Gymelloxes terea ( Schaus, 1892 )

Grehan, John R. & Mielke, Carlos G. C., 2017, Re-characterization of Gymelloxes with a re-description of Gymelloxes terea from Central America (Lepidoptera: Hepialidae), Zootaxa 4363 (3) : -

Gymelloxes terea ( Schaus, 1892)

Diagnosis. Gymelloxes terea is easily distinguished from all other Hepialidae by the unique shape and orientation of the tergal lobes of the male genitalia. The male can be determinated by removing scales from the genitalic region and observing the rounded, rim-like margins of the pseudotegumen ( Figs 14, 15 ). The taxonomic significance of the lamella antevaginalis morphology cannot be assessed because the females of most Hepialidae of the tergal lobe clade have not yet been described.

Redescription. Male ( Figs 1–3, 6 , 7, 9, 12, 14–18). Wing dimensions – mean values (n=5): Wingspan 50 mm (45– 55 mm); FW length: 23 mm (20–26 mm), width: 10 mm (8–11 m), ratio 2.3:1; HW length: 19 mm (16–21 mm), width: 9 mm, ratio 2:1.

Head: Antenna bipectinate, 28–32 antennomeres; dorsal surface with lamellate scales, dorsal apex with tuft of longer narrow scales ( Fig. 6 ); flagellum inner surface carpeted with sensilla trichodea, outer surface with scattered sensilla chaetica. Eyes prominent. Maxillary palpus robust, double in size as the labial palpus, the latter characterized by one stout and rounded palpomere; covering scales short, reddish brown. Vestiture with erect orange-brown scales over vertex, frons, and mouthparts; intra antenna-ocular scales short, indistinct from vertex scales.

Thorax: reddish-brown; posterior dorsal and lateral scales of the mesothorax not covering metathorax anteriorly; scutum III iridescent dark brown free of long scales other than posterior and medial regions, covered in minute striations or prone microtrichia. Wing venation ‘hepialine’ ( Dumbleton 1966) with (Rs1+Rs2)+ Rs3 not stalked at base and Rs3 joining Rs4 basal to cross vein r-m; narrow spacing between Sc and R towards apex, particularly on the hindwing (Fig. 7); Sc1 present; distance between costal margin and Sc widest at humeral vein and narrowing towards apex. FW costal margin almost straight, outer and posterior margins convex without sharp anal angle. FW dorsal ground colour pale greyish brown with darker markings of grey or reddish brown; brown spots between veins edged with white and greyish scales, forming broken transverse bands between CuA2 and costal and outer margins, and forming in triangular region over discal area, and premarginal and marginal transverse bands; central brown spot in discal cell between Rs and M2 bordered basally and distally by pale greyish brown spots; about six greyish black bands between C and Sc/R and dark greyish black line basal to CuA2 and basal edge of the premarginal band; silvery white or greyish white stigma at junction of r-m and M1, and distally along M1 near junction; cubital region marked with pale indistinct transverse patches of greyish black and yellowish brown. FW ventral ground color yellowish brown, veins pale yellowish brown, partially translucent dorsal pattern visible; Sc lined with row of posterior projecting yellowish-brown scales characterized as androconial hairs ( Viette 1952); costal pocket with longitudinal ribbing over anterior surface. HW dorsally pale yellowish brown; discal cells weakly scaled, translucent; 1A and 2A extends to anal margin. Ventral HW yellowish brown with pale yellowish brown veins. Legs: typically hepialid with the midleg being longest and the metaleg being shortest (and in this case only 70% of the foreleg length), and the femur of the midleg also being longer than in the other legs; epiphysis absent, metatibial gland absent, mesoleg longest, particularly femur and tibia, fore/meso/meta leg ratio 1:1.2:0.7 (Fig. 9).

Abdomen: yellowish brown; tergum I membranous, broadly rectangular, anterior-posteriorly short, length/width ratio 1:3.4; tergum II rectangular with strongly developed lateral ridge with anterior extension along anterior edge of lateral tuberculate plate, almost reaching anterior ridge of tergum II, latter not fused across dorsal median (Fig. 11); sternum II rectangular, medial anterior margin flat, lateral anterior arms of sternum II obliquely angled to central anterior margin, lateral edges of arms with well developed ridge, slightly curved; tergosternal junction (Fig. 11) comprising a broad, subrectangular intermediate zone with fused tergosternal bar which narrows to ventral apex at junction with lateral arm of SII. Tergal knob present at posterior margin of intermediate zone. Anterior margin with anterior break almost enclosed. Tergal brace short, right angled, curving from lateral to dorsal brace. Sinus sclerotized, sclerotization extending to plural region between tergal knob and curving dorsally to anterior lateral brace of tergum II, connection between dorsal tergal brace and anterior ridge of tergum II lightly sclerotized; tergum VII slightly narrower and longer than tergum VI, tergum VIII with convex posterior margin. Sternum VII square, sternum VIII more strongly sclerotized than other abdominal segments, trapezoid, wider posteriorly, slightly concave antero-laterally, slight lateral concavity of posterior margin.

FIGURES 7−13. Gymelloxes terea . 7−8. Venation: 7, male; 8. female venation; 9−10. Legs: 9, male; 10, female (F250). 11−13. Abdomen: 11, tergosternal connection, lateral view; 12, male, upper dorsal, lower ventral view (M249); 13, female, upper dorsal, lower ventral view (F250). Scale bar = 1 mm for Figs 12 and 13.

Male genitalia ( Fig. 14–18 ). Tegumen indistinct, likely fused to pseudotegumen. Saccus U-shaped, anterior margin broad, anterior and lateral margins projecting dorsally to form a vertical wall or shelf, posterior margin with two short, apically flat, peg-like projections extending posteriorly, curving slightly medially. Tergal lobes sclerotized, digitiform, projected posteriorly, width narrowing to rounded apex, and fused to pseudotegumen. Pseudotegumen ventral apex strongly sclerotized, each plate thinly separated at apex, margins either side of phallus rounded, slightly curved laterally forming appearance of an inflated rim; lateral pseudotegumen projects anteriorly and internal to the apodemal suture to form an semi-ovoid internal lateral plate ( Viette 1952) between the dorsal spine and pseudotegumen-saccus junction. Valva narrowly spatulate, inner surface densely setose, apex rounded. Fultura inferior sclerotized, rectangular, wider than long, lateral and posterior margins slightly concave; fultura superior partially sclerotized in two rows of two irregular shaped blotches. Phallus membranous except for distal region covered with numerous spicules.

Female ( Figs 4, 5 , 8, 10, 13, 19–21): Wingspan 60 mm; FW length: 30 mm, width: 11 mm, ratio 2.7:1; HW length: 25 mm, width: 10 mm, ratio 2.5:1.

Head. Antennae (flagellum missing). Eyes similar size to male. Mouthparts: single segmented labial palp, short and rounded.

Thorax: yellowish brown; posterior dorsal and lateral scales of the mesothorax not covering metathorax anteriorly; scutum III iridescent brown free of scales other than posterior and medial regions. Wing venation and color pattern as for male other than presence of 3A on the hindwing (Fig. 8). Missing HW cross vein M2-M3, and Rs3 terminating before outer margin considered likely to be an artefact as these features are not applicable to female specimens of G. prosopus (Mielke, personal observation). Wing color pattern as for male. Legs: foreleg missing, mesoleg length similar proportion to metaleg as in male (Fig. 10); abdominal sclerites similar to male except for broad posterior tergum subequal in length to sternum VII and VIII that either represents a fusion of the last two tergites or the loss of tergum VIII, and sternum VIII rectangular and similar in size to sternum VII (Fig. 13).

Female genitalia ( Figs 19–21 ). Longer than wide, tergum IX (= dorsal plates of Nielsen & Kristensen 1989) posterior margin an inverted U with narrow and setose region (anal papillae) from dorsal median to near junction with lamella antevaginalis. Subanal plate trapezoid, lateral surface slightly concave. Lamella antevaginalis broad, longer towards median, setose dorsally, internal surface forming a sclerotized plate, narrowing slightly towards dorsal margin, projecting above dorsal margin of lamella antevaginalis ( Fig. 19 ). Antrum forms invagination above entrance to ductus, with ventral floor meeting ductus at a sclerotized patch. Ductus bursae forming a narrow tube about two thirds length of corpus bursae with a sinus ventrally at its base; corpus bursae an elongate teardrop shape, widest near junction with ductus bursae ( Fig. 21 ).

Distribution. Viette (1952) described the distribution as through Central America to Venezuela at least to Maracay. The type (USNM) is from Paso de San Juan near Santa Cruz, Mexico ( Schaus 1892). The specimens examined by Viette (1952) confirm this species from Nicaragua, Panama and western Venezuela.

Phenology. April-May ( Nicaragua), May-July ( Venezuela). So, before or at the beginning of the rainy season.

Host plant. Unknown.

Taxonomic notes. Assignment of the male specimens to G. terea was made by a visual comparison with the dissection by Viette (1952) ( Fig. 18 ) and the lectotype specimen ( Fig. 3 ), here designated since Schaus’s description does not indicate the presence of one or more syntypes. Viette’s (1952) dissection, for a specimen from Paso de San Juan, Veracruz, Mexico, is slide mounted and laterally compressed which limits the ability to compare all details with fresh material (hepialid genitalia have a strongly three dimensional structure that is often severely distorted in slide mounts which often limits or even eliminates their taxonomic utility). There are some very slight differences in the shape of the saccus, pseudotegumen, and the dorsal lobes. The latter appear to be slightly broader towards the apex in the lectotype whereas the Nicaragua specimen is more tapered). Whether these slight differences may indicate a species level distinction or fall under the intraspecific variation will require extensive sampling of males, and preferably the inclusion of more females, as well as the study of ecological and biological characteristics to confirm the presence of any, as yet, cryptic species.

Males of G. terea , as currently defined, are easily distinguished from all other Hepialidae by the unique shape and orientation of the dorsal projections of the male genitalia. The male can also be distinguished by removing scales from the genitalic region and observing the rounded, rim-like margins of the pseudotegumen ( Figs 14, 15 ). The general systematic and taxonomic significance of the lamella antevaginalis morphology, the female cannot be assessed as the females of most cibyrine Hepialidae have not yet been described.

Here in this paper we re-described the species G. terea based on the type specimen (the lectotype) and additional studied specimen which are conspecific to G. terea . To clarify full synonymy of this species is beyond the scope of the present publication. Future study will clarify whether the specimens attributed to G. prosopus from Panama and Colombia ( Mielke & Grehan 2012) as well as the specimens attributed to G. terea from Venezuela (specimens housed at ZSBS) are conspecific to G. terea following this present species delineation or they belong to a separate distinct species.

Figures

FIGURES14−21.Gymelloxesterea. 14−18.Malegenitalia(M249):14, lateralhabitus view;15, lateralviewwithphallus everted;16, postero-ventral view (M249); 17, antero-ventral view (M249); 18, male lectotype (type 18603, USNM); 19−21.Female genitalia:19, postero-ventral view(F250); 20, lateral view (F250);21, Ductus and corpus bursae,lateral view (F250).Scale bar= 1 mm.

FIGURES 1−6. Gymelloxes terea. 1, male, dorsal view (JRG); 2, male, ventral view; 3, male lectotype, dorsal view (type 18603, USNM); 4, female, dorsalview (F250, CGCM);5,female,ventral view; 6, male antenna,dorsal view.Scalebar = 1 cm.