Mesolia christinae, Landry & Léger, 2024

Mesolia christinae sp. nov.

Figs 1-4 View Figs 1-8 , 37-39 View Figs 37-39 , 51, 52 View Figs 51-55

Material examined: Holotype: ♀, ‘ ECU[ADOR]., GALAPAGOS | Genovesa , Bahia | Darwin, 26.iii.1992 | M[ercury]V[apour]L[ight], leg [it]. B. Landry’; ‘HOLOTYPE | Mesolia | christinae | Landry & Léger’; ‘ MHNG | ENTO | 00085748 ’. Deposited in MHNG .

Paratypes: 18 ♂, 40 ♀ from the Galápagos Islands. – Genovesa : 3 ♂, 1 ♀, south side of island, 200 yards from beach, 4-6.ii.1967, in flight trap among Bursera graveolans (I.L. Wiggins) ; 6 ♂ (one dissected, MHNG-ENTO-85551 ), 13 ♀ (one dissected, MHNG-ENTO-85552 ), Bahia Darwin, 10.iii.1992, MVL (B. Landry); 1 ♂, 23 ♀ (one dissected, MHNG-ENTO-85555 ), with same data as holotype; 8 ♂ (one dissected, MHNG-ENTO-85536 ), 3 ♀ (one dissected, MHNG-ENTO-85537 ), same data as holotype except 26.iii.1992. Deposited in CAS, CDRS, and MHNG.

Additional material examined: 20 ♂, 29 ♀ from the Galápagos Islands. – Fernandina : 2 ♀ (dissected, MHNG-ENTO-85558), Cabo Douglas, GPS: S 00°18.269’, W 091°39.098’, 9.ii.2005, u[ltra]v[iolet] l[ight] (B. Landry, P. Schmitz); GoogleMaps 1 ♂, SW side, GPS: 352 m elev., S 00°20.503’, W 091°36.969’, 10.ii.2005, uvl (B. Landry, P. Schmitz); GoogleMaps 1 ♂, Punta Espinosa, 12.v.1992, M[ercury]V[apour]L[ight] (B. Landry). – Floreana : 1 ♀, close to Las Palmas, GPS: 154 m elev., S 01°17.049’, W 090°28.305’, 15.iv.2004, uvl (P. Schmitz); GoogleMaps 1 ♂ (dissected, MHNG-ENTO-85550), 6 ♀ (one dissected, slide MHNG-ENTO-85557), Punta Cormoran, 21.iv.1992, MVL (B. Landry). – Genovesa : 7 ♂, 3 ♀, south side of island, 200 yards from beach, 4-6.ii.1967, in flight trap among Bursera graveolans (I.L. Wiggins) . – Isabela : 1 ♀, V[olcan]. Darwin, campamento base, 1.iii.2000, Malaise trap (L. Roque, n° 2000-03); 1 ♂, Volcan Darwin, 200 m s[obre el] n[ivel del]m[ar] [above sea level], 2.iii.2000, uvlw[hite]l[ight] (L. Roque, n° 2000-05); 1 ♂, 9 ♀, Tagus Cove, alt[itude]. ± 10 m, 22-23.iii.1970, at 15 W uv blacklight (R. Silberglied); 1 ♀, V. Alcedo, 200 m [elev.], arida alta [zone], 12.iv.2001, luz fluorescente [fluorescent light] (L. Roque, n° 2001-06); 1 ♂, 1 ♀, [Volcan] Alcedo, lado [side] NE, 200 m [elev.], camp arida alta, 14.iv.2002, uvl (B. Landry, L. Roque); 1 ♂ (dissected, slide MHNG-ENTO-85559), 2 ♀, Alcedo, lado NE, low arid zone, bosq[ue]. palo santo [forest], 18.iv.2002, uvl (B. Landry, L. Roque). – Marchena: 1 ♂ (dissected, MHNG-ENTO-85553), 1 ♀, 12.iii.1992, MVL (B. Landry). – Pinta: 1 ♂ (dissected, slide MHNG-ENTO-85560), ± 50 m elev., 20.iii.1992, MVL (B. Landry); 1 ♀, 630 m [elev.], xi.1970, B[ritish].M[useum]. 1971-79, Ref[erence]. No. L.100 (collector unknown). – Plaza Sur : 1 ♂, 14 m. elev., S 00°34.982’, W 090°09.936’, 15.iv.2006, uvl (P. Schmitz). GoogleMaps – Santa Fe: 1 ♀, tourist trail, 28.v.1992, MVL (B. Landry). – Santiago: 1 ♂, N end Bahia James, 1-2.ii.1967 (I.L. Wiggins); 2 ♂ (dissected, MHNG-ENTO-85554 and 85561), Cerro Inn, 28.iii.1992 MVL (B. Landry). Deposited in CAS, CDRS, MCZ, MHNG, NHMUK .

Etymology: This species is dedicated to MHNG artist Christina Lehmann-Graber for her outstanding work on BL’s illustrations of this publication and some others.

Diagnosis: In the Galápagos Islands this species is easily separated from other moths by virtue of its size, narrow forewings, long, porrect labial palpi, and forewing white subterminal line that zigzags from the dorsal margin until the median sector where it is directed outward to almost reach the outer margin and then diverges at 90° to reach the costal margin at distal 1/6. Naturally poorly marked specimens do resemble poorly marked specimens of La galapagensis sp. nov. ( Fig. 18 View Figs 15-20 ) by virtue of their similar ground colour, narrow forewings and long, porrect labial palpi, but in M. christinae sp. nov. the forewing apex is rounded whereas it is pointed in La galapagensis sp. nov. Poorly marked, dark-winged specimens of Parapediasia galapagensi s sp. nov. ( Fig. 36 View Figs 29-36 ) are also similar, but specimens of the latter always retain a simple subterminal line and their hindwing is white. With respect to the other Neotropical species of Mesolia , M. christinae sp. nov. is most similar to M. nipis ( Dyar, 1914) , described from Mexico, Sierra de Guerrero. However, in M. nipis , even though the holotype is in poor condition, one can see that it has no markings at base until the postmedian line, the outer margin is conspicuously produced at M1-M2, the costa is white between the postmedian and subterminal lines, and there are two prominent black dashes in the M3-CuA sector abutting the subterminal line and ending before the outer margin in a white patch along the outer margin.

Description: Male (n=38) ( Fig. 1 View Figs 1-8 ). Head with frons produced, pointed, with vestiture mostly short scaled, white ventrally, brown dorsally; with longer scales laterally over eye white, between antennal bases mostly brown, on occiput and vertex mostly white laterally, brown medially. Antenna laminate with widest flagellomeres about 10% wider than long; vestiture on scape and pedicel white ventrally, on flagellomeres with basal row of scales dark brown and distal row half white and half dark brown on basal 10 flagellomeres, with white replaced by greyish brown on subsequent flagellomeres. Maxillary palpus at base brown laterally and white medially, apically white to greyish white. Labial palpus white on most of first palpomere, white on second ventrally and medially, brown laterally on second and on third. Haustellum white. Thorax mixed white and brown, most often white (or paler) at edges and apex of tegula, beneath tegula, medially on patagium, and as transverse band at junction of mesoscutum and mesoscutellum. Forewing length: 6.0- 9.0 mm (holotype: 7.9 mm); wingspan: 13.0-19.0 mm (holotype: 17.7 mm). Wings with colour and pattern as illustrated ( Fig. 1 View Figs 1-8 ). Prothoracic leg coxa and trochanter greyish brown, more or less mottled with white; femur greyish brown with white on ventral edge and medially; tibia white, or at least paler at base and apex, brown in between; tarsomeres I-V as tibia, with paler colour at base less conspicuous or absent on tarsomeres III-V. Mesothoracic leg coxa and trochanter white, tinged with pale brown; femur white to pale greyish brown; tibia pale greyish brown laterally except for white base and apex, white medially; tarsomere I dark greyish brown laterally between white base and apex; tarsomere II white at base and apex, laterally greyish brown in between, sometimes straw-coloured medially; tarsomeres III-V as tarsomere II, but without white at base usually. Metathoracic leg coxa and trochanter as mesothoracic leg; femur white with pale greyish brown apically; tibia mostly white, with pale greyish brown dorsally, sometimes only at apex; tarsomeres as mesothoracic leg. Abdomen dorsally greyish brown, often darker on first tergite, ventrally paler, white to pale greyish brown. Tergum VIII ( Fig. 37 View Figs 37-39 ) with sclerotization as shown. Intersegmental membrane VII-VIII with one digit-like coremata on each side ( Fig. 39a View Figs 37-39 ), about 1/3 as long as valva, slightly variable in width.

Male genitalia (n=9) ( Figs 38, 39 View Figs 37-39 ). Uncus strong, broadly curved, with dorsodistal crest less thickly sclerotized, with short to medium length setae laterally from about 1/3 until 5/6 of length and dorsally on crest, dorsal edge of crest serrated on distal half, apex laterally compressed. Anal tube ventrally sclerotized as short and narrow plate. Gnathos short, with arms of medium width, more thickly sclerotized on proximal edge, joined at 2/3 to form short, upturned point, with few spinules dorsally along midline in curve of distal section. Tegumen of medium size, with distal edge of lateral arms more thickly sclerotized. Juxta shield like, with apex blunt. Valva medium sized, with dorsal and ventral margins parallel at base until about 1/3 of length, ventral margin then bent upwards, apex broadly rounded, about as wide as half of basal width. Vinculum narrow, about twice as wide towards junction with tegumen arms, with proximal margin medially blunt or slightly concave. Pseudosaccus short, pear-shaped. Phallus straight, about 4/5 valva length, base with ventral and dorsal margins indented, slightly wider at apical ¼ and with more thickly sclerotized, longitudinal striae; vesica without cornuti.

Female (n=70) ( Figs 2-4 View Figs 1-8 ). Head with frons as male’s. Antenna simple, with white scaling on most flagellomeres more abundant than in males. Forewing length: 5.5- 9.5 mm (wingspan: 12.5-21.0 mm). Frenulum with 1 acantha. Wings with colours and pattern as illustrated, sometimes with markings less distinct than in males.

Female genitalia (n=7) ( Figs 51, 52 View Figs 51-55 ). Papillae anales of medium length and densely setose, shortly produced dorsally; narrow basal sclerite along ventral half narrowing and not connecting ventrally. Posterior apophyses straight, reaching basal margin of segment VIII. Tergite VIII sclerotized areas slightly longer than papillae anales, wider dorsally, unconnected ventrally. Anterior apophyses with short support bar diagonally positioned in segment VIII, with small subtriangular enlargement at basal 1/8, about 1/4 longer than posterior apophyses, straight until slight bend at 5/8, then gently curving. Ostium membranous, about half as wide as width of segment VIII. Ductus bursae wide, with smoothly sclerotized colliculum about 1/3 of whole length of ductus, otherwise simply membranous. Corpus bursae slightly longer than wide, about 1/4 longer than ductus bursae, without sclerotization.

Biology: The hostplant is unknown and the fact that some of the paratypes were collected “among Bursera graveolans ” does not reflect a direct host-plant association. A shrub or tree reaching 12 m in height, B. graveolans (Kunth) Triana & Planch. ( Burseraceae ) is a common feature of the arid zone of most islands and many islets of the Galápagos ( McMullen, 1999). No host plant is known for Mesolia species. The moths of M. christinae readily come to artificial lights at night.

Distribution: Presently known from the Galápagos islands of Fernandina, Floreana, Genovesa, Isabela, Marchena, Pinta, Plaza Sur , Santa Fé, and Santiago.

Remarks: Although altogether 108 specimens studied are assigned to this species, the type series is restricted to 59 specimens collected on Genovesa Island. This is because 10 more specimens available from Genovesa are too heavily damaged and, more significantly, the populations found on the other islands are insufficiently known. Specimens of these populations appear to be slightly larger on average than on Genovesa and also slightly warmer brown and with the forewing markings less distinct ( Figs 3, 4 View Figs 1-8 ), especially in females. In genitalia, two male paratypes dissected vary slightly in the width of the valva and in the shape of the anterior margin of the vinculum medially, which is convex in one specimen and straight in the other, with the pseudosaccus reaching beyond the anterior margin in the specimen with the convex margin and just reaching it in the specimen with the straight margin. Male genitalia variation also occurs in specimens from other islands such as a slightly thicker and shorter phallus in a specimen from Santiago Island, but not in another from the same island, a less strongly curved uncus as well as narrower valva at base compared to its apex in one specimen from Isabela Island, and a narrower tegumen and a longer and narrower phallus ( Fig. 39 View Figs 37-39 ) in a specimen from Floreana Island. In female genitalia no significant differences could be detected in the dissected specimens.