African-Arabian and Asian-Pacific “ Mocisfrugalis ” : Two distinct species ( Lepidoptera : Noctuidae )

It is shown that under the name Mocis frugalis (F., 1775), considered to represent a widespread pest of graminaceous crops in the Eastern hemisphere and the Pacific, two species have been hitherto confused. Populations from Africa and Arabian Pen­ insula are described as Mocis proverai sp. n. The main characters which distinguish the African-Arabian M. proverai from M. fru­ galis of Asia and the Pacific are found in the genitalia, especially the configuration of the male vesica and female bursa copulatrix.

An intriguing phenomenon occurring in Mocis and other groups of the Catocalinae is the sharing of an extraordinarily similar habitus between species that con versely are well distinct genitalically.This often led early authors, who traditionally relied upon the external habitus for species identification, to treat different taxa as visually identical units (e.g.Warren, 1909Warren, -1914;;Hampson, 1913).Credit shouldbe givento Berio (1953Berio ( , 1954Berio ( , 1955Berio ( , 1956) ) for having recognised several species pairs in the Catocalinae, including Mocis undata (F., 1775) / M. mayeri (Boisduval, 1833) and M. repanda (F., 1794) / M. conveniens (Walker, 1858), respectively Asian / African and American/African, which were eventually diagnosed because of outstanding differences in the male genitalia.
As Wiltshire (1964) used 'Mocis frugalis F. subsp.nigripunctata Warren" while recording specimens from Bahrain which, during the course of this study, have revealed to belong to the new species, a question appar ently arises as to whether or not Wiltshire's (1964) cita tion made available the name nigripunctata, particularly when considering that Hacker (1999) listed "nigripunc tata Wiltshire, 1964" in the synonymy of M. frugalis in a catalogue of Arabian Lepidoptera.This circumstance is regulated by article 45.5.1.of the International Code of Zoological Nomenclature (International Commission on Zoological Nomenclature, 1999).According to this article, Wiltshire (1964) would have made available and taken authorship of nigripunctata only in case the name had fulfilled the requirements of articles 11-18, but it clearly contravenes those of article 13.1.The name nigripunctata with authorship assigned to E.P. Wiltshire thence does not enter into zoological nomenclature.Going through Wiltshire's (1964) paper it is evident that use of the term "subspecies" had been followed as a rou tine and without the intent to differentiate any population of Mocis.On the contrary, Wiltshire's (1990) statement that "in habitus (Mods frugalis) is variable but the various forms have no geographical significance" would not have been published without a prior synonymisation of nigripunctata.

MATERIAL AND METHODS
Male and female specimens corresponding to the old concept of Mocis frugalis from the Ivory Coast, Upper Volta, Ghana, Cameroon, Congo, Sudan, Kenya, Tanzania, Madagascar, Bah rain, Yemen, Ceylon, Afghanistan, China, Vietnam, Malaya, Borneo, Bali, and New Guinea, were dissected according to the standard procedures for genitalia preparations (e.g.Hardwick, 1950;Reid, 1983).As diagnostic features of major importance are often found in the vesica (= endophallus) (cf.Hardwick, 1950;Lafontaine, 1987;Mikkola, 1992) particular emphasis was given to the study of its configuration.Vesicae were everted by cutting the ductus ejaculatorius at its junction with the aedeagus with sharp microsurgical scissors; distilled water was then pumped into the aedeagus with a hypodermic syringe while immersed in distilled water, aedeagus and needle being held with a pair of fine forceps.Staining was carried out in a 1% mercurochrome solution for 15 h.Aedeagi were then soaked in ethanol (95%) to stop staining and harden the inflated vesicae.To allow comparisons between specimens drawings were made using a camera lucida attached to a Wild M5 stereoscopic microscope.In order not to alter the shape of vesicae, aedeagi were first grafted onto micropins pinned to cubes of cork and drawn while immersed in ethanol.Permanent slides were even tually prepared by mounting the genitalic parts in Euparal.A lettering was arbitrarily assigned to vesical swellings in order to unambiguously identify the lobes of the endophallus.variation, consisting of three main morphs and intermedi ates (cf.Strand, 1916;Gaede, 1935Gaede, -1937;;Berio, 1965) (Figs 1-6).At most, the background coloration of M. pro verai is often lighter, particularly in the distal half of the medial field of the forewing, thus producing a more con trasting pattern in the forms with dark markings.Both species are very variable in the genitalia structure, but some traits are constantly different and hold diagnostic value for M. proverai.In the male, the superior and infe rior processes of the left clasper are unequal, the superior being usually more than twice as long as the inferior, hence conferring a pronounced asymmetry to the whole apparatus (in M. frugalis the processes are of comparable length and the valvae approximately symmetrical) (Fig. 8).The left ampulla is longer and the stout superior process of periphallus is more sinuous, with the outer border (the smooth one) showing two points of inflection (i.e., "S"-shaped) and a distinct small (rarely two-three) preapical spine on the second flex, while in M. frugalis the border is more evenly curved and the spine is missing (Fig. 9).The inflated vesica of M. proverai is less mark edly bent toward aedeagal tube than in M. frugalis, lobe a being approximately twice as broad and lobe b bearing usually a finely spinulose field at apex, always absent in M. frugalis (Fig. 10).In M. proverai a large bag-like swelling c, absent in M. frugalis, protrudes dorso-laterally from the main body of the vesica and is linked to a sac cular heterolateral lobe d; this configuration determines a mesial constriction which does not occur in M. frugalis.In the latter species, lobe d is very long, distally tapering, and projecting downward; moreover, it is inserted in a so lowered position that it might be even questioned whether it is homologous with that in M. proverai.Lobes e and f of M. proverai are well distinct and laterally positioned, while in M. frugalis they form a largely united ventrally positioned body.Proximad to e and f there is a sclerite, broad and weakly sclerotized in M. proverai, small and intensely pigmented in M. frugalis.Last but not least, the distal lobes g, which are more slender in M. frugalis, bear totally different vestiture of spines; in M. proverai this consists of dense minute spiculae, whereas in M. frugalis the vestiture has more sparse long spines (differences in spinosity can be easily observed through the aedeagal wall without everting the vesica).The extent to which the shape of the superior process of the right clasper can vary is much greater in M. proverai.
In the female genitalia, the appendix bursae of M. proverai is weakly sclerotized and poorly defined, consisting of some posterolateral ribs lying on the flank of corpus like a pouch, but practically becoming part of the corpus when this is fully extended; in contrast, the appendix bursae of M. frugalis is deeply sclerotized and well sepa rate from the corpus, arising perpendicularly from it (Fig. 11).

Description
Male.Length of forewing 18-21 mm.Upperside facies as illustrated (Figs 1-3).Antenna filiform, light yellowish brown; head, thorax, legs and abdomen beige.Forewing light beige, with sparse brown scales, particularly along costa and above vein 1A+2A; elements of pattern dark brown; postmedial defined internally by pale yellowish beige.Variability occurs as to degree of straightness of postmedial, more or less pronounced, dimension of sub basal dot, which may also be absent, and intensity of dark pigmentation of background and any of all pattern ele ments, most conspicuous phenotypes showing net trans verse mesial patch above 1A+2A.Hindwing light beige with sparse brown scales, basally suffused by brown; postmedial and subterminal fascia greyish brown; tornal area beyond subterminal generally light.Underside beige with ochreous hue and diffuse grey markings consisting of patch at end of cell, postmedial, and wide postdiscal fascia at forewing, postmedial and subterminal fascia at hindwing, where small grey discal dot may also occur.
Further studies are however required for defining the actual ranges of the two species and to ascertain whether or not they overlap in some areas of the Middle East and the Indian Ocean islands, although there seems to exist a geographic disjunction between the two species from Saudi Arabia to Afghanistan.
In addition to the external similarity between the two species, the fact that they also share the same basic colour polymorphism undoubtedly represents an unusual circum stance.This phenomenon is commonly observed in vicariant species pairs, at least within the Noctuidae, and may be put in relation to speciation events subsequent to the acquisition of the genetic variation by the common ancestor.Point of major interest would be the elucidation of the reasons for a much greater variability of male genital structures in the African-Arabian taxon.Some traits are presumably subject to geographical variation, e.g. the superior process of the left clasper is seemingly shorter in East African material, the preapical spine on the outer border of periphallus is much reduced in speci mens from Bahrain, and almost any structure of a specimen from Sudan appears as more slender, but it is an intrapopulational variability of features like the right clasper that has no correspondence in M. frugalis.Whether this situation reflects different levels of genetic variation in the two species or a greater developmental stability in M.frugalis is a matter of speculation.