Xanthonia villosula (F. E. Melsheimer)

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 : 10-11

5. Xanthonia villosula (F. E. Melsheimer)

( Figs 9 , 16, 19, 36–39; Map 6 )

Eumolpus Villosus F. V. Melsheimer 1806: 47 [nomen nudum].

Eumolpus villosulus F. E. Melsheimer 1847: 169 .

Myochrous villosulus: F. E. Melsheimer 1853: 125 .

Xanthonia villosula: Crotch 1873: 96 . Gemminger & Harold 1874: 3376. Clavareau 1914: 75.

Leng, 1920: 292. Staines & Weisman 2001a: 178. Riley et al. 2003: 153.

Eumolpus plagiatus F. E. Melsheimer 1847: 169 [as Eumolpus villosulus , var.? a].

Myochrous plagiatus: F. E. Melsheimer 1835:125 [as valid species]. Staines & Weisman, 2001a:178 [as nomen nudum].

Syntype. Not examined, sex undetermined but probably ♀, conserved in MCZ [MCZ type no. 29396] (images at MCZ type database last viewed February, 2019). This species was originally based on an unknown number of specimens from Pennsylvania. Weisman (1960) based his interpretation of this species on Melsheimer’s original description. Staines and Weisman (2001a) designated a neotype (examined, ♂, Fig 16, conserved in USNM), stat- ing that they could not locate syntype material; however, this neotype designation is invalid since a syntype exists (ICZN Art. 75.8). The syntype at the MCZ had been dissected prior to this study and the abdomen is glued to the specimen’s point. There is no microvial associated with the specimen (P. Perkins, personal communication to EGR, 2017). The margins of ventrites III–IV are finely serrate.

The name Eumolpus plagiatus of F. E. Melsheimer (1847) was mentioned as a variety of E. villosulus and accompanied by a diagnosis in that work. This name was treated as a nomen nudum by Staines & Weisman (2001a) and types were not located. This name is available from its original publication date and is here perpetuated as a junior synonym of X. villosula . It applies to either the maculate form of X. villosula or possibly to a different maculate species occurring in the geographical area where Melsheimer acquired his specimens.

Diagnosis. Moderate in size, length 2.8–3.5 mm; ground color of dorsum light reddish brown, usually immaculate or rarely with faint indications of elytral maculae ( Figs 9 , 16), venter brown; punctures 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 ventrites III–V finely evenly denticulate ( Fig 19 ); median lobe of male genitalia gently tapered distally, apex abruptly truncate with weak emargination ( Figs 36–38 ).

Range. Southern Ontario and Quebec south to South Carolina, Tennessee and Mississippi, west to Wisconsin, Nebraska, Kansas, Oklahoma and Texas ( Staines & Weisman 2001a). The records of Dawson, Yukon, and “ Colorado ” cited in Staines & Weisman (2001a) seem out of the expected range for this species and are likely incorrect. The specimens supporting these records should be reexamined. The specimens cited from Travis County, Texas in that work were not examined during the present study. In Texas, this species is known from the eastern one-third of the state ( Map 6 ).

Plant associations. This common and wide-ranging eastern species has been associated with numerous woody plants, with some of those records probably being based on other Xanthonia species (Clark, et al. 2004). The oak associations likely represent true food plants. Some Texas specimens were beaten from Quercus nigra L. and Q. sellata Wangenh ..

Seasonal distribution. Texas specimens were taken from April through June.

Remarks. A fair number of the specimens examined from Fannin County have faint to distinct dark maculation on their elytra, but otherwise the elytral color of the examined Texas material is pale. The finely and uniformly denticulate ridge on the margins of ventrites III–V and the shape of the median lobe are the important diagnostic characters separating this species from all other species of similar size and coloration.

Specimens examined. See Appendix 4. The genitalia of 15 males from 10 Texas localities were examined and from many additional specimens not from Texas.

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.

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 (●).

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.