Ceroptres cornigera Melika & Buss, 2002

Lobato-Vila, Irene & Pujade-Villar, Juli, 2019, Revision of world Ceroptresini (Hymenoptera: Cynipidae) with the description of a new genus and five new species, Zootaxa 4685 (1), pp. 1-67 : 26

Ceroptres cornigera Melika & Buss, 2002

( Figures 3 e–g; 6a, b)

Ceroptres cornigera Melika & Buss, 2002 . Fla. Entomol. 85(4): 626. Type material: USNM (holotype), paratypes in USNM, AMNH, PHMBL and UK.

Type material (examined). HOLOTYPE (♀) with the following labels: ‘ USA, KY., Fayette Co. Lexington, Q. palustris , 21.04.998, leg. Eliason E. A.’ (white label) / ‘ex green gall em. 04.05.998’ (white label) / ‘ex gall of Callirhytis cornigera (O. S.)’ (white label) / ‘ HOLOTYPE Ceroptres cornigera Melika and Eliason , desig. G. Melika 999’ (red label) / ‘USNMENT 00892417’ (white label, QR code). PARATYPES (5♂ & 2♀) deposited in USNM with the same data as the holotype, USNMENT 00892417 (♂); USNMENT 00892426 (♀); em. 18.05.998, USNMENT 00892805 (♂); em. 18.05.998, USNMENT 00892412 (♀); 28.04.998, em. 18.05.998, USNMENT 00892811 (♂); 28.04.998, em. 18.05.998, USNMENT 00892911 (♂); 07.07.998, em. 18.05.998, USNMENT 00892729 (♂).

Diagnosis. Ceroptres cornigera is morphologically almost identical to C. frondosae Ashmead, 1896 , from which differs only by having POL about 2.0 times as long as OOL ( Fig. 3g ) (POL 3.0 times as long as OOL in C. frondosae , Fig. 3k ) and OOL 1.5 or more times as long as diameter of lateral ocelli ( Fig. 3g ) (subequal in C. frondosae , Fig. 3k ). It also has a medial ridge in the depressed area delimited by the two vertical carinae on the lower face ( Fig. 3f ), being almost the only species of Ceroptres with this trait, except for C. ensiger and C. frondosae ; however, C. ensiger has the mesopleuron anteriorly alutaceous ( Fig. 6d ) and C. frondosae has different POL/OOL and OOL/diameter of lateral ocelli ratios as stated above.

Brief redescription. Apart from the morphological traits mentioned in the diagnosis section, C. cornigera is also characterized by having female antenna 12-segmented and filiform, male antenna 15-segmented and filiform ( Fig. 6a ); vertical carinae on the lower face incomplete, running from inner ventral margin of the toruli almost 2/3 of the lower face length and delimiting a depressed area that is bulged medially, forming a medial ridge ( Fig. 3e, f ); mesoscutum strongly coriaceous with weak discontinuous transversal elements ( Fig. 6b ); notauli almost complete, faint in the anterior 1/3 or before reaching the pronotal margin; median groove visible at most in the posterior 1/3 of the mesoscutum; mesoscutellum ( Fig. 6b ) densely but weakly wrinkled, more strongly wrinkled laterally and posteriorly, interspaces strongly coriaceous; third metasomal tergum with an inconspicuous posterodorsal patch of micropunctures and subsequent terga very finely punctate; radial cell 2.7 times as long as wide; body mainly black. For more details on the morphology of this species, consult Melika & Buss (2002) and the remarks section of this species (see below).

Distribution. USA. Lexington, state of Kentucky ( Melika & Buss 2002).

Biology. Reared from stem and leaf galls of the asexual and sexual generations of Callirhytis quercuscornigera (Osten-Sacken, 1862) ( Melika & Buss 2002) respectively, which associates with Quercus palustris Muenchh. (Lobatae section) and other red oaks ( Burks 1979; Melika & Buss 2002).

Remarks. Ceroptres cornigera was originally described from 18♂ and 18♀ ( Melika & Buss 2002: 629). We examined 3♀ and 5♂ deposited in USNM, including the holotype. According to G. Melika (pers. comm.), no mor- phological differences have been observed between specimens obtained from sexual and asexual galls.

Ceroptres cornigera was characterized by Melika & Buss (2002: 626); however, after studying its type material, we found some inconsistencies in the original description, and especially in the illustrations provided to characterize the species: (i) vertical carinae on the lower face are narrow and curved outwards in their distal half according to the illustrations, but in the type material examined these carinae are somewhat broad and straight, not reaching the oral fovea; (ii) the specimens examined have a median ridge between the two vertical carinae ( Fig. 3f ), which is not represented in the original illustrations nor commented on in the description; (iii) genae are expanded behind compound eyes in the original illustrations, but this trait has been exaggerated since genae are from very slightly to not expanded in the specimens examined ( Fig. 3e ); (iv) lastly, the mesoscutellum has a medial ridge between the scutellar foveae that reaches the mid of the mesoscutellum according to the original illustrations, but this ridge is absent in the specimens examined ( Fig. 6b ). Furthermore, POL:OOL:LOL and OOL/diameter lateral ocelli relations are not commented on in the original description.

Ceroptres cornigera is morphologically almost identical to C. frondosae Ashmead, 1896 , the few differences have already been commented on above (see the diagnosis of C. cornigera ). Ceroptres cornigera was obtained both from leaf (sexual) and stem (asexual) galls, while C. frondosae emerged from galls on axillary leaf-buds (see the biology section of C. frondosae ), which could correspond to the sexual form of the gall maker; also, these species were described from adjacent states (Kentucky and Missouri, respectively). However, both specimens of C. cornigera obtained from sexual galls and those obtained from asexual galls of Callirhytis quercuscornigera have the same ocellar ratios as the type material examined (all obtained from asexual galls) and also according to G. Melika (who measured specimens obtained from sexual galls, pers. comm.), thus suggesting this species is distinct from C. frondosae . Therefore, we here consider that C. frondosae and C. cornigera are different species, even though we do not rule out the possibility that they may be the same species and that the differences observed are indicative of intraspecific variation.

Figures

FIGURE 3. Female faces of valid species of Ceroptres: a) C. catesbaei (type); b) C. cerri; c) C. clavicornis; d) C. confertus (type); e) C. cornigera (type); f) detail of the median ridge in the lower face of C. cornigera; g) head of C. cornigera in dorsal view; h) C. ensiger; i) C. frondosae (type); j) detail of the median ridge in the lower face of C. frondosae; k) head of C. frondosae in dorsal view.

FIGURE 6. a) Ceroptres cornigera lateral and b) dorsal habitus (type); c) C. ensiger lateral habitus, d) detail of mesopleuron and e) dorsal habitus (type); f) C. frondosae lateral and g) dorsal habitus (type); h) head and mesosoma of C. kovalevi in lateral view, i) lateral metasoma and j) head and mesosoma in dorsal view (type).