Geometrini

This tribal concept embraces all of the Geometrinae except the Dysphaniini. Therefore any groupings recognised within it will have subtribal status (names ending in -iti: the alternative suffix -ina is used at a higher level in the Lepidoptera, e.g. Heterobathmiina, Neopseustina; see also Nässig (1995) for use of -iti). Before assessing the validity of such groupings proposed in recent literature (e.g. by Inoue (1961) andFerguson (1969)) and the relationship between New World and Oriental concepts (see also Pitkin (in press)), the characters that may serve to define the tribe as a whole will be discussed. Most of these are widely distributed over the group but are not necessarily well developed in all taxa. Nevertheless, they might be considered to be geometrine ground-plan features.

There are perhaps seven such characters. In addition, the cruciform vinculum feature mentioned above as a possible synapomorphy for Dysphaniini and Geometrini sees its greatest development in some genera of Geometrini, e.g. in Figs 123, 151, 172, 202, 233, 279, 284, 344, 361 and 378.

Green colouration. This feature is widespread throughout the group except in the more robust Pseudoterpniti genera, though even these include a number of taxa where green is extensive, e.g. Herochroma Prout and Actenochroma Warren.

Reduction of the frenulum. This character was noted by Prout (1912a) and Ferguson (1985) as a feature partially diagnostic for Geometrinae: the frenulum is reduced in size or absent. This is associated with expansion of the humeral area of the hindwing that becomes more angled at the position of the frenulum base (e.g. Fig 3). This character is variable throughout the group, relatively weakly developed in most Pseudoterpniti but strongly so in the Hemitheiti.

Paired setal patches on male sternite 3. Setal patches on sternite 3 are present generally throughout the Geometrini though they are absent from a scattering of genera (e.g. Ornithospila Warren). In most cases they are small, widely separated (Figs 241-243), and not elongate as in the Desmobathrini. In a few genera (e.g. Jodis Hübner, Berta Walker) they are more generally dispersed sparsely over a central circular area (Figs 384, 399), but modification of this type occurs sporadically and rarely in a number of generic groupings and probably represents a derived state of the ground-plan pair of setal patches. It is not clear whether this character is homologous or homoplasious with the condition in the Desmobathrini. Setae on this segment are usually associated with the presence of a hair pencil sheathed in the hind tibia (Holloway, 1993 [4]: 11), and this may prove to be a synapomorphy grouping together the Desmobathrinae, Geometrinae and Ennominae (where the setae occur in a transverse comb).

Socii of male genitalia well developed often with parallel reduction of uncus. Setose socii arising from the junction between the base of the uncus and the bases of each side of the gnathus, are moderate to strong in all Geometrini, but vestigial in the Dysphaniini. However, the development varies from the level seen in some Ennominae tribes and the Eumeleini, e.g. in the Nemoriiti and Rhomboristiti, where the uncus is relatively strong, through the condition in the Hemitheiti where they usually equal the uncus in length and are closely adpressed to it, to that in the Pseudoterpniti, Geometriti and Comibaeniti where the uncus is vestigial and the socii predominant.

Aedeagus with sclerotisation reduced to a ventral strip along length. The aedeagus is usually differentially sclerotised more strongly ventrally, a feature also seen moderately in the Dysphaniini, but only weakly developed, if at all, in a few Geometrini groups, such as the Pseudopterpniti (Epipristis Meyrick is an exception). Prout (1912a) described this condition as pestillate (pestle-shaped). The aedeagus vesica usually lacks significant cornuti, exceptions being Pingasa Moore and Metallolophia Warren in the Pseudoterpniti, Spaniocentra Prout in the Rhomboristiti, Chlorissa Stephens in the Hemitheiti, and the genera Dooabia Warren and Paramaxates Warren.

In the majority of genera showing this feature of ventral sclerotisation the insertion of the ductus ejaculatorius tends to be more placed to one third to half way towards the apex of the aedeagus.

Oblique, papillate ovipositor lobes. The distal margin of the ovipositor lobes recedes obliquely ventrally, with the setae set irregularly on papillate projections (see Figs 157, 225, 291, 323 and 386). This appears to be one of the most clearly definitive features of the Geometrini and is widely distributed over the included genera. It is absent in only a few instances, notably in the Geometriti, but also in the possibly allied Timandromorphiti and the genus Paramaxates: in these groups the lobes are somewhat semicircular and normally setose. In the Neohipparchiti the ovipositor lobes are sclerotised, acute.

Bicornute signum. When a signum occurs in the bursa copulatrix, it generally consists of two small spines on a sclerotised pad (e.g. Figs 162, 215, 274 and 314). This is modified in some taxa into a more irregular, transverse ridge or less well defined sclerotisation, e.g. in some Nemoriiti (Pitkin, 1993). The bicornute state is also present in Pseudoterpniti, Geometriti, and the majority of Hemitheiti, though is modified to a disc or ring in Aporandria Warren and Oenospila Swinhoe. The principal exception noted in the Bornean fauna is OrnithospilaWarren where the signum is an ovate patch of scobination.

The two female characters, together with green colouration, appear to provide the best definitive features for the tribe.

Salkeld (1983) noted that the eggs of geometrines were mostly of a flattened, pill-box shaped type, but that this shape was not unique to the subfamily. The larvae often have a strongly granular skin, not seen in Dysphaniini.

Features that may be useful to group genera into subtribes include the degree of development of the socii versus the uncus, pectination of the male antennae, facies characters, such as for the Pseudoterpniti, and characters of the venation of the hindwing. In the Hemitheiti veins M3 and CuA1 usually share a common stalk. In Nemoriiti this feature is sometimes present (Pitkin, 1993), more constantly so in Indo-Australian representatives (e.g. Fig 3). In other groups these veins are connate or separate.

There follows a preliminary attempt to define groupings of genera in the Oriental fauna and to relate these to New World groupings (e.g. in Ferguson (1969) and Pitkin (in press)). However, the classification is not sufficiently clear to merit formal subtribal headings in the account of the Bornean fauna following.

Some reference is also made to the findings of Stekolnikov & Kuznetsov (1981), studying male genital morphology of a small selection of Palaearctic genera.

Pseudoterpniti (= Archaeobalbiti, and Terpnini sensu Inoue (1961)). This name probably embraces all the relatively large, robust Indo-Australian genera where the facies consists of a more mottled forewing ground, with strong, crenulate fasciae: a rather boarmiine-like facies. On the underside there are strong black discal dots and broad black bands towards the margin in most taxa, though not the type genus, the Palaearctic Pseudoterpna Hübner. In the hindwing the frenulum is moderate and the humeral zone not particularly expanded. The male antennae are filiform, ciliate, serrate or (as in the type genus) rather narrowly and densely bipectinate, the pectinations tapering away to a point between two thirds and four fifths of the way to the apex. Veins M3 and CuA1 of the hindwing are usually separate.

In the male genitalia the aedeagus is usually tubular, not more strongly sclerotised ventrally. Coremata are usually present on the valves. Interpretation of the condition of uncus and socii is difficult. Either the socii have become fused to the basal plate of the uncus, with the distal part of the latter reduced or absent, the socii themselves becoming massive, even fused to give what appears to be a bifid uncus in genera such as Pingasa and DindicaMoore, or the socii are vestigial to absent, with the uncus becoming increasingly divided, the processes becoming well separated, often massive. In Actenochroma, a central digitate feature may represent the uncus and would lend support to the first alternative: usurpation of the function of the uncus by the socii, with convergence and fusion of the latter in some taxa. Herochroma, with a weak, bibbed uncus, represents an intermediate condition. A transformation series along these lines is represented by the following sequence of genera in the group occurring in Borneo: Orthorisma Prout (socii small relative to massively bilobed uncus), Actenochroma, Herochroma, Sundadoxa Gen. n., PullichromaGen. n., Metallolophia Warren, Epipristis, Pingasa, Pachyodes Guenée, Lophophelma Prout, Dindica. The tribal type genus has the socii/uncus structure much as in Epipristis.

In the female genitalia, both ovipositor lobes and signum (when present, e.g. in Herochroma) are typical of the Geometrini.

Geometriti. This, the nominate subtribe, consists also of robust taxa with a bifid uncal structure that is either homologous or homoplasious with the situation in the Pseudopterpniti. The two groups are distinguished by facies and the condition of the ovipositor lobes. The facies of Geometriti is a uniform, clear green, with paler rather than darker, fasciation on the upperside and no strong black marking on the underside. The ovipositor lobes are atypical, lacking the diagnostic Geometrini form described above, resembling more the typical geometrid condition. The signum is bicornute. The condition of the ovipositor lobes may represent a reversal.

The forewings are often falcate, particularly in the two Bornean genera of the group, Tanaorhinus Butler and Mixochlora Warren, but only (and much more weakly) in a few species of the typical genus Geometra Linnaeus.

The male antennae are narrowly bipectinate, and veins M3 and CuA1 are separate in the hindwing.

The larvae of the type genus are characterised by paired conical processes occurring dorsally, directed forwards, on segments A1-5 and A8.

Groups that may be related to Geometriti include the Timandromorphiti, Neohipparchiti and Aracimiti.

Timandromorphiti. This subtribe consists only of the type genus, Timandromorpha Inoue. This has a prominently bifalcate forewing and rather distinctive facies. Venation of the hindwing is as in Geometriti, and the male antennae are moderately bipectinate. In the male genitalia the socii and uncus are equally developed; the valves are invested with an irregular array of short, robust setae, and the aedeagus is slender, tubular. The eighth segment of the male abdomen is modified, sclerotised, a feature also seen in Aracimiti. The female genitalia have the ovipositor lobes intermediate between the characteristic geometrine type and the unmodified condition of the Geometriti.

Neohipparchiti. Neohipparchus Inoue has venation as in the Geometriti and somewhat similar facies. In the male genitalia the uncus has a slender, rodlike distal portion flanked by robust socii. In Chloroglyphica Warren, represented in Borneo, the socii can be separated by a rather broad, U-shaped basal portion of the uncus: in this the genus shows some resemblance to Actenochromaof the Pseudoterpniti. In both genera the male eighth sternite is variously modified and the aedeagus sometimes has a lateral spur. The male antennae are narrowly bipectinate.

The female genitalia have the ovipositor modified into an acute, slender, conical structure with a sparsely setose, smooth surface, possibly a modification of the Geometriti condition. The bursa copulatrix is large, narrowly elliptical, slightly fluted and more sclerotised and finely scobinate basally: there is no signum.

Aracimiti. The eastern Palaearctic genus Aracima Butler bears a loose external resemblance to a number of Bornean taxa such as Paramaxates Warren, Dooabia Warren, Euxena Warren and Chlorodontopera Warren. Aracimaitself has a remarkably expanded male eighth segment with broad, lateral, hook-like flaps, and the uncal structure consists primarily of the socii modified as robust, clawed plates. The ovipositor lobes of the female are of the modified geometrine form. Setal patches are present on the male third sternite, and the male antennae are narrowly, robustly bipectinate.

Dooabia has the uncus reduced to socii much as in Pseudoterpna, and the male eighth segment is slightly modified. The female hasmodified geometrine ovipositor lobes and a bicornute signum. In Paramaxates the eighth segment of the male is massively developed. The socii are strong, slender, curved, digitate, separated by a small plate representing the uncus. In the female the ovipositor lobes approach the Geometriti condition: there is a bicornate signum. The male antennae of both genera are filiform, lacking cilia.

Euxena and Chlorodontopera resemble each other in facies. In the males Chlorodontoperahas the eighth segment weakly modified, whereas in Euxena it is barely so. Uncus and socii are strong in both genera, the former slender in Euxena, broad in Chlorodontopera. The ovipositor lobes of both are of the modified geometrine form. The signum is a transverse flange in Euxena, but is absent in Chlorodontopera. The male antennae in Euxena are filiform, but in Chlorodontopera they are narrowly bipectinate.

These four genera are perhaps best placed in the vicinity of Geometriti and allied groups on the strength of the development of their socii relative to the uncus, rather robust character and general facies. The venation of the hindwing is also consistent with this placement, CuA1 and M3 arising separately from the cell in all except Euxena where they share a common stalk.

Agathia Guenée. This diverse Old World genus does not fit easily within any currently recognised tribal grouping, but it would be unwise to erect a new one until the classification of the Geometrini as a whole is better understood. The uncal structure resembles that of Pseudoterpna and Dooabia in apparently consisting of the two socii closely adpressed, fused over their basal half, with the uncus itself vestigial, reduced to a plate between the base of the socii. In the female the ovipositor lobes are of the modified geometrine type, with the signum typically bicornate. The valves of the male are distinctively ornamented. The setae on the third sternite are well developed. The facies is also striking and diagnostic, and the male antennae are filiform, lacking cilia. In the hindwing, veins CuA1 and M3 are connate at the cell. Stekolnikov & Kuznetsov (1981) suggested the genus could be placed in the Ochrognesiini (see Nemoriiti below).

Ornithospila Warren. This genus is set apart from the rest of the Geometrini by the condition of the female signum: elongate, ovate, scobinate. The ovipositor lobes are of the modified geometrine type however. The hindwing venation is as in the groups already discussed. The male antennae are bipectinate to three-quarters, the pectinations narrow, neat and numerous. The green of the wings is bright as in Agathia rather than more emerald as in most other groups.

The male abdomen lacks setal patches on sternite 3. The vinculum lacks the strongly cruciform state seen in many Geometrinae, and there is development of a slight saccus. The socii are slender, closely adpressed to the uncus as in the Hemitheiti, but unusually doubled (an additional smaller outer process) in the typical subgenus.

Nemoriiti. The New World tribe Nemoriini recognised by Ferguson (1969) and reviewed by Pitkin (1993, in press) is represented in the Indo-Australian tropics by the Ochrognesiini of Inoue (1961). The New World name has priority. The tribe can be defined principally on features of the male abdomen: a central longitudinal thickening and sclerotisation of the eighth sternite that bifurcates along the anterior margin that is usually concave or obtusely cleft, and broadens posteriorly around a cleft, often between a pair of lobes, or acute processes; a similar but shorter sclerotisation of the anterior margin and lobing of the posterior margin of the eighth tergite; an elongate, often apically spatulate or even bilobed uncus, set between moderate to well developed, often divergent socii; sclerotisation of the valve costa, often modified or produced into processes along its length from base to apex. The modification of the eighth sternite is the most consistently present of these features.

The saccus is sometimes bilobed, the vinculum tending towards the Comibaeniti condition. Coremata are present at the base of the valves.

The venation of the hindwing has the condition of veins M3 and CuA1 relative to the cell variable, ranging from separated to sharing a common stalk. The antennae of the male are usually bipectinate in Neotropical taxa (Pitkin, 1993) and more variable in Indo-Australian ones, with ciliate and serrate states evident as well as the pectinate one.

Rhomboristiti. The two Indo-Australian genera grouped under this name, Rhomborista Warren and Spaniocentra Prout, and a new one described on (Rhombocentra Gen.n.), share two particular features of the male genitalia: a strong uncus with only weak socii (perhaps a plesiomorphic feature or a reversal), but with a similarly strong gnathus; a prominent harpe-like process, often double, in the centre of the valve. There are no coremata on the valve. The facies has irregular marginal blotches of a type only otherwise seen in the Comibaeniti amongst the Indo-Australian fauna. The genitalic features are also seen in the New World Lophochoristiti, though the socii are moderate, and also the western Palaearctic Heliotheiti. The name Rhomboristiti has priority. The male antennae are bipectinate, and setal patches are present on the third sternite. M3 and CuA1 are separate or connate on the hindwing. The ovipositor lobes of the female are of the modified geometrine type, but no signum has been observed in the bursa of the taxa dissected.

Comibaeniti. This group is again defined on genitalic features. In facies many taxa resemble some Spaniocentra species. The most distinctive genitalic feature is the vinculum which has become a narrow sclerotisation that is broadly square or triangular with a shallowly concave zone between the angles. In the extreme situation of Comostolodes Warren, the two angles have converged to give an acutely bifid effect, and the sclerotisation of the eighth sternite shows parallels with the definitive state for Nemoriiti.

The socii are prominent, as much or more so than the uncus which is bifid in most cases, vestigial to absent in Comostolodes and Protuliocnemis Gen. n.. Valve ornamentation when present is costal, often a massive spur.

The male antennae are strongly bipectinate. Veins M3 and CuA1 in the hindwing are separate or connate. The ovipositor lobes are of the modified geometrine type, though this feature is not marked. The signum, when present, is bicornute or a ridge.

The larva has the habit of attaching debris to itself (McFarland, 1988; see also illustrations in Sugi (1987)). This feature is also observed in the New World Synchloriti (Ferguson, 1969; McFarland, 1988; Pitkin, in press), where similar characteristics of the uncus and socii occur, but a more typical cruciform condition is seen in the vinculum. The groups are probably related. The name Comibaeniti has priority.

Stekolnikov & Kuznetsov (1981) separated this group from the rest of the Geometrini on the basis of their study of male genital morphology, but characters of the male eighth sternite and of the flanged larva suggest a relationship to the Nemoriiti.

Bornean genera included are Comibaena Hübner, Argyrocosma Turner, Comostolodes and Protuliocnemis. The Palaearctic genus Thetidia boisduval also belongs to the group.

Hemitheiti. This subtribe embraces the majority of the Geometrini, particularly the more bluish or emerald green taxa. A number of possibly apomorphic features are found widely in the group, though not necessarily in every genus.

The socii and uncus are more or less equivalent in size, the former never less than half the length of the latter and usually closely adpressed with it. Veins M3 and CuA1 of the hindwing are usually stalked. The greatest reduction and frequency of loss of the frenulum also occur in this group. The male antennae are often strongly bipectinate, the pectinations long, untidily adpressed to the shaft, though this feature is not seen in Neotropical representatives (Pitkin, in press). Larvae are usually slender, the head capsule often distinctly cleft or bifid dorsally; the resting posture is stick-like.

Female genitalic features are typical of the Geometrini, though there are a few instances where the stucture of the signum is modified.

The concept of Hemitheiti recognised here embraces several other names listed in the section on family-group names: Thalerini (= Chlorochromini), Comostolini, Hemistolini, Jodini, Thalassodini. No clear indications of further subgroups have been detected, though a few generic groupings are noted in the main text following.

Genera included in Hemitheiti here are those from Aporandria Warren to Comostola Meyrick.

A few subtribes are not represented in Borneo. The Dichordophoriti were proposed by Ferguson (1969) to include a small number of New World taxa. The male genitalia have uncus and socii reminiscent of the Comibaeniti and Synchloriti, but the valve is unusual with strong ventral modification and also coremata, and the saccus is narrow, well developed, conical.

In addition, there are a few Bornean genera that do not fall readily into any of the categories above. These are treated at the end, commencing with Mystichlora Gen. n.

The Geometrini as a whole have larvae that are predominantly tree-or shrub-feeding and would be expected to be more diverse in forested or wooded ecosystems, as is in fact the case.

Within this arboreal feeding preference there are several groups where feeding on the reproductive parts of the host, or at least the young foliage, is common or prevalent: Nemoriiti, Comibaeniti, Hemitheiti, and to some extent the Pseudoterpniti.

The adults appear to fly particularly in and above the canopy in Bornean rain forest (Holloway, 1984a).