Xanthonia nitida Weisman, 2019

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 : 15-16

9. Xanthonia nitida Weisman , n. sp.

( Figs 4 , 50–52 , 60 ; Map 2 )

Holotype. Here designated, ♂ ( Fig 60 ) with labels and attachment as follows: || Dallas TX | 25.IV.07 || Schwarz & | Pratt Coll || 69 || NM || [glycerine-filled microvial containing male genitalia] || [red label] HOLOTYPE | Xanthonia | nitida | Weisman ||. This specimen is dissected with the abdomen glued on the point and the median lobe contained in a glycerine-filled microvial, missing terminal segment of one antenna, otherwise appendages intact. Deposited in USNM.

Paratypes (5 total): TEXAS: Bexar Co. San Antonio, IV-8-1945, duBois [1 USNM]; Blanco Co. Cypress Mills, IV-2, Chittenden Collection [1 USNM]. Dallas Co. Same data as holotype [2 USNM]; same locality, IV-20-1907, Schwarz & Pratt [1 USNM] .

Diagnosis. Size small to moderate, length 2.8–3.0 mm; dorsal ground color dark brown to nearly black, without obvious pattern of maculae ( Figs 4 , 60 ), venter dark brown to black; elytral hairs composed of erect hairs in single rows on intervals and appressed hairs arising from punctures nearly as long as erect hairs; ventral tooth of profemur minute to obsolete; lateral margins of all ventrites entire; median lobe of male genitalia gradually tapered distally, apex rounded with short V-shaped incision separating a short rounded lobe on each side ( Fig 50–51 ).

Description. Color: Head dark reddish brown, labrum and antennae yellowish brown. Pronotum and elytra uniformly dark reddish brown to black, pattern not evident ( Fig 4 , 60 ). Venter varying from entirely dark reddish brown to black or forms with meso- and metathorax and abdomen dark. Legs dark reddish brown. Form: Length 2.8–3.0 mm Head densely and coarsely punctate throughout, punctures very shallow on clypeal area, with short closely appressed pubescence; face with median line moderately impressed and extending to vertex; interantennal area slightly concave. Pronotum densely and very coarsely punctate with short yellow recumbent pubescence, length averaging 1.35 times width, widest behind middle; lateral margins very broadly rounded in dorsal aspect; anterior transverse depression and lateral impressions absent. Elytra length averaging 1.35 times combined width, 2.35 times length of pronotum; basal callosity obscure; punctures in irregular rows which tend to be double, confused near scutellum, behind sulcus and below humeri; punctures as large as intervals on disc; intervals nearly flat on disc, becoming weakly costate on lateral areas and at apex; pubescence composed of erect bristle-like hairs in single lines on every other interval and appressed hairs arising from punctures nearly as long as erect hairs. Metasternum with lateral areas coarsely punctate and rugose. Ventral tooth on all femora minute to obsolete. Abdomen with ridge on lateral margins of all ventrites entire, last ventrite of male flat without tubercles. Median lobe of male genitalia in en-face view gradually tapered distally, apex rounded with short v-shaped incision defining short rounded lobe on each side ( Figs 50–52 ).

Range. Confined to Texas, primarily on the Edwards Plateau, from Val Verde County north to Dallas County and as far west as the Glass Mountains in Pecos County ( Map 2 ).

Plant Associations. None reported by Weisman (1960), but during the present study it was found abundant on Quercus buckleyi Nixon & Dorr , Q. mohriana Buckley and Q. vaseyana Buckley. Specimen numbers during the Travis County study were low, but most were taken on Q. buckleyi and Q. fusiformis Small (Table 1).

Seasonal distribution. Collection dates range from late March to late May. Specimen numbers during the Travis County study were low, but all were taken from early April to late May, most during April.

Remarks. The overall dark coloration of the body with no discernable dorsal elytral pattern and the shape of the male genitalia are diagnostic.

Specimens examined. See Appendix 7. The male genitalia of 21 males from eight localities were examined.

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 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 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.

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 (●).