晚侏罗世摇蚊科新属、种

NEW GENERA AND NEW SPECIES OF CHIRONOMIDAE (DIPTERA, INSECTA) FROM LATE JURASSIC OF CHINA

本文描述了我国冀北和鲁东上侏罗统摇蚊科化石3属、3种,其中,1新属和3新种。冀北大北沟组中不存在Chironomaptera gregaria种化石,以前被鉴定为幽蚊科的这个种实际上应为摇蚊科的1个新种。并对如何区分上侏罗统这两个科成虫化石作了简述。

The Mesozoic chironomid midges have been discovered from Transbaikalia and Taymyr of Russia, Mongolia, West Europe and Canada. Only a few species have been described from China so far. Ping (1928) and the present writer and others (1985) separately published a single species from Liaoning and Shandong Provinces. In fact, there are many kinds of the family Chironomidae from China, especially in the 'Jehol Fauna'. However, there exist different opinions on their systematic position. For example, an undoubted phantom midge Chironomaptera gregaria (Grabau) was usually placed in Chironomoidea, while a pure chironomid midge Manlayamyia dabeigouensis sp. nov. described in this paper was usually regarded as an element of Chironomaptera gregaria. Kalugina (1985) set up a key to the Jurassic pupae of chironomid midges and phantom midges, but she did not illustrate ltow to distinguish the adults of the former from those of the latter, because it seems too difficult to sum up the imaginal diagnostic characters based on the ill-preserved wing or the indistinguishable wing venation iv the specimen. Judging from the known materials and collected specimens in hand, it appears to the present writer that there are certain differences between both families as remarked above. In the family Chironomidae, the male adults have an obviously narrow and elongate body, but the females are much stouter and shorter. The head is usually covered by thorax completely or nearly so. The antenna comprises more or less than fourteen segments in number and is distinctly different in feature from that of phantom midges, such as the genera Chironomaptera Ping and Chaoborus Lichtenstein. The distance is very short from the fork of veins R and Rs to the end of vein R while veins C, R and Rs show clearer and stouter than veins M, CuA and A, if its wing had been preserved and the veins could be distinguished in part. The Jurassic imaginal specimens of chironomid midges, for the most part, bear these characters mentioned above, but sometimes with some exceptions. This paper describes a single new genus and three new species. The specimens' were collected by the present writer and others separately from the Dabeigou Formation of Hebei in 1980 and the Laiyang Formation of Shandong in 1984 and are now conserved in the Shandong Provincial Museum. Description of New Genera and New Species Superfamily Chironomoidea Macquart, 1838 Family Chironomidae Macquart, 1838 Genus Manlayamyia Kalugina, 1980 Manlayamyia dabeigouensis sp. nov. (Pl. Ⅰ, figs. 1, 2; Pl. Ⅱ, figs. 1—4; Pl. Ⅲ, figs. 3, 4; Text-figs. 1—3) 1982 Mesotendipes gregaria, Hong, pp. 162—166, Pl. 36, figs. 1, 2. 1984 Mesotendipes gregaria, Hong, p. 175. Male adult Body narrow and elongate. Head small, oval and completely covered by thorax. Eyes large, elongately kidney-shaped. Antennae rather thin, filiform, with not less than 18 segments, somewhat longer than head; scape oval, extremely expanded, and remainder oblong, each about twice(?)as long as wide, clothed with strongly plumose and bushy hairs. Proboscis a little elongate, nearly as long as head. Maxipalp with 5 segments (0.32, 0.28, 0.35, 0.26, 0.37mm), about 1.6 times as long as head. Thorax short and massive, distinctly wider and thicker than abdomen, with feature of scierite shown in text-fig. 2A. Legs thin and long; anterior legs obviously longer than middle and posterior ones, usually extending forward. Coxae 1/3 as long as femora. Anterior femora nearly as long as tibiae; tarsi with 5 segments (1.3, 1.2, 0.8, 0.6, 0.5mm), 2.3 times as long as tibiae, while basitarsi 2/3 as long as tibiae. Posterior femora shorter than tibiae, with tarsi 1.5 times as long as tibiae, while basitarsi about 1/2 as long as tibiae. Abdomen elongate-cylindrical, with 9 segments, 5.2 times as long as wide; each segment transverse, with the 8th segment somewhat narrower than the 7th and about as long as wide. Hypopygium distinct, with covite small, 1.4 times as long as wide; style cheliferous, 3/4 as long as covite, distinctly tapered, and strongly pointed. Holotype Body 7.9mm, head 0.6mm, thorax 2.0mm, abdomen 5.3mm, maxipalp 1.Smm, anterior leg 8.2mm and posterior leg 7.8mm (in length). Female adult Body rather short and stout. Head transverse (dorsal aspect), oblong (lateral aspect). Eyes large. Antennae with not less than 14 segments, a little longer than head; scape somewhat expanded, and remainder without hairs, each transverse. Maxipalp with 5 segments (0.30, 0.25, 0.28, 0.33, 0.35mm), 2.3 times as long as head. Thorax oval, faintly wider than head. Anterior basitarsi about 2/5 as long as tibiae, and dlsttinctly longer than the second segment. Wing nat- row and long; its top far beyond apex abdominis. C straight; R short; Rs simiple and straight at the top of wing. Others rather thin and faint, indistinguishable. Abdomen short and massive, twice as long as wide, somewhat narrower than thorax,with 9 segments, each rather transverse, less than 1/3 as long as wide; 8th segment likely possessing circular spermatheca, while 9th one rather small; style of hypopygium elongate-triangular and curved inward (dorsal aspect), obtuse-triangular (lateral aspect). Paratype Body 6.2mm by 2.1mm in size; head 0.6mm, thorax 2.3mm, abdomen 3.3mm and anterior leg about 7.5mm in length. Pupae Cephalothorax oval, a little wider than abdomen. Abdomen 7 segmented, cylindrical; each segment transverse, without hairs; last segment triangular, nearly as long as wide. Style small, elongate-triangular. Paratype Body 8.5mm by 2.3mm. Remarks and Comparison Hong (1982) considered that these specimens from the Dabeigou Formation of Hebei could be placed in Chironornaptera gregaria (Grabau) and thus the name of Chironomaptera was inconsistent with the features of the specimens; then he suggested to replace Chironomaptera by Mesotendipes. In the present writer's opinion, the name of Mesotendipes is invalid and should be abolished. Since the specimens described in this paper have noticeably different features from those of Chironomaptera gregaria, both of them cannot be placed in the same superfamily. This new species is very closely similar to M. litorina Kalugina, but differs from the latter in having a somewhat stout and short body which is 4.0 to 4.5 times as long as wide; more massive thorax which is distinctly wider than abdomen; longer antennal flagellum with strongly plumose and bushy hairs; and shorter last abdominal segment of pupa. Horizon and Locality Dabeigou Formation, Lahaigou, Luanping, Hebei. Genus Oryctochlus Kalugina, 1985 Oryctochlus contiguus sp. nov. (Pl. Ⅱ, fig. 5; Pl. Ⅲ, figs. 1, 2; Text-figs. 4, 5) Male adult Head entirely covered by thorax, invisible from dorsal aspect. Antennae slightly longer than thorax, with 13 segments; scape globately expanded; basal segments perlate, and remainder oblong, armed with strongly plumose and bushy hairs. Thorax short and wide, nearly quadrate, distinctly wider than abdomen. Legs rather thin and long. Anterior femora shorter than tibiae; tarsi extraordinarily long, with terminal part missing, and first tarsal segment only a little shorter than tibiae. Posterior legs obviously longer than abdomen, with femora somewhat shorter than tibiae; tarsi 1.5 times as long as tibiae, with 5 segments (0.84, 0.37, 0.30, 0.30, 0.30mm); spur rather short. Abdomen narrow and long, 3.5 times as long as thorax, narrowing terminally; each abdominal segment wider than long, with 9th one about twice as wide as long. Hypopygium lanceolate. Wings short and wide, not reaching to apex abdominis, with veins extremely thin. C somewhat arched, running to the end of Rs. R short, with a shorter distance from fork of R to the end of R than r-m. Basal part of Rs (from fork of R to r-m) rather short, about 1/7 as long as r-m, and vertical between R and terminal part of Rs. M and CuA extremely thin, indistinguishable. Holotype Body 4.57mm in length and 1.00mm in width; thorax 1.00mm, abdomen 3.50mm and wing 2.74mm in length. Female adult Body narrow and short. Head transverse, 2.4 times as wide as long (excluding proboscis). Eyes obviously large, oval. Proboscis short, about a half as long as head. Thorax short, slightly wider than abdomen, longer than wide. Legs thin and long. Anterior legs ill-preserved. Pos- terior legs distinctly longer than abdomen, with femora a little shorter than tibiae; tarsi 1.4 times as long as tibiae, with 5 segments (0.51, 0.27, 0.20, 0.17, 0.17mm). Abdomen narrow and long, cylindrical, 2.2 times as long as thorax; each abdominal segment transverse. Apex abdominis with style large, pincers-like. Wings long, reaching to apex abdominis, with veins extremely thin, and venation closely similar to that of male adults. Paratype Body 2.98mm in length and 0.75mm in width; head (excluding proboscis) 0.20mm, thorax 0.91mm, abdomen 2.06mm and wing 2.37mm in length. Comparison Oryctochlus contiguus sp. nov. has a close affinity to O. vulcanus Kalugina, a Middle-Upper Jurassic species from Transbaikalia, but in the male adults of the former the basal antennal segments are perlate, with remainder oblong, both the 4th and 5th tarsal segments of posterior legs are equal in length, and the body is large in size; while in the female adults of the former, the body is narrow, both the 4th and 5th tarsal segments of posterior legs are equal in length, and the style is large. Horizon and Locality Laiyang Formation, Tuanwang, Laiyang, Shandong. Genus Sinoryctochlus gen. nov. Type species Sinoryctochlus insolitus gen. et sp. nov. Body minute. Head large. Antennae of male short, 11-segmented, with few and scattered short hairs. Legs thin and long, with anterior basitarsi 2/3 as long as tibiae. Hypopygium large; style cheliferous. Wings short. Rs simple; basal part of Rs nearly as long as r-m. Basal part of posterior branch of M and m-cu indistinguishable. Comparison This new genus is close to Manlayamyia Kalugina, but may b