal distribution. The Texas specimens were collected from April through June.

Remarks. Staines and Weisman (2001a) cite specimens of Xanthonia striata from Bastrop and Travis counties in Texas. Close examination of specimens representing the Bastrop County records show that they are misidentified examples of X. angulata . In making this determination, we follow the original work of Weisman (1960) who states that X. angulata can be separated from X. striata by the more shallow apical emargination and the divergent apices at the apex of the median lobe (compare Figs 69–72 to Figs 64–65, 67 ). The Texas material we assign to X. angulata has the tip of the median lobe less laterally angled and with a broad, more triangular lobe on each side ( Fig 67 ). A further difference between these two species is weakly indicated in Weisman’s original figures but more pronounced in the material examined during the present study (including that from Arkansas, Missouri and Oklahoma), namely the apices of the median lobe are unequal, that on the left (in en-face view) being slightly smaller than that on the right ( Fig 67 ). This slight asymmetry is not seen in any other Xanthonia species known to us. The median lobes of these species differ further in their lateral profiles. In X. angulata most of the length is nearly straight with a relatively smaller portion of overall length comprising the deflexed tip ( Fig 66, 68 ), whereas in X. striata a greater portion of overall length comprises the deflexed tip ( Fig 73 ).

Weisman (1960) identified material of X. striata mostly from states much further to the east of Texas and the Great Plains. Many of the specimens representing records published in Staines and Weisman (2001a) but not included in Weisman’s original work should be re-examined. During the course of our study, we examined the ho- lotype of X. striata ( Fig 59 ).

Specimens examined. See Appendix 6. The genitalia of six males from one Texas locality were examined and from numerous specimens from other states. In the appendix we also cite confirmed records for Arkansas, Missouri, and Oklahoma.

Figures

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 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 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.

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.

MAPS 1–6. Distribution of Xanthonia species. 1) X. vagans; 2) X. furcata (■), X. marquai (♦), X. nitida (●); 3) X. hirsuta; 4) X. picturata; 5) X. angulata (♦), X. dentata (●), X. querci (■); 6) X. parva (■), X. villosula (●).