Cossidae of the Socotra Archipelago (Yemen)

Abstract The faunistic composition of the family Cossidae (Lepidoptera) of the Socotra Archipelago is revised. Five species are recognized, including two new species (Mormogystia brandstetteri and Meharia hackeri), and dubious identifications and records are discussed. Adults and genitalia are illustrated and bionomic details, DNA barcodes and a synonymic checklist for Socotran cossids are provided. A review of their distribution reveals that at least 80 percent of Socotra’s cossids are unique to the archipelago, which is renowned for its endemism. A checklist listing all the species from generas Meharia, Mormogystia, Aethalopteryx, Azygophleps, as well as the synonymy and distribution is provided.


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This paper results from a collaborative project "The Lepidoptera of Socotra Islands/ Yemen -an integrative study of the fauna for reconstruction of evolutionary scenarios and for determination of conservation needs", between the Zoologische Staatssammlung, (München, Germany), the Nature Research Centre (Vilnius, Lithuania) and Museum of Socotra Archipelago Conservation & Development Programme (Hadibo, Socotra, Yemen).
Socotra, which lies 240 km east of the Horn of Africa and 380 km south of the Arabian Peninsula, is a well-known source of material for biogeography and evolution studies -a living laboratory with a high degree of endemism. It was explored by both English (described by Hampson 1899) and Austrian (described by Rebel 1907) natural history expeditions just before the turn of the 20th century, but it remained effectively inaccessible during the 1900s due to its geographic isolation, extreme natural conditions and military concerns. Wranik's 1999 summary of existing natural history knowledge addressed Lepidoptera conservation issues of the Socotra Archipelago, but was based primarily on information gained during those earlier expeditions. Collaboration of one of us (AS) with the SCDP, collecting from late February to early March andNovember 2008, March 2009 and January provided new data contributing to the understanding of Socotra's Cossidae fauna.
The Socotra Archipelago consists of four islands with Socotra (130 kilometres in length and 30-40 kilometres in width) accounting for 95% of the archipelago's land mass. Socotra, regarded as one of the most alien looking places on earth, has three main geographical features: (1) narrow coastal plains, (2) a limestone plateau extending across most of the island with karst caves, deep valleys and steep escarpments from 300 to 700 m, and (3) the Haghier Mountains in the centre of the island, which rise to 1,519 m (Miller and Cope 1996) Socotra is a tropical desert with average highs between 27 o C and 34 o C and annual rainfall of only 130-170 mm. Rain is more intense in the higher mountains, which form the most important watershed and where many periodical watercourses run to the north and south. Permanent springs can also be found there, especially on the northern side. Otherwise, springs and streams are sporadic relying on rainfall. Climate conditions, rainfalls and major wind systems are dominated by seasonal monsoons of the Indian Ocean with most rain occurring during the Northern Hemisphere winter. The monsoon season causes strong winds and high seas, which cut off the island completely during the time of the southwest monsoon from May to September (Miller andCope 1996, Wranik 1999).
The Socotra Archipelago is thought to have been part of the Gondwana supercontinent before it detached during the Miocene. In Tertiary times, Socotra was separated as part of a fault block from the African-Arabic tectonic plate and was formed coincident with the Gulf of Aden. As a result of its extremely long isolation, Socotra is of major biogeographical interest and more than one third of all its plants and possibly animals are found nowhere else. Botanists rank Socotra's flora, including the extraordinary dragon´s blood tree Dracaena cinnabari, to be among the most important and endangered island floras of the world. It is generally suggested that the endemic plants and animals are relicts and descendants of ancient flora and fauna, which have survived since the Mesozoic era (Miller andCope 1996, Wranik 1999).
Socotra Archipelago fauna is composed of tropical-subtropical arboreal and eremic elements derived from African, Asian or south-Arabian and endemic origins (Wranik 1999). No comprehensive investigations of the insular fauna of Socotra are available and ambiguous taxonomic definitions have repressed faunistic analysis and development of species checklists. Wranik (1999) examined a limited number of groups including Odonata in which only one of 20 species is endemic and Saltatoria where over half of about 50 species are endemic. Wranik found Tenebrionidae to have the highest level of endemism: most of about 30 species are endemic, indicating a Somalarabic relationship, while others are may be relicts from a more ancient fauna already extinct on the mainland.
About 250 species of Lepidoptera are currently reported from Socotra in the literature including 30 species of Rhopalocera (Hacker 1999), 89 Noctuidae (Hacker and Saldaitis 2010), over 40 Pyralidae (Hacker 1999), 28 Geometridae (Hausmann 2009) and others from less studied groups. Rebel (1907) suggested that 1/3 of the Lepidoptera fauna of the Socotra Archipelago was endemic, with a dominance of Afrotropical relationships.
We present five Cossidae species from Socotra, excluding Eremocossus proleuca (Hampson, 1896) and Azygophleps inclusa (Walker, 1856) which were mistakenly attributed to Socotra by Hampson (1903), Rebel (1907) and Hacker (1999). E. proleuca which was erroneously synonymized by Wiltshire (1980) as E. reibellii (Oberthür, 1876) does not occur on Socotra but was probably confused with one of the two new Cossidae species described in this paper. Azygophleps inclusa is distributed only in tropical Africa and differs from the similar Azygophleps larseni which is distributed in the Arabian peninsula and Socotra island.

Diagnosis.
Mormogystia is distinguished from all other Cossidae genus by having large silvery areas on the forewing. Description. Medium sized, brightly coloured moths. Male antennae bipectinate with very short processes; female antennal pecten much reduced. Large silvery areas on the forewing forming fasciae make this the only Cossidae genus to have such a high contrast pattern. Hindwings are uniform.
Male genitalia. Uncus elongate, with tapering or rounded broad apex; arms of gnathos short, fused to form a medium-size gnathos densely covered with small spines; valvae shovel-shaped, with pronounced sacculus and a large triangular costal projection; transtilla projections short, thick and uncinate; juxta saddle-shaped, with long lateral projections directed upwards; saccus massive, semicircular; aedeagus short, straight, thick; vesica opening located dorsoapically, its edges with short, spiny processes; vesica without cornutus.
Remarks.This small genus includes four species distributed in north Africa, Levante, Arabian peninsula and Kenya    in M. brandstetteri uncus broad, apex of valvae form a straight angle; in M. reibellii and M. proleuca saccus rounded, apically without denticle, whereas in the new species saccus pointed, apically with a denticle; M. proleuca aedeagus at the basal end markedly narrowing, gradually widening towards apex; M. reibellii aedeagus of the same width from its middle to apex; in M. brandstetteri aedeagus widening at proximal end, gradually tapering towards apex. In the most closely related species, M. proleuca, the bursa is apically broader than basally (Fig. 28) unlike in the new species where the corpus bursae is significantly broader. Distribution. M. brandstetteri is endemic to the Socotra Archipelago while M. reibellii is distributed in North Africa and the northern part of the Arabian peninsula, M. proleuca is found in the southern part of the peninsula, and M. equatorialis is widespread in Kenya. Hampson (1903) and Rebel (1907) believed M. proleuca to be endemic to the Socotra Archipelago and later Hacker (1999) reported M. reibellii from Socotra, but the new species described herein was probably implied.
Molecular Analysis. While molecular results alone are insufficient to definitively separate M. brandstetteri from M. proleuca, they help corroborate the morphological evidence. Evolutionary distances using the Kimura two-parameter model for comparing four specimens of M. brandstetteri to four M. proleuca and to three M. reibellii specimens, was at least 1.55% and 5.65%, respectively.
Description. Male: Forewing costal margin length of holotype 15 mm, wingspan 33 mm; mean forewing length of paratypes 16 mm, wingspan 35 mm; head, thorax, abdomen and tegulae grey; antennae bipectinate, ½ the length of forewing; ground colour of forewing black, with white silvery pattern. Three white silvery patches form the pattern: fascia of even width runs along the entire costal margin, median fascia widening medially reaches the outer margin of forewing; lower silver patch originates at basal edge and extends along dorsal wing margin to middle. This patch enclosed by ground colour; adterminal line white; fringe grey. Dorsal surface of forewing greyishwhite; costal, outer and dorsal margins greyish-black. Hindwing uniform, white, with greyish black spot at costal margin. Female (Fig. 2): Forewing length of allotype 23 mm, wingspan 48 mm; antennae filiform; wing pattern as in males. Intraspecific variation. Adterminal line in some specimens missing; contours of silvery spots forming the pattern vary; hindwings grey.
Male genitalia (Fig. 21). Uncus broad, slightly narrower than its length; apex wide, slightly rounded; arms of gnathos long and strong; gnathos very broad, with rounded apex; apex of saccus gradually tapering, with a pointed denticle; valvae symmetrical, with straight margins, gradually widening apically; costal margin with strong and wide sclerotisation; apex flat; arms of transtilla medium sized, strong, denticleshaped; juxta large, strongly sclerotised, belt-shaped with a small indentation apically and a conspicuous boat-shaped margin at the basal area; aedeagus strong, straight, large, widening at the proximal end; vesica simple, wide, without cornuti.
Bionomics and distribution. Both males and females of the new species were strongly attracted to light and were distributed in almost all habitats of Socotra Island as well as the smaller islands of the archipelago -Samha and Abd al Kuri. Acacia is a likely food plant for M. brandstetteri as larvae of the closely allied species Mormogystia proleuca feed on Acacia [Hampson, 1896]. Also, the new species is especially abundant in the central part of the island, in deeper canyons or rich oasis-like valleys where for-ests haven't been cut for fuel like elsewhere on the island. Diksam canyon (Fig. 30)

Diagnosis.
Meharia is distinguished from all other Cossidae genus by a number of apomorphous characters: the specific "tineoid appearance", the reduction of the lateral processes of the juxta, the specific dorsolateral sclerotization of the asymmetric aedeagus and the specific ribbon -like epiphysis. Description. These are small to medium sized moths, females larger; eyes naked; male and female antennae bipectinate along their length; proboscis reduced; legs long, slender; foretibia bearing a ribbon-like epiphysis; forewing elongate, rounded on the outer margin; forewing pattern has alternate dark and pale spots and bands transversely; hindwing uniform. Male genitalia. Simple; uncus unpaired, short, beak-shaped; tegumen massive; arms of gnathos short, slightly broadened distally, fused to form small gnathos; valvae short, broad, with no harpe and processes costally; juxta without lateral processes, simple; saccus protruding backwards, small; aedeagus rather long, slightly curved and asymmetical due to dorsoapical sclerotisation.
Female genitalia. Ovipositor lobes short, slightly acute apically, covered with relatively short, thick bristles, in the shape of triangular sclerites, with long and rather wide apophyses posteriores on the lower part, strongly widening oar-like in the cranial fourth and bearing a slender membranous-like border; tergite and sternite of the 8th segment fused to form a complete circle; sternite slightly swollen, membranous caudally; tergite strongly elongate, bearing a pair of apophyses anteriores, widening oar-like cranially, approximately as long as ½ the length of apophyses posteriores; opening of ostium strongly protruding cranially, located on membrane between the 7th and 8th segments; ostium membranous, with poorly sclerotized lateral bands; antrum membranous, tube-shaped, 1½ times longer than the 8th tergite, narrowing sharply, separate form membranous ductus bursae; corpus bursae membranous, saccular, without signa.
Remarks. Eleven species of Meharia have been reported so far (Yakovlev and Saldaitis 2008), primarily from the deserts and arid mountains of the Western Palearctic and Africa. Diagnosis. The new species differs from the related species Meharia acuta Wiltshire, 1982 (Figs 8, 12) by forewing pattern, DNA and distribution. In M. acuta, the basal spot at the costal wing margin is missing. Meharia hackeri has a straight basal fascia at the costal wing margin for ¼ the length of forewing and a narrow white fascia, with a wide interruption antemedially and a narrow interruption tornally, running along the entire inner margin. M. acuta has no such fascia, but has a wide subterminal band. DNA barcodes clearly separate M. hackeri from M. acuta. Three identical sequences of M. hackeri were compared to those of a single M. acuta specimen resulting in a significant 7.48% variation.

Meharia hackeri
M. acuta is distributed in the Arabic peninsula, M. hackeri is endemic to Socotra Island.
Description. Female: Forewing costal margin length of holotype 10 mm, wingspan 21 mm; forewing length of paratypes 11 mm, wingspan 22 mm; antennae slightly longer than half the length of forewing; bipectinate, color white, black at base; head and tegular yellowish-white; labial palpi yellowish brown, white at base; ground colour of forewings yellowish-brown with white longitudinal fascia forming wing pattern, basal fascia in the costal area straight, running to ¼ the length of forewing, curved fascia extending medially from inner margin to ⅔ the length of forewing, its extension ends at terminal wing margin, medially the fascia and its interrupted portion in terminal area bordered by dark brown scales with black inserts; narrow white fascia, widely in-terrupted antemedially and narrowly interrupted tornally, runs along the entire inner margin, cilia yellowish-white, ventral forewing brown; hindwing greyish-yellow, cilia light brown, ventral hindwing brown.
Bionomics and distribution. Known only from the central part of Socotra Island. M. hackeri is likely endemic to Socotra Island. All specimens were collected in mid-January; M. hackeri females were attracted to light and appear to have a very local distribution as the species was discovered only in Difarroha Valley (Fig. 31). The new species was collected in the central part of the country in an oasis-type valley dominated by various tree and shrub species such as: Jatropha unicostata, Lycium socotranum, Gnidia socotrana, Buxus hildebrandtii, Croton socotranus, Punica protopunica, Ficus vasta, Euphorbia socotrana, Jathropha unicostata, Mitolepis intricata, Aloe perryi, Adenium obesum (Miller and Cope 1996). It flies with several other Socotra Archipelago endemic moths such as Meharia yakovlevi Saldaitis & Ivinskis, 2010, (Cossidae), Pelosia sokotrensis (Hampson, 1900) (Fig. 11): The authors examined the genital structures of several more male specimens, noting that the valvae are variable in shape being slightly narrower and slightly concave in costal and dorsal areas. The vesica is narrow, long, and almost the same length as aedeagus.

Diagnosis.
Aethalopteryx is distinguished from close Trismelasmos Schoorl, 1990, Acosma Yakovlev, 2011, Strigocossus Houlbert, 1916and Azygophleps Hampson, 1892 genus by having cup-shaped antennae in both sexes, forewings with slight reticulated patterns and reduced arms in males gnathos and particularly genital structure of the females. Description. Medium sized moths. Male and female antennae cup-shaped; forewing elongate with slight reticular pattern, often with a spot in the costal area and spots in the postdiscal area; hindwing with indistinct reticular pattern.
Male genitalia. Uncus long, thin, basally considerably narrower than width of tegumen; arms of gnathos reduced; tegumen massive; valvae with slightly uneven margins and with rounded apex; saccus massive, semicircular; juxta broad, with wide leafshaped lateral processes; aedeagus slightly bent, vesica with a long belt-shaped sclerite forming the projection of lateral aedeagus wall.
Female genitalia. Form short oviductus; papilla analis elongate, gradually narrowing; apophyses posteriores twice the length of apophyses anteriores which are furcate at basal part; ductus membranous, broad, very short; corpus bursae shaped like a long narrow sac, with a star-shaped signum on the lateral surface; bulla located in basal third of bursa on a long membranous ductus.
Remarks. Thirty-four species of Aethalopteryx have been reported , primarily from the east Africa with some distributed elsewhere in Africa or in the Arabian peninsula. Description. Male genitalia (Fig. 26). The authors examined several more male specimens and found some variation in the genital structures. Valvae of newly examined specimens were significantly wider; apex rounded; costal margin even; vertical juxta processes not tapering, with obtuse apices; vesica simple, long, tapering, almost the same length as aedeagus. Distribution. A newly described species, highly local, known only from the central part of Socotra Island from two valleys: the Diksam canyon (Fig. 30) and the Difarroha valley (Fig. 31), which are characterized by the following relict woody vegetation: Dracaena cinnabari, Buxus hildebrandtii, Croton socotranus and numerous other endemic plants (Miller and Cope 1996). Diagnosis. Azygophleps is distinguished from similar genera such as Sansara Yakovlev, 2004, Strigocossus Houlbert, 1916and Aethalopteryx Schoorl, 1990 by its females' apically bipectinate antennae, its long forewings rounded at the apex, the abscence of arms in its males' gnathos, its thick aedeagus, and a short, wide ductus and corpus with a small star-like signum in its females. Description. Medium sized moths. Male antennae cup-shaped, those of female bipectinate (apically with gradually reducing pectin); forewing long, with rounded apex, with dense reticular pattern formed by transverse lines and spots; hindwing lightly coloured and uniform.
Female genitalia. Forming long ovipositor; papilla analis stretched, slightly tapering towards apex; apophyses posteriores more than twice as long as apophyses anteriores which are forked basally; ductus short, wide, sclerotised at base; corpus sac-shaped, with a small star-like signum; bulla located on the apical part of bursa.
Female genitalia (Fig. 29). Papilla analis stretched, rounded apically; apophyses posteriores more than twice longer than apophyses anteriores which are forked at basal part; ductus short, wide, sclerotised basally; corpus sac-shaped, with a small star-like signum; bulla sclerotised, located on the median part of bursa.