Mesophleps Hübner, [1825]

Li, Houhun & Sattler, Klaus, 2012, A taxonomic revision of the genus Mesophleps Hübner, 1825 (Lepidoptera: Gelechiidae) 3373, Zootaxa 3373, pp. 1-82 : 7-15

Mesophleps Hübner, [1825]

Mesophleps Hübner, [1825] , Verz. bekannter Schmett.: 406. Type-species: Tinea silacella Hübner, 1796 , Samml. eur. Schmett. 8: 37, pl. 17, fig. 117, by subsequent designation: Meyrick, 1925: 168.

Brachyacma Meyrick, 1886 , Trans. ent. Soc. Lond. 1886: 278. Type-species: Brachyacma epiochra Meyrick, 1886 , ibidem 1886: 279, by monotypy. [Synonymized by Park, 1990: 136; Li & Zheng, 1995: 27, 33.]

Lathontogenus Walsingham, 1897 , Proc. zool. Soc. Lond. 1897: 87. Type-species: Lathontogenus adustipennis Walsingham, 1897 , ibidem 1897: 88, by original designation and monotypy. [Synonymized with Brachyacma Meyrick by Meyrick, 1925: 168, and Mesophleps Hübner by Li & Zheng, 1995: 27, 33.]

Paraspistes Meyrick, 1905 , J. Bombay nat. Hist. Soc. 16: 600. Type-species: Paraspistes ioloncha Meyrick, 1905 , ibidem 16: 600, by monotypy. [Synonymized with Lathontogenus Walsingham by Walsingham, 1915: 408, Brachyacma Meyrick by Meyrick, 1925: 168, and Mesophleps Hübner by Li & Zheng, 1995: 27, 33.]

Chretienia Spuler, 1910 , Schmett. Eur. 2: 359. Type-species: Gelechia oxycedrella Millière, 1871 , Iconogr. Descr. Chenilles Lépid. inédits 3: 177, 193, pl. 118, figs 1–6, by monotypy. [Synonymized by Park, 1990: 136.]

Lipatia Busck, 1910 , Bull. Dep. Agric. Trin. 9: 243, Type-species: Lipatia crotalariella Busck, 1910 , ibidem 9: 244, fig., by original designation and monotypy. [Synonymized with Lathontogenus Walsingham by Walsingham, 1915: 408; Brachyacma Meyrick by Meyrick, 1925: 168; Mesophleps Hübner by Li & Zheng, 1995: 27, 33.]

Stiphrostola Meyrick, 1923 , Exot. Microlepid. 3: 25. Type-species: Stiphrostola longinqua Meyrick, 1923 , ibidem 3: 25, by monotypy. [Synonymized by Park, 1990: 136, as Stiprotola, an incorrect subsequent spelling.]

Crossobela Meyrick, 1923 , Exot. Microlepid. 3: 34. Type-species: Crossobela barysphena Meyrick, 1923 , ibidem 3: 34, by original designation and monotypy. [Synonymized by Park, 1990: 136.]

Xerometra Meyrick, 1925 , Genera Insect. 184: 18 [key], 170. Type-species: Nothris crocina Meyrick, 1904 , Proc. Linn. Soc. N.S.W. 29: 421 [key], 423, by original designation. [Synonymized by Park, 1990: 136.]

Gnosimacha Meyrick, 1927 , Exot. Microlepid. 3: 354. Type-species: Gnosimacha catericta Meyrick, 1927 , ibidem 3: 354, by monotypy. [Synonymized by Park, 1990: 136.]

Bucolarcha Meyrick, 1929 , Exot. Microlepid. 3: 515. Type-species: Bucolarcha geodes Meyrick, 1929 , ibidem 3: 515, by monotypy. Syn. nov.

Uncustriodonta Agenjo, 1952 , Faunula lepid . almeriense: 87. Type-species: Mesophleps trinotella Herrich-Schäffer, 1856 , Neue Schmett. Eur. angrenzenden Ländern (1): 6, fig. 46, by original designation and monotypy. [Synonymized by Park, 1990: 136, as Uncostridonta , an incorrect subsequent spelling.]

Uncostridonta Park, 1990 , Korean J. appl . Ent. 29: 136, an incorrect subsequent spelling.

Head. Frons evenly convex; ocellus absent; proboscis short, basal half squamose. Antenna two-thirds to four-fifths length of forewing, scape without pecten (except in M. catericta ), apical segment often black. Labial palpus variable, recurved, typically segment 2 with dorsal scales raised or fanned out towards apex, 3 shorter than 2, unremarkable; sometimes 2 with sub-triangular forward-directed brush ( catericta, tephrastis -group); exceptionally palpus porrect, segment 2 with triangular dorsal brush, 3 very short (geodes).

Wingspan 6.5–26.0 mm. Forewing yellow to yellowish brown, rarely dark brown, grey-brown or grey, frequently with dark costa, particularly in distal half, sometimes with small plical, discal and discocellular spots ( Fig. 1). Exceptionally wing distinctly marked with large plical spot, discal obliquely extended to middle of costa, and pair of spots on distal fifth of costa and in tornus often fused to form transverse band ( oxycedrella ). Forewing narrow to broadly elongate-ovate, venation variable. Forewing costa with or without pterostigma between Sc and R 1; R 3 free or stalked with R 4+5, common stalk of R 4+5 about as long as free R 4 and R 5, rarely much longer, M 1 approximated to, connate or stalked with R 4+5, CuA 1 separate, approximated to or connate with M 3. Shape of hind wing variable; costa weakly sinuate, costal and dorsal margins diverging, wing distally up to twice its width at base, termen moderately concave beneath apex; or costal and dorsal margins almost parallel, costa gently arched, termen strongly concave beneath sharply produced apex. R 1 absent or joining Sc near base; Rs +M 1 stalked, M 3 arising near CuA 1 or both veins connate ( Figs 2–6; Weber 1948: 225, pl. 12, figs 5–7). Frenulum of female composed of three acanthae (in M. catericta sometimes only two).

Pregenital abdomen. Scales on tergites TI-III of both sexes yellow, rarely yellow colour restricted to TI and II, or all segments unicolourous; scale sockets on denuded TI, TII and sometimes TIII, denser and bigger than on other segments ( Fig. 11). Anterior margins of TIV–VII (IV–VIII in males of M. geodes and catericta ) in both sexes with variable, narrow to broad, transverse band of densely set posteriorly-directed microtrichia ( Figs 17–22); SII with pair of venulae and pair of short apodemes, sensory setae small, fairly scattered ( Fig. 11). Segment VII in female, VIII in male a closed ring, rarely modified (males of corsicella , bifidella , gigantella and geodes ) ( Figs 14–16).

Genitalia ♂ ( Figs 7, 8). Uncus variable, pointed, round, oval or sub-rectangular, rarely bilobed ( bifidella , Fig. 71) or otherwise modified, strongly sclerotized in many species. Gnathos composed of evenly curved transverse band bearing pair of always very strongly sclerotized posterior hooks; rarely gnathos hooks fused at base or merged to one ( tephrastis -group). Tegumen unremarkable, usually as wide as or slightly wider than uncus, with anterior margin shallowly concave to triangularly excised; pedunculi variable, simple and long, evenly curved, to distally broadened, forked. Diaphragma with groups of sensory setae. Valva narrow, simple, undivided, barely shorter than tegumen; small group of long sensory setae situated at base, near junction with vinculum and pedunculus. Sacculus and juxta merged with vinculum. Arms of vinculum narrow, distally broad, distal margin strongly sclerotized and turned ventrad, beneath exit hole of phallus often notched or excavated. Phallus usually shorter than vinculum, in albilinella -group distinctly longer, basal half to two-thirds bulbous, apical half to one-third narrow; with short spur that articulates with juxta part of vinculum frame; ductus ejaculatorius enters anteriorly; bulbus ejaculatorius slightly longer and wider than phallus.

Genitalia ♀ ( Figs 9, 10). Papillae anales usually of typical gelechiid shape, weakly to moderately sclerotized, strongly setose; in geodes -group very broad; in tephrastis -group long, narrow, sparsely setose; apophyses posteriores usually short, two to three times length of papillae anales. Segment VIII simple, evenly sclerotized, posterior margin dorsally convex to medially prominent, without sensory setae (except in M. catericta ). Apophyses anteriores thin, rod-like, about one-half length of apophyses posteriores; rarely both pairs of apophyses long, up to about three times length of segment VIII (long in M. silacella and tephrastis -group). Position of ostium bursae variable, often near anterior margin of VIII; sclerotized antrum, if present, variable, short to very short, funnel-shaped. Ductus bursae thin, straight, at most twice length of apophyses anteriores (up to ten times length of apophyses anteriores in M. epiochra ), entering corpus bursae posteriorly or laterally; corpus bursae oval to pyriform, delicately membranous, sometimes finely reticulated, with or without cervix bursae, usually without signum but in M. gigantella sp. nov. and tephrastis -group with sclerotization between ductus bursae and ductus seminalis ( Fig. 13). Origin of ductus seminalis from bursa copulatrix variable, from corpus or cervix bursae or, exceptionally, from ductus bursae near corpus ( geodes , Fig. 110).

Remarks. Amongst the genera synonymized with Mesophleps by Park (1990: 136) (with reference to KS but without his authorization) he listed ‘ Paltodora Lower’. Paltodora sensu Lower is a misidentification of Paltodora Meyrick, 1894 , a junior subjective synonym of Monochroa Heinemann, 1870 (Anomologinae) .

As far as we were able to ascertain, all Mesophleps species lack the ocelli. Meyrick (1925: 1) assumed that ocelli are always present in Gelechiidae and routinely stated ‘ocelli posterior’ even in many instances in which they are clearly absent. It is puzzling that Müller-Rutz (1922: 243) emphasized the presence of distinct ocelli in M. trinotella . None of the trinotella examined by us showed any trace of ocelli and Müller-Rutz probably erred. However, in the family Gelechiidae the external ocelli are frequently reduced and have been lost independently more than once. It would therefore not altogether surprise to discover a species in which specimens with and without ocelli existed.

The vestiture of segment 2 of the labial palpus is variable; the segment is either ventrally smooth-scaled, but with rough, dorso-distally raised or fanned out scales, or it is dorsally more or less smooth-scaled but bears a distinct ventral brush. As the dorsal scales can be raised and spread to a greater or lesser extent, segment 2 may appear distally thicker or thinner within a species. The colour of segment 2 is usually black in fresh specimens, lighter on the mesial surface, except for a light distal ring. In older specimens the black colour fades to a dark brown. Segment 3 varies in length but is rarely less than two-thirds the length of 2; it is usually white, sometimes with a few black scales at the base and a broader or narrower black sub-apical ring. Exceptionally ( albilinella ) segment 2 and the basal half of 3 are entirely black.

The function of the microtrichial bands on abdominal tergites IV–VII (or VIII in male) is as yet unknown. Isolated very small microtrichia can sometimes be observed in the intersegmental regions but tergal bands of distinct microtrichia are rare. They are known elsewhere in the Gelechiidae in unrelated genera, for example in all species of the Neotropical genus Charistica Meyrick, 1925 (Anacampsini) , South African Ischnophylla similicolor Janse, 1963 , Palaearctic Metanarsia alphitodes (Meyrick, 1891) (TIV–VII, both sexes) and Proactica halimilignella Walsingham, 1904 (Apatetrini) , in the last species on tergites III–VIII in the male and III–VII in the female. In the large Australian genus Ardozyga Lower, 1902 (subfamily still to be established) they are absent in most species but do occur at least in A. penthicodes (Meyrick, 1921) . In Mesophleps the extent of the bands varies considerably between species. It is narrow in silacella and corsicella and on TVII is reduced to small patches in the middle of the dorsum. In contrast, in M. geodes and catericta it is broad, extremely well developed and, in the male, also found on TVIII ( Figs 19, 21). Outside the Gelechiidae such microtrichial bands occur, for example, in Proceleustis zelotypa Meyrick, 1918 (TIII–VIII, male; female not examined) ( Cosmopterigidae ). Such microtrichia should not be confused with abdominal spines (macrotrichia) that are common in Xyloryctidae , Coleophoridae , Batrachedridae , Lecithoceridae and others. Microtrichia are fixed outgrowths of the cuticle whilst macrotrichia (hairs, scales, sensory setae etc.) are deciduous, and can be identified by their basal sockets.

The ovipositor of Mesophleps is typically of the standard gelechiid type: laterally compressed, moderately sclerotized, broadly sub-triangular papillae anales set with sensory setae of various sizes. The latter are short but particularly dense around the apex and very long and strong in a single line along the anterior (proximal) margin of the papillae. In the tephrastis -group the ovipositor is specialized. The papillae anales are unusually long and narrow ( Figs 10, 12), more strongly sclerotized, and their cover of sensory setae is somewhat reduced. In particular there are no long and strong sensilla on the anterior margin of the papillae. These specializations in conjunction with the extra long and strong apophyses anteriores and posteriores suggest a mode of oviposition different from that of other members of this genus, probably involving the insertion of the ova into a substrate rather than depositing them onto a surface. However, no host-plant is known for any member of the tephrastis -group and no suggestion can be made as to the possible substrate.

In the female genitalia of many Gelechiidae the tergite and sternite of segment VIII are firmly fused to a sclerotized ring without a clear division to separate the two sclerites, and it is impossible to determine how far the tergite extends ventrad or the sternite dorsad. Reference points that would define the pleura, such as the spiracle in segment VIII, are usually but not always absent in Gelechiidae .

The ostium bursae is small and opens under an often more or less trapezoid subostial plate. There exists a very short funnel-shaped or tubular sclerotized antrum ( Figs 9, 10) that rarely exceeds the transverse anterior edge of the subostial plate. The ductus bursae is always thin and usually of moderate length, about twice the length of the apophyses anteriores; exceptionally it can reach almost ten times that length ( M. epiochra ). In virgin females the wall of the corpus bursae is delicately crinkled and appears finely reticulated; after insertion of a spermatophore the corpus is larger and its wall is smoothed out. M. gigantella , the largest species in the genus, is the only one outside the tephrastis -group, to have a signum in the shape of a small spiny patch that separates the ductus bursae from the ductus seminalis.

Biology. Although there are many host-plant records, the early stages of Mesophleps are poorly known except those of M. oxycedrella , the biology of which was described in some detail by Millière (1871: 177) (see below). The ovum is still undescribed but was once illustrated for M. trinotella ( Gregor & Povolný 1955: pl. 7, fig. 1). It is probably of the ‘flat’ type, i.e. its micropylar axis runs more or less parallel to the substrate. It is an elongate oval with blunt ends and its surface is reticulated with stronger longitudinal ribs. There are almost no records of the larva; that of adustipennis was unsurprisingly described as ‘whitish’ ( Leonard & Mills 1931: 472, as palpigera ), that of oxycedrella was illustrated and described in greater detail by Millière (1871: 177, pl. 118, figs 1–6), that of silacella briefly by Meess (1910: 371) and some aspects of the chaetotaxy of trinotella were discussed and illustrated by Gregor & Povolný (1955: 126, pls 1–3) who also figured the pupa (1955: pl. 7). The ovum is deposited singly on the flower, berry or seed pod of the host-plant. The larva lives in the seed pods or fruits of various Cupressaceae , Cistaceae, Cruciferae, Leguminosae and Rubiaceae where it feeds on the seeds. Dipterocarpaceae , sometimes reported for ‘ palpigera ’ ( Browne 1968: 114; Intachat 1998; Robinson et al. 2001: 263) are as yet unconfirmed; it seems that all records go back to Mathur et al. (1958: 81, 93). Pupation takes place within the pod, and the adult emerges after about ten days.

Economic importance. Some species have gained local economic importance, for example M. adustipennis (usually recorded as Brachyacma palpigera ) as a pest of pigeon pea ( Cajanus cajan ) in the West Indies, whilst an as yet unidentified Mesophleps species was studied for its impact as a seed predator on Parkinsonia aculeata , an introduced weed in northern Australia ( Van Klinken 2005: 414). Mesophleps sublutiana Park can cause significant damage to the seeds of Robinia pseudoacacia , an important roadside tree in parts of China. In some North American websites such as Bug Guide (http://bugguide.net/node/view/92721/bgref) and Checklist of the Lepidoptera of Florida (http://www.fsca-dpi.org/ Lepidoptera /LepidopteraFLChecklistText.htm), Brachyacma palpigera is listed as the Soybean Webworm. This term is misleading as Mesophleps (= Brachyacma ) larvae are exclusively seed feeders, mostly in the seed pods of leguminous plants including soybean. Confusion is possible with the Alfalfa Webworm Moth, Loxostege cereralis (Zeller) (Crambidae) , the larvae of which predominantly damage the leaves of alfalfa but occasionally also cause problems on soybean leaves.

Distribution. Present on all continents except Antarctica. Widely distributed throughout the temperate and tropical parts of the Old World ( Figs 23, 24). It is still uncertain whether the only American species ( M. adustipennis ) is a New World endemic or an inadvertent introduction from the Old World (Africa). It is known from the USA (Florida, Texas, California), Central America ( Honduras, Panama, West Indies) and some of the more northerly parts of South America ( Venezuela, Brazil, Peru, Galapagos Islands) ( Fig. 25).