Cheverella Landry, 2011

Landry, Bernard, Roque-Albelo, Lazaro & Hayden, James, 2011, A new genus and species of Spilomelinae (Lepidoptera, Pyralidae) from the Galapagos Islands, Ecuador, Revue suisse de Zoologie 118 (4), pp. 639-649 : 640-645

Cheverella Landry gen. n. Figs 1–8

Type species: Cheverella galapagensis sp. n.

Gender: feminine.

DIAGNOSIS: Cheverella can be separated from the other genera of Spilomelinae by two apomorphies of the male genitalia, i.e. the reduced uncus and the presence of

Cheverella galapagensis Landry , sp. n. (1) Holotype (CNC). (2) Darker coloured female paratype (MHNG).

setose pads on anterodorsal extensions of the valva mediobasally, and the clearly circumscribed corpus bursae with a short, spine-like signum in the female. Choristostigma Warren, a mainly North American genus with nine species, also has a reduced uncus and setose pads on a transtilla or extensions of the valva as in Cheverella ( C. elegantalis Warren and C. plumbosignalis (Fernald) examined), but its valva is more narrow and it has a short, setose projection at base of costa. The female genitalia of Choristostigma ( C. plumbosignalis (Fernald) examined) differ more strongly in that the wide ductus bursae has a large colliculum, the papillae anales are elongate rather than triangular, and the signum is very large, oval, and with multiple spines that are 4-5 X longer than their basal width and irregularly distributed.

DESCRIPTION: Head ( Fig. 3 ) with antennae filiform, slightly thinner in female, reaching almost 2/3 of length of forewing, with dense, short ciliation ventrally, with single short seta arising from scale-coated dorsal edge near middle of first 12 flagellomere approximately, with last flagellomere terminating into distinct sensillum styloconicum; with ocelli; without chaetosemata; maxillary palpus very short; labial palpus curved upward at about half right angle, reaching slightly above eye.

Forewing rather narrow, 2.4 X longer than largest width. Frenulum simple in male, with 2 acanthae in female. Retinaculum a short bunch of scales below cubital stem; male without frenulum hook. Wing venation (n=1) (Fig. 4): Forewing Sc, R1, and R2 free, latter from before upper angle of cell; R3 and R4 stalked for most of length, stemming from upper angle of cell; R5, M1-3, and CuA1-2 veins free; M1 and M2 well separated at base; M3 from lower angle of cell; 1A+2A clear; 3A faintly indicated. Hindwing with Sc+R1 connected with Rs from 1/2 to 3/4; M1-3, and CuA1-2 veins free; M1 and M2 well separated at base; M2, M3 and CuA1 stemming from lower angle of cell; anal veins clearly distinct. Abdomen: Male intersegmental membrane VIII-IX without associated sclerites or hair-like scales. Sternum VIII broadly sclerotized at base, with short median extension and long, thin lateral extensions reaching apex; tergum VIII with broad sclerotized band along whole segment medially. Female segment VII well sclerotized, narrower and longer than preceding segment, with tergum a large quadrangular plate. Tympanal organs (n=6) (Fig. 5): Tergo-sternal sclerite with broadly rounded, deeply concave ventral margin. Tympanum plane almost at right angle from sternal plane. Tympanic frame slightly projecting ventrad of margin of segment. Tympanic crest short, situated slightly anterad of middle. Tympanic drum short, slightly longer than wide, extending anterad to base of bridge. Transverse ridge slightly concave medially, without tympanic pockets, or unapparent, blending with surface of sternum. Tympanic bridge about 1/3 length of drums. Praecinctorium only slightly bilobed.

Male genitalia (n=3) (Figs 6, 7). Tegumen with wide median ridge, narrowly extended laterally at apex, widened at base and narrowly connected with lateral ridges; area between median and lateral ridges more thinly sclerotized, slightly bulged and with scale sockets, as opposed to bare ridges. Uncus reduced, mostly thinly sclerotised, rounded, apically setose, occasionally with very short median depression dorsally; ventral margin more thickly sclerotized, occasionally with very tiny point medially. Short arms of gnathos (sensu Solis & Metz, 2011) fused with narrow apicolateral ridges of tegumen, narrowly triangular, not connecting medially. Dorsal articulation of valva with vinculum of adjacent type (see Solis & Maes, 2003). Costa of valva with medially directed projection posterad of dorsal articulation of valva with vinculum; projections not connected medially and supporting rounded setose pads ventrally. Valva short, narrowing to half basal width near middle, apically rounded, with digit-like, mediodorsally recurved projection (sella) medially between pair of ridges, with shallow rounded cavity ventrad of sella, with long, abundant setation on basal part of sella dorsally. Juxta a thin, elongate plate with lobed ventral and apical margins, with short wing-like extensions laterally before middle. Vinculum shorter than tegumen + uncus, narrow, with anterior end curved upward, apically blunt in lateral view. Phallus short, stout, without pronounced coecum penis; vesica with bunch of about 20 short, slender cornuti.

Female genitalia (n=3) (Fig. 8). Papillae anales simple, rounded, setose, unconnected dorsally, with straight sclerotized band at base. Apophyses posteriores straight, reaching middle of segment VIII. Latter with well sclerotized plates laterally, sparsely setose, expanding apicoventrally toward midline, but medially not connected, dorsally approximate on distal half and fused on proximal half. Apophyses anteriores slightly curved and longer than posterior ones, not quite reaching middle of segment VII. Lamella postvaginalis triangular, located at base and between apical ventral extensions of sclerotized plates of segment VIII. Ostium bursae at bottom of cup-like, thinly sclerotized antrum. Ductus bursae with girth about 1/3 width of middle of antrum, more or less ridged on distal half, proximal half gradually expanding, without colliculum. Ductus seminalis arising subdistally, at slightly less than 1/3 of length of ductus bursae from ostium. Corpus bursae circular, with one small, spine-like signum ventrally near distal end.

ETYMOLOGY: The name is derived from a frequent interjection heard in Ecuador, chévere, which means great, nice, or cool. The unusual maculation of the moth prompted this interjection, or a synonym, to me and others who examined it. This type of maculation is found in another species of Galapagos Spilomelinae, but not in any other members of this subfamily as far as we know .

BIOLOGY: The caterpillar of Cheverella galapagensis is a borer in stems of

Tournefortia pubescens Hook. f. ( Boraginaceae ). One moth was reared by Lazaro Roque-Albelo in 1999, from a plant growing on the Barranco, just behind the Charles Darwin Research Station on Santa Cruz Island. This endemic species of Tournefortia is known to contain pyrrolizidine alkaloids (Roque-Albelo et al., 2009). These are known to protect Utetheisa connerorum Roque-Albelo & Landry ( Lepidoptera , Arctiidae ) (formerly mostly known as U. galapagensis (Wallengren)) moths from being consumed by Eustala (Araneidae) spiders ( Garrett et al., 2008). Whether or not Cheverella also stores pyrrolizidine alkaloids remains to be discovered.

REMARKS: The medially directed projections arising from the costal edge of the valvae posterad from the dorsal articulations of the valvae with the vinculum are not called a transtilla as the definition of this structure is restricted to ‘the [dorsal] sclerotisation of the diaphragma’ (Solis & Maes, 2003).

SYSTEMATIC POSITION: The current classification of Neotropical Spilomelinae ( Munroe, 1995) recognizes 14 groups of genera and 51 unplaced genera. Unfortunately, Munroe did not provide diagnostic characters to support his groups, and there is no classification available for any other Spilomelinae fauna. Therefore, we examined representatives of Munroe's generic groups to find apparently diagnostic character combinations, and we comment on their validity and applicability to the newly described genus. Cheverella was found to have affinities with the Hydriris and the Siga groups of Munroe (1995). With the Hydriris group, Cheverella shares a reduced uncus without robust bifid spines and the presence of setose pads in the vicinity of the transtilla in Choristostigma Warren. However, in the other genera of the group, the setose pads are in different positions (on the costa in Geshna Dyar, on the tegumen in Hydriris Meyrick) or absent in Nehydriris Munroe. Most of the members of this group share tufts of setae at or around the base of the costa of the valva, but these setae are lacking in Cheverella and Nehydriris, and the female genitalia vary among the three genera for which they are known. The Diagnosis above explains some of the differences between the female genitalia of Cheverella and Choristostigma. Those of Geshna show a poorly differentiated, elongate corpus bursae without signum, while those of Hydriris have a very short ductus bursae and an elongate corpus bursae with an appendix bursae and with two large signa showing about 12 long, thin and curved projections. The labial palpi are variable. They are upturned in Hydriris and Geshna but porrect with downturned apical meron in Choristostigma, so the upwardly directed palpi of Cheverella fit in this range. Hence, there is no clear indication that the Hydriris group is monophyletic as presently constituted.

The Siga group of Munroe (1995) comprises large, robust-bodied Neotropical moths. Our concept of the group is here informed by our addition of Loxomorpha Amsel and Maracayia Amsel, because they share the same structural characters and known larval habits, despite their much smaller size. So defined, the Siga group varies greatly in maculation, but the forewing postmedial line is usually roundly concave on the anal fold. The labial palpi are short or obliquely ascending with a short apical meron. The male genitalia are robust with a moderately inflated sacculus and wellsclerotized costa, and the saccus is absent or weakly developed. The sella is aciculate in most member taxa (as in the Hydriris group), but it is quadrate in some (Cirrhocephalina Munroe) or with a basal process (Laniifera Hampson). The uncus is bifid with a short stalk or none at all (with the two uncus arms arising from the tegumen separately), and the apices of the uncus are armed with robust, bifid chaetae. In the female genitalia, where known, the ostium bursae is strongly sclerotized and shaped like a funnel or pitcher plant, and the corpus bursae lacks a signum. Known larvae (Laniifera, Beebea Schaus, Loxomorpha, Maracayia) are all borers in Cactaceae. Among these characters, Cheverella shares the straight and obliquely ascending labial palpi, robust genitalia with inflated sacculus, and the distally quadrate sella of some members. The breadth of the ostium bursae is similar, but it is only weakly sclerotized in Cheverella . The absence of an uncus, bifid or otherwise, would be explained as derived from the reduced bilobate condition seen in Zeuzerobotys Munroe. Although Cheverella is much smaller than most, it is comparable in size to Loxomorpha species. The black and white wing coloration is shared with Zeuzerobotys.

The following characters are shared by the two groups and Cheverella , so although they do not favor placement in either group, they exclude Cheverella from many other spilomeline groups. The valve costa is straight or slightly concave, and the apex of the valve is rounded but attenuate (narrower than the valve width across the costa). The valve sella originates variably from the costal half of the valve or near middle of the valve. The hindwing maculation is nearly absent, and the praecinctorium is weakly (not strongly) bilobed.

(4) Cheverella galapagensis Landry , sp. n. Wing venation of paratype male (MHNG). (5) Cheverella galapagensis Landry , sp. n. Tympanal organs of paratype male, without praecinctorium (MHNG).

Other characters were examined (tympanal organs, venation) but were found to be either invariant or so variable as to be uninformative of relationships at the level of generic group. The diagnostic characters in these groups (and others) should be evaluated in a phylogenetic context to determine their influence and to help uncover the relationships of Cheverella .

The biogeographic relationships of Cheverella are ambiguous but suggest testable hypotheses. The Hydriris group includes one Neotropical member (Nehydriris of southern Brazil) and the cosmopolitan Hydriris; the other members range to the southern Nearctic. As far as known, the Siga group is exclusively Neotropical to southern Nearctic, with members distributed in many subregions. Among these, Beebea guglielmi Schaus is endemic to the Galapagos Islands, so despite the great difference in body size and maculation, the possibility of a close relationship should be considered. If Cheverella belongs to the Siga group, two hypotheses suggest themselves. A close relationship with Beebea would support rapid evolutionary divergence in body size and wing maculation, which might be expected on the Galapagos. Conversely, a closer relationship with a mainland taxon would suggest more than one dispersal event to the islands or a more complex biogeographic scenario. If Cheverella is more related to some other spilomeline group, similarly intriguing hypotheses may present themselves. Cladistic and biogeographic analyses of Spilomelinae are greatly needed for choosing among these alternative hypotheses.

Figures

FIG. 3 Cheverella galapagensis Landry, sp. n. Head of paratype female from Santa Cruz Island (CNC).