Xanthonia parva Riley & Quinn, 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 : 12

6. Xanthonia parva Riley & Quinn , n. sp.

( Figs 5 , 18, 26 , 34–35 , 56 ; Map 6 )

Holotype. Here designated, ♂ ( Fig 56 ) with the following labels: || TEXAS: Kerr Co. | Kerr Wildlife Management Area | Spring Trap , IV-24-2005 | Coll. E. G. Riley || beating | Quercus | glaucoides Mart. & Gal. || [red label] HO- LOTYPE | Xanthonia | parva | Riley & Quinn ||. This specimen is dissected with the genitalia and abdomen mounted on the point, missing one hind leg and portion of one antenna. Deposited in TAMU.

Paratypes. (18 total) TEXAS: Kerr Co., same data as holotype [10 total, EGRC, TAMU, USNM]; same locality as holotype, IV-25-1992, E. G. Riley [5 EGRC]; Kerrville, VI-5-1956, H. & A. Howden [1 USNM]; Burnet Co. , 11.8 km. W Bertram, V-22-1989, R. S. Anderson [2 TAMU] .

Diagnosis. Size small, length 2.1–2.7 mm; dorsal ground color light to medium reddish brown, immaculate or nearly so ( Figs 5 , 56 ), venter of body light to medium brown; hairs on intervals reclined and in single rows, hairs arising from punctures appressed nearly as long as those on intervals; ventral tooth of profemur obsolete to absent; margins of ventrites III-V serrate ( Fig 18 ); median lobe of male genitalia gradually tapered distally, apex rounded with shallow v-shaped incision and short broad lobe on each side ( Fig 34 ).

Description. Color: Head light reddish brown, labrum and antennae slightly lighter shade of reddish brown. Pronotum and elytra light to medium reddish brown, elytra without dark pattern or at most with vague traces of a pattern ( Fig 5 , 56 ). Venter light to medium brownish. Legs light reddish brown. Form: Length 2.1–2.7 mm Head densely and coarsely punctate throughout and with short golden closely-appressed pubescence, face with median line faintly impressed on vertex, inter-antennal area nearly flat. Pronotum densely and coarsely punctate with short fine golden recumbent pubescence, width averaging 1.27 times length, widest at middle; lateral margins evenly broadly rounded in dorsal view; anterior transverse depression and lateral impressions obscure. Elytra length averaging 1.38 times their combined width, 2.35 times length of pronotum; basal callosity poorly developed; punctures confused over most of disc and base, tending to form rows at suture and along lateral margins and apex; punctures as large or slightly larger than spaces between punctures; intervals at lateral margins and apex slightly elevated; pubescence composed of reclining hair arranged in single lines on intervals and recurved appressed hairs arising from punctures nearly as long as erect hairs. Metasternum smooth medially, finely densely punctate laterally. Abdomen with ridge of lateral margins of ventrites III–V serrate, often irregularly serrate ( Fig 18 ); last ventrite of male flat without tubercles. Ventral tooth obsolete to absent on all femora. Median lobe of male genitalia in en-face view slightly tapered distally, apex broad, with shallow broad v-shaped incision that defines short round lobe on each side ( Figs 34–35 ).

Range. Thus far known from a limited area of the Edwards Plateau ( Map 6 ).

Plant associations. The holotype series was beaten from Lacey oak, Quercus laceyi Small (long-known in Texas as Quercus glaucoides Mart. & Gal. ).

Seasonal distribution. Taken during April and May.

Remarks. This is the smallest member of the genus occurring in Texas and not likely to be confused with other species with denticulate ventrite margins. It is most similar to X. serrata Staines & Weisman , another small species found in the eastern states but that species has a slightly differently shaped median lobe and distinct elytral pattern. Our Kerr County specimens are immaculate, but one specimen from Burnet County has a very faint indication of an elytral pattern.

Specimens examined. See types cited above. The male genitalia of seven males from two 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 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 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 (●).