Mesoplecia plena, Lin, Xiuqin, Shih, Chungkun & Ren, Dong, 2014

Lin, Xiuqin, Shih, Chungkun & Ren, Dong, 2014, Two new species of Mesoplecia (Insecta: Diptera: Protopleciidae) from the late Middle Jurassic of China, Zootaxa 3838 (5), pp. 545-556 : 547-552

Mesoplecia plena sp. nov.

( Figs. 2–5 )

Diagnosis. A combination of these characters: crossvein sc-r absent; Sc reaching anterior margin at the level of rm; R2+3, strongly sigmoidly curved, reaching anterior margin very close to the position of R1 apex; R2+3 about half of R4+5; dRs more than half of R2+3; bRs 1.1–1.5 times as long as dRs; and dM1+2 shorter than r-m; legs relatively thin and slender; femur slightly thicker than tibia.

Etymology. The specific name is derived from Latin adjective “plenus”, indicating the abdomen segments III–V are plump.

Description. Head: Oviform, in dorsal view, with compound eyes, big and oval. Antennae filiform, more than twice of head length. Maxillary palpi barely visible.

Thorax: Prothorax barely visible; anterior part of scutum in mesothorax arched convex in lateral view and large and oval in dorsal view; and metathorax slightly depressed in lateral view.

Legs: Forelegs relatively thin and slender. Femur slightly expanded, covered with dense setae, tibia long and slender, longer than femur; 1st tarsomere slightly shorter than tibia; 2nd to 4th tarsomere gradually thinned; the claws small. Mid legs similar to forelegs, slightly longer than forelegs, tibia longer than femur; femur thicker than tibia; tibial spur well developed; with two pretarsal claws. Hind legs: femur slightly expanded; tibia longer than femur, first tarsomere distinctly longer than first tarsomeres of fore and mid legs, with two claws at apex of pretarsi.

Wings: Wings long and narrow; wing length 6–7.5 mm, width 2.6–2.8 mm. Apex of wings covering the abdominal terminalia ( Figs. 3 A and 3B) or not covering the abdominal terminalia ( Figs. 2 A, 4A and 5A); humeral vein h well developed, straight and short; R2+3 strongly sigmoidly curved; pterostigma close to oval; Rs arising from basal one–third wing length, furcated slightly distad of the level of M1+2 forking; stem of Rs longer than R2+3; R4+5 weakly curved upward medially and twice the length of R2+3, ending below apex of wing; bRs 2.6–3.1 times as long as r-m; M2 6.3–7.5 times as long as dM1+2; M1, longer than M2, almost equal to M3+4; crossvein r-m about the length of m-cu, almost at level of Sc ending; ratio of bM1+2/dM1+2 about 2.2; CuA strongly curved, ending at posterior margin of wing proximad of mid wing.

Abdomen: In female, the 1st tergite much narrower than the 2nd tergite; the 3rd to 5th tergite widest, 6th to 8th tergite gradually thinned; the 9th sternite combined with genitalia, undivided, with cerci apically ( Figs. 2–3 ). In male, abdomen cylindrical; genitalia slightly narrower than abdomen; with gonocoxites projecting, almost fused with 9th segment; gonostylus depressed, small and slightly cylindrical ( Fig. 4 ).

Remarks. The morphological differences among the species of Mesoplecia , based mostly on characters of wing venation, are summarized in Table 1 . The new species is similar to M. stigma Rohdendorf, 1962 but differs in having crossvein sc-r absent (vs. present); bM1+2 about 2.2 times as long as dM1+2 (vs. 1.36); and dM1+2 shorter than r-m (vs. longer). The new species differs from M. jurassica Rohdendorf, 1938 and M. sinica Zhang, 2007 in having R2+3, strongly sigmoidly curved, reaching anterior margin very close to the position of R1 reaching anterior margin (vs. R2+3, sigmoidly curved, reaching anterior margin distad of the position of R1 apex); R2+3 shorter than bRs and dRs combined (vs. R2+3 as long as bRs and dRs combined); and bRs 1.1–1.5 times as long as dRs (vs. 2.45 in M. jurassica and 2 in M. sinica ). Comparisons with other species are listed in the Table 1 .

Type materials. Holotype, ♀, No. CNU-DIP-NN2013048 ( Fig. 2 ), almost complete fossil of a female in dorsal view, with well-preserved body, but only the right forewing venation clearly discernible. Paratypes: ♀, No. CNU-DIP-NN2013052 p/c ( Fig. 3 ); ♂, No. CNU-DIP-NN2013050 ( Fig. 4 ) and ♀, No. CNU-DIP-NN2013098 ( Fig. 5 ). All type specimens are deposited in the Key Laboratory of Insect Evolution and Environmental Changes, Capital Normal University.

Measurements (in mm). Holotype: ♀, CNU-DIP-NN2013048 [data for the holotype in brackets]. Body length (including head) 8.4–10.7 [10.7], maximal width of body 1.37–1.9 [1.9]; antenna length 1.5 as preserved for segments 1–11 in CNU-DIP-NN2013050, 2.4 as preserved for segments 1–15 in CNU-DIP-NN2013098 [2.2 as preserved for segments 1–12]. Foreleg: 1.5–1.8 [0.5 as preserved]; tibia 2–2.6 [2.5]. Mid leg: femur 1.5–2 [1.1 as preserved]; tibia 2.6–3.5 [2.6]. Hind leg: femur 2–2.8 (2 as preserved); tibia 3.5–4.7 [3.7]. Wing: length 6–7.5 [7.1], width 2.6–2.8 [2.8]; R1 2.5–3.4 [3.1]; R2+3 1.1–1.5 [1.4]; bRs 0.95–1.1 [1.1]; dRs 0.65–1.1 [0.94]; R4+5 2.3–3 [2.7]; r-m 0.32–0.44 [0.4]; m-cu 0.26–0.45 [0.32]; bM1+2 0.6–0.8 [0.78]; dM1+2 0.28–0.4 [0.35]; M1 2.4–3.4 [2.9], M2 2.1–2.5 [2.3]; pterostigma: length 0.55–0.9 [0.9], width 0.35–0.5 [0.5].

Horizon and locality. All specimens were collected from the Jiulongshan Formation, late Middle Jurassic age (Bathonian–Callovian boundary interval) from Daohugou Village, Ningcheng County, Inner Mongolia Autonomous Region in China.

Note 1: Data of M. anfracta are from the right wing of holotype in Figs 1 and 5 of Hao and Ren, 2009.

Note 2: Abbreviations: 1. YES = Present; 2. NO = Not present; 3. SL = Sc reaching anterior margin at or near the same level with r-m; 4. PX = Sc reaching anterior margin proximad of r-m; 5. NA = Not available; 6. DS = R2+3reaching anterior margin distad of R1 apex; 7. S-N = R2+3 reaching anterior margin very close to the position of R1 apex; 8. WL = Wing length (mm); 9. L/ W = The ratio of wing length to width.

Figures

FIGURE 1. Representative species of genera in Protopleciidae, Line drawings of wings. A— Archipleciomima obtusipennis Rohdendorf, 1962 (from Blagoderov 1996 based on Rohdendorf 1964); B— Mesoplecia plena sp. nov. (this study); C— Epimesoplecia shcherbakovi Zhang, 2007 (from Zhang 2007); D— Mesoplecia jurassica Rohdendorf, 1938 (from Rohdendorf 1938); E— Mesopleciella minor Rohdendorf, 1946 (from Rohdendorf 1946); F— Palaeoplecia rhaetica Rohdendorf, 1962 (from Blagoderov 1996 based on Rohdendorf 1962); G— Protoligoneura fusicosta Rohdendorf, 1962 (from Blagoderov 1996 based on Rohdendorf 1964); H— Protoplecia liasina Geinitz, 1884 (from Ansorge 1996). Scale bars = 1 mm.

FIGURE 2. Holotype of Mesoplecia plena sp. nov. (CNU-DIP-NN 2013048). A—Photograph of holotype; B—Line drawing of holotype; C—Line drawing of right wing; D—Details of part of legs. Scale bars = 1 mm.

FIGURE 3. Paratype of Mesoplecia plena sp. nov. (CNU-DIP-NN 2013052 p / c). A, B—Photographs of part and counterpart; C, D—Line drawings of part and counterpart; E—Details of femur; F—Details of left wing. Scale bars = 1 mm.

FIGURE 4. Paratype of Mesoplecia plena sp. nov. (CNU-DIP-NN 2013050). A—Photograph; B—Line drawing. Scale bars = 1 mm.

FIGURE 5. Paratype of Mesoplecia plena sp. nov. (CNU-DIP-NN 2013098). A—Photograph; B—Line drawing. Scale bars = 1 mm.

Tables

TABLE 1. Comparison of characters for all described species of Mesoplecia Rohdendorf, 1938.

Species	sc-r	Sc vs. r-m	WL (mm)	L/W	bRs/r-m bRs/dRs
M. jurassica Rohdendorf, 1938	NO	SL	7	2.2	3.2 2.45
M. stigma Rohdendorf, 1962	YES	SL	8.13	2.3	3.5 1.2
M. sibirica Kovalev, 1985	NO	PX	NA	NA	2.97 NA
M. oleynikovi Kovalev, 1990	NO	PX	6.4	2.4	2.9 1.7
M. sinica Zhang, 2007	NO	SL	7.2	2.2	2.9 2
M. mediana Zhang, 2007	NO	SL	5	2	3.75 1.3
M. anfracta Hao & Ren, 2009	NO	PX	7.5	2.5	3.3 1.3
M. coadnata Hao & Ren, 2009	NO	PX	6	2	2.8 1.4
M. plena sp. nov.	NO	SL	6–7.5	2.3–2.7	2.8–3.1 1.1–1.5
M. fastigata sp. nov.	YES	SL	7	2.5	3.67 1.2
TABLE 1. (Continued)