Synegiodes Swinhoe, 1892

Cui, Le, Jiang, Nan, Stüning, Dieter & Han, Hongxiang, 2018, A review of Synegiodes Swinhoe, 1892 (Lepidoptera: Geometridae), with description of two new species, Zootaxa 4387 (2), pp. 259-274 : 260-261

Synegiodes Swinhoe, 1892

Synegiodes Swinhoe, 1892 , Trans. ent. Soc. Lond. 1892: 11. Type species: Anisodes sanguinaria Moore, 1868 . (here fixed under Article 70.3 of the Code, misidentified as Anisodes diffusaria Moore, 1868 in the original designation by Swinhoe (1892).

Synegioides Swinhoe, 1893 , Ann. Mag. nat. Hist. (6) 12: 150. An incorrect subsequent spelling.

Generic characters. Moths of moderate size, wingspan roughly between 25 and 35 mm. Species of Synegiodes are superficially similar to members of the ennomine genera Synegia Gueneé , Yashmakia Warren or some species of Parasynegia Warren externally, but are distinguished by the discal spot which is white-centred and ringed black on outer edge in Synegiodes [but some Parasynegia also have discal spots with white centre] (besides other evident differences between the subfamilies) ( Holloway 1997). Wings broad, apex of forewing moderately pointed, termen waved between the vein ends, moderately projecting at end of vein M3 (more strongly so in the hindwing). Pattern consisting of transverse, more or less inclined, sometimes interrupted lines or bands of variable shape, antemedial line absent or weak in all species (if present, indicated by a few black dots on veins only). Coloration grey or brown, in some species pinkish or red on yellow or orange ground color. Discal spots distinct, consisting of a black circle with a white center, larger in the hindwing in all but one species.

Head. Antennae bipectinate, with terminal 1/4–1/3 filiform in male, rami long and narrow, dorsally not scaled, with rows of long sensillae; filiform, very shortly setose (pubescent) in female. Frons broad (broader than compound eyes in frontal view), smooth-scaled (scales very small), roundly protruding, lateral margins steep (less expressed in females). Vertex with slightly larger, contrastingly colored, smooth scales, pure white and shining in almost all species. Chaetosemata present near margin of compound eyes, but consisting of a few setae only. Labial palpi rather short and porrect in males, curved upwards in females, third segment slightly (in males) or distinctly (in females) extending beyond frons. Proboscis well developed. Thorax. Patagia and tegulae covered with larger, lamellar scales of different colors, distal scales of tegulae elongate, only very few hair-like. Hind tibia long, with two pairs of spurs in both sexes, not dilated and without hair-pencil in male. Tarsal segments not modified in males. Posterior surface of metathorax, opposite to the tympanal opening, covered with a large, scaled, sometimes folded membrane in males (Fig. 45), rarely with a brush of elongate scales outside. Frenulum well developed in both sexes. Forewing with one elongate or two smaller areoles (i.e., in the latter case, the elongate areole is divided by the -still present- base of vein R2). Prout (1918) used this character to separate the genus into two species-groups.

However, the venation of both wings is considerably variable, interspecific as well as intraspecific, especially in relation to the veins branching off from areole (but not in relation to the number of areoles). The common stalk of the veins R2–4 is always arising from the apical angle of the areole, but the veins R1 and R5 can arise proximally or distally or directly from the apical angle of the areole, or the origin of both may even be different in both wings in the same specimen. Veins M3 and CuA1 are not stalked. In the hindwing, the veins Rs and M1, and M3 and CuA1 are short-stalked or not stalked, sometimes stalked only in one of the two pairs. Pregenital abdomen. Tergites and sternites weakly sclerotized (tergites 1 and 2 and sternite 1+2 slightly stronger so), without modifications; tympanal organs without laciniae, ansa hammer-headed; sternite 3 without setal comb. Male genitalia. Uncus very broad at base, truncate or slightly bilobed at apex in a group of four species including the type-species; long and thin in the remaining five species. In the latter species-group, large “socii” ( Holloway 1997) of variable shape arise from the posterior portion of the tegumen. Gnathos absent. Valva narrow at basal half, even narrower distally, costa well sclerotized until tip, the latter with strong, curved setae; sacculus with a small process, pointed or rounded at tip, arising more or less from the middle of the ventral margin of valves. Juxta elongate, often constricted centrally. Anellus sclerotized, ring like, sometimes with a process or a rim on posterior margin. Aedeagus narrow (e.g. Fig. 29), vesica narrow and simple or aedeagus larger and broader (e.g. Fig. 30), vesica voluminous and composed of several diverticula. Cornutus-like structures or sclerotized bands always present (absent in brunnearia ). Male genitalia of S. brunnearia distinctly different in most characters ( Fig. 25 ). Female genitalia. Apophyses anteriores roughly about 1/2 as long as apophyses posteriores, weak and narrow, moderately strong, or short and stout. Lamella postvaginalis not or only weakly sclerotized, triangular or appearing as an irregular, longitudinal plate. Two species ( histrionaria , expansus ) with more conspicuous sclerotization. Lamella antevaginalis a narrow, arched bridge between the antero-ventral angles of genital segment in most species. Ostium sometimes surrounded by a wide ostial funnel, the latter weakly sclerotized. Colliculum developed in all species, varying in size. Ductus bursae abruptly widening near colliculum, with diverticula of variable size distally, then moderately wide or as wide as corpus bursae, both often not separable from each other. Signum composed of a narrow, longitudinal sclerotized rib, set on a slightly sclerotized, flat plate of variable shape, anteriorly bent inwards and forming a triangular pouch in the bursa wall (all except hyriaria and elasmlatus in which the signum is shaped differently and the pouch is absent).

Remarks. On the basis of essential differences of the male genitalia, members of Synegiodes , as it is currently defined, are divided into two species-groups, either of which may be monophyletic. The first group consists of four species, sanguinaria , punicearia , histrionaria and ornata stat. rev. All these species have very broad, stout, distally truncate or slightly bilobed, strongly sclerotized uncus, but lack teguminal processes (“socii”). We refer to this group as the “ sanguinaria group”. The second group consists of five species, obliquifascia , diffusifascia , expansus sp. nov., hyriaria and elasmlatus sp. nov., in which the male genitalia are characterized by the presence of a narrow, elongate uncus and conspicuous processes diverging from the posterior part of the tegumen, stretching ventrally like gnathal arms in their natural position (“socii” sensu Holloway 1997). We refer to this group as the “ obliquifascia group”. These two groups also can be differentiated by the wing pattern: the species of the sanguinaria group are more or less tinged with pink, the medial line on the forewing is indistinct, and that on the hindwing is only represented by a short patch (except in ornata ); the members of the obliquifascia group are not tinged with pink, and the brown medial line is distinct on both, fore- and hind wings. Such essential differences are usually not found among species of the same genus and the question turned up whether a new genus was necessary for the reception of the obliquifascia group.

Prout (1918) turned the attention to the existence of one or two areoles in the forewing venation of different species, and later he separated the species of Synegiodes into two sections, based on this character (Prout 1938). One section includes sanguinaria , diffusifascia , histrionaria , ornata , punicearia and expansus sp. nov. which have one areole, and the other species, obliquifascia , hyriaria and elasmlatus sp. nov., have two areoles, i.e. the resulting subdivision is a different one, compared to the use of wing pattern and male genitalia for separation of the groups.

Considering the similarity of other parts of the male genitalia, such as valva, juxta, anellus, aedeagus, and those of the female genitalia across both species-groups, we believe that it is not justified to separate the species of Synegiodes into different genera.

Distribution. Oriental tropics and subtropics.

Figures

FIGURES24–25. Male genitalia. 24.S. elasmlatus(paratype, IZCAS), China, Yunnan; 25 S. brunnearia, China, Sichuan.26– 35. Aedeagi. 26. S. sanguinaria, China, Yunnan; 27. S. punicearia (holotype, IZCAS), China, Sichuan; 28. S. histrionaria, China, Tibet; 29. S. ornata, China, Taiwan; 30. S. diffusifascia (paratype, ZFMK), N. India, Khasi Hills; 31. S. expansus (holotype, IZCAS), China, Guangdong; 32. S. obliquifascia, China, Tibet; 33. S. hyriaria, China, Tibet; 34. S. elasmlatus (paratype, IZCAS), China, Yunnan; 35. “S”. brunnearia, China, Sichuan. Scale bars = 1 mm.