Two new species of Paramesosciophilodes (Diptera, Nematocera, Mesosciophilidae) from the Middle Jurassic of China.

Two new species, Paramesosciophilodesbellus sp. n. and Paramesosciophilodesrarissima sp. n., from the Jiulongshan Formation at Daohugou Village, Inner Mongolia, China, are described in the extinct family Mesosciophilidae. Altogether seven genera with 21 species of mesosciophilids have been described from the Jurassic of Siberia and Kazakhstan, the Lower Cretaceous of Transbaikalia, and the Middle Jurassic of Inner Mongolia. An emended generic diagnosis of Paramesosciophilodes and a list of known taxa of mesosciophilids are provided.

Introduction

is one of the extinct dipteran families of the suborder . Rohdendorf (1946) described a species, , which was assigned to a new subfamily, , within the family , along with . Later he implicitly synonymized with and excluded DeMejere, 1907 from the family (Rohdendorf 1957, PageBreak1962). Kovalev (1985) elevated to family level; and synonymized under the First Reviser Rule. Blagoderov (1993) erected the genus with three species within the family , and also revised the diagnosis of the . Two important generic characters of Kovalev, 1985, reported from the Middle Jurassic, are cell r distinctly large, longer than 1/6 of wing length, and r-m significantly shorter than bRs, which are regarded as “obvious ancestral characters” (Kovalev 1985). On the other hand, the generic features of Blagoderov, 1993, described from the Early Cretaceous, are cell r distinctly small, shorter than 1/6 of wing length, and r-m significantly longer than bRs, which are regarded as “derived characters” (Blagoderov 1993, Zhang 2002). Zhang (2007) established a monotypic genus for his new species, , and described another species within the genus . The generic diagnosis of includes cell r 0.16–0.18 times as long as wing length, bRs markedly shorter than r-m and R4+5 is strongly arched near its midlength. Later, Zhang (2008) assigned three new species to three genera, including Zhang, 2008, and reviewed all the records of mesosciophilids. Li and Ren (2009) described two species of from the late Middle Jurassic Jiulongshan Formation of Daohugou in southeastern Inner Mongolia, China. Species of Li & Ren, 2009 have cell r small, shorter than 1/6 of wing length, and r-m significantly shorter than bRs, which are regarded as “transitional characters” (Li and Ren 2009). Wang et al., in 2012, assigned two species respectively to and of (Wang et al. 2012). Shi et al. recently described a new genus with two new species, and , from the late Middle Jurassic of Jiulongshan Formation (Shi et al. 2014). To date, 7 genera and 19 species of mesosciophilids have been described from the Jurassic of Siberia and Kazakhstan, the Lower Cretaceous of Transbaikalia, and the Middle Jurassic of Inner Mongolia, which are summarized in Table 1. In addition, an emended generic diagnosis of , based on the new findings, is provided.

Table 1.

A list of the described fossil .

Genus	Species	Locality	Age
Mesosciophila	Mesosciophila venosa Rohdendorf, 1946	Karatau, Chimkent Oblast, Kazakhstan	Karabastau Fm., J3
	Mesosciophila eucalla Zhang, 2007	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
	Mesosciophila abstracta Zhang, 2008	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
	Mesosciophila sigmoidea Wang, Zhao & Ren, 2012	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
Mesosciophilodes	Mesosciophilodes augustipennis Rohdendorf, 1946	Karatau, Chimkent Oblast, Kazakhstan	Karabastau Fm., J3
	Mesosciophilodes similis Rohdendorf, 1964	Karatau, Chimkent Oblast, Kazakhstan	Karabastau Fm., J3
	Mesosciophilodes synchrona Zhang, 2008	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
Mesosciophilina	Mesosciophilina bolshakovi Kovalev, 1985	Siberia, Russia	Itat Fm., J2
	Mesosciophilina irinae Kovalev, 1985	Siberia, Russia	Itat Fm., J2
Mesosciophilopsis	Mesosciophilopsis curtus Blagoderov, 1993	Baissa, Buryat, Yeravnenskiy, Transbaikalia	Zaza Fm., K1
	Mesosciophilopsis expletus Blagoderov, 1993	Baissa, Buryat, Yeravnenskiy, Transbaikalia	Zaza Fm., K1
	Mesosciophilopsis minor Blagoderov, 1993	Baissa, Buryat, Yeravnenskiy, Transbaikalia	Zaza Fm., K1
Paramesosciophilodes	Paramesosciophilodes ningchengensis Zhang, 2007	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
	Paramesosciophilodes eximia Zhang, 2008	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
	Paramesosciophilodes aequus Wang, Zhao & Ren, 2012	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
	Paramesosciophilodes bellus Gao, Shi, Shih & Ren, sp. n.	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
	Paramesosciophilodes rarissima Gao, Shi, Shih & Ren, sp. n.	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
Jurasciophila	Jurasciophila curvula Li & Ren, 2009	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
	Jurasciophila lepida Li & Ren, 2009	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
Similsciophila	Similsciophila singularis Shi, Shih & Ren, 2014	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2
	Similsciophila sinuate Shi, Shih & Ren, 2014	Daohugou, Ningcheng, Inner Mongolia, China	Jiulongshan Fm., J2

(Notes: J2-Middle Jurassic, J3-Late Jurassic, K1-Early Cretaceous)

There have been many transfers and corrections regarding species belonging to the . Rohdendorf, 1946 from the Upper Jurassic of Kazakhstan might belong to the family (Blagoderov 1993). The Mongolian genus Kovalev, 1985 of the Lower Cretaceous should be transferred to the (Blagoderov 1993). The Australian species Jell & Duncan, 1986 should be transferred to an unnamed genus of rather than to the extant genus of Tonnoir, 1929 of (Blagoderov 1993), and we agree with this change. The genus Kovalev, 1990 from the Lower Cretaceous of Transbaikalia might belong to either the or to the (Blagoderov 1993). Hong, 1992 from the Lower Cretaceous of Kezuo has been transferred to the (Zhang 2008), but it might be a representative of . The other three species Hong, 1992, Ren, Lu, Guo & Ji, 1995 and Zhang, Hong & Li, 2001 from the Lower Cretaceous of China might belong to the family , PageBreakrather than to its previous assignment to the family of or the family (Zhang 2007).

Here, based on a combination of unique wing venational characters of two recently collected specimens, we describe sp. n. and PageBreak sp. n. These specimens with bodies and complete wings were collected from the late Middle Jurassic Jiulongshan Formation of Daohugou Village in the Ningcheng County, Chifeng City, southeastern Inner Mongolia, China. Many well-preserved fossil insects have been described from this locality recently (Ren et al. 2010, 2012), such as dipterans, neuropterans, orthopterans, heteropterans, etc. (Zhang et al. 2008, 2011; Wang et al. 2010; Gu et al. 2012; Yao et al. 2012).

Materials and methods

This study is based on two specimens housed in the Key Lab of Insect Evolution & Environmental Changes, Capital Normal University, Beijing, China (Curator: Dong Ren). The specimens were examined under a LEICA MZ12.5 dissecting microscope. The photos of fossils were taken with a Nikon SMZ1000 stereo microscope. Line drawings were prepared with the aid of CorelDraw 12 graphic software. The method of calculating the ratio of cell r length vs. wing length is as follows: the length of cell r is the length along R1, while the length of wing is the length from wing base to wing apex. Wing venation nomenclature follows that of Wootton and Ennos (1989) and Shcherbakov et al. (1995): bRs or dRs = section of R4+5 basal or distal to r-m, respectively; bM1+2 or dM1+2 = section of M1+2 basal or distal to r-m, respectively.

Systematic paleontology

Order Linnaeus, 1758 Suborder Latreille, 1825 Family Rohdendorf, 1946

Zhang, 2007

Type species.

Zhang, 2007.

Included species.

Type species; Zhang, 2008; Wang, Zhao & Ren, 2012; Gao, Shi, Shih & Ren sp. n., Gao, Shi, Shih & Ren, sp. n.

Emended diagnosis.

Medium (sized mesosciophilid gnats. Body (including legs) covered with long, dense pubescence. Mesonotum convex. Scutellum sharp, clearly projecting. Wing, Sc1 elongate, slightly shorter than one-half of wing length (0.43–0.47 times as long as wing length); Sc2 situated distinctly basad to Rs origin, arising near midway between h to Sc1 ending; bRs shorter than r-m; R1 slightly curved; both R1 and R4+5 divergent terminally; Rs furcated distad or at level of fork of M1+2; R2+3 oblique and curved; R4+5 arched near its midlength; cell r 0.16–0.19 times as long as wing length; stem of M not developed; M1+2 furcated slightly distad, or basad, to level of Sc1 ending. Tibiae and tarsi with sparse, short setae.

Gao, Shi, Shih & Ren sp. n.

http://zoobank.org/8FEE85B5-4556-40CA-8B60-B8309F5B1504

Figs 1 , 2

Figure 1.

sp. n., holotype, Photographs of habitus (dorsoventral aspect): A part No. CNU-DIP-NN2013631 p B counterpart CNU-DIP-NN2013631 c.

Figure 2.

sp. n., Line drawings of holotype: A part B wing venation.

Etymology.

The specific name is from the Latin of bellus, meaning beautiful and delicate, for the well-preserved and beautiful specimen.

Material.

Holotype No. CNU-DIP-NN2013631 p/c, part and counterpart. A well-preserved insect with complete body and two wings but poorly preserved halter, without head, in dorsoventral aspect.

Locality and horizon.

Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China, Jiulongshan Formation, late Middle Jurassic.

Diagnosis.

The Sc1 ending proximad of the midlength of cell r; bRs 0.7 times of the length of r-m; R4+5 strongly curved; M1+2 forking basad of forking of Rs, and distad of the level of Sc1 ending; CuA strongly arched, reaching the posterior margin of the wing markedly basad of Rs forking to R2+3 and R4+5.

Description of holotype.

Medium-sized mesosciophilid with dark body, adult male, in dorsal aspects (Figs 1 and 2A). Wings out-spread, length 5.4 mm, width 2.0 mm. Body length 7.2 mm. Head and antennae not preserved. Thorax convex, length 2.0 mm, width 1.3 mm. Scutellum clearly projecting. Abdomen thin, subcylindrical, length 5.2 mm, width 1.7 mm, approx. 2.6 times as long as head and thorax combined, with eight abdominal segments, first four segments gradually widened distally, last four segments gradually narrowed terminally. Partially preserved male genitalia relatively small, distinctly narrower than eighth abdominal segment. Halters poorly preserved. Legs relatively thin and long, femora clearly thicker in the middle; femora, tibiae and tarsi with two rows of sparse and short setae. Hind leg length 6.3 mm (femur 1.7 mm, tibia 2.4 mm, tarsus 2.2 mm).

Wings membranous, oblong, darker in color in costal area, moderately wide (length 2.7 times of width), and not reaching the apex of abdomen at rest (Fig. 2). C strong, ending beyond wing apex, at which R4+5 ending. Sc1 relatively long, approx. 0.4 times the length of wing, ending far distad of the intersection of bRs and r-m. Humeral vein distinct and oblique. Sc2 well developed, starting in front of bRs. Cell r distinctly small (0.89 mm), approx. 0.165 times the wing length (5.4 mm). Section of R from Sc2 to bRs origin approx. 2.4 times as long as bRs. R forking into three branches: R1, R2+3 and R4+5. R1 and R4+5 somewhat divergent terminally; R2+3 and R4+5 arched. Forking of Rs distad of the level of M forking. Rs strong, arising from beyond the basal one-third of length of wing, bRs+dRs nearly 0.4 times the R4+5. Rs forking to R2+3 and R4+5 distad of forking of M1+2. Section bRs 0.7 times the r-m. R1 slightly curved, relatively long (nearly 0.5 times the length of wing), slightly deflected after junction with R2+3; R2+3 slightly curved, shifted toward wing base, beyond the level of M1+2 forking. Vein R4+5 strongly arched near its midway, almost parallel with R1, but slightly oblique at apex. Stem of M completely reduced basad of crossvein m-cu, with only a short segment distad of m-cu. Stem of M forking into M1+2 and M3+4. M1+2 forking into M1 and M2 near R2+3 level. M1 arched anteriorly, M2 nearly straight. Crossvein r-m short, curved, slightly oblique, shorter than bRs, nearly perpendicular to M1+2, almost parallel to R2+3, intersected at M1+2, forking to bM1+2 and dM1+2. bM1+2 approx. 6.6 times as long as m-cu. dM1+2 approx. as long as bM1+2, and longer than r-m. CuA running parallel close to M3+4 basally. CuA reaching the posterior margin of wing at approx. the same level of M1+2 forking to M1 and M2. CuP short, slightly curved at its midway, not reaching the posterior margin of wing.

Remarks.

sp. n. resembles most closely , but can be distinguished from the latter in having Sc1 ending at C proximad of the miglength of cell r (vs. at the miglength of cell r for ) and CuA reaching the posterior margin of the wing markedly basad of Rs forking to R2+3 and R4+5 (vs. slightly basad of Rs forking to R2+3 and R4+5).

This new species is differentiated from , , , and sp. n. based on a combination of characters listed in Table 2.

Table 2.

Comparison of seven key characters of five species of .

	Paramesosciophilodes ningchengensis	Paramesosciophilodes eximia	Paramesosciophilodes aequus	Paramesosciophilodes bellus sp. n.	Paramesosciophilodes rarissima sp. n.
Length ratio of cell r and the wing	0.167 (left wing) 0.180 (right wing)	0.183 (left wing) 0.172 (right wing)	0.22 as described. But, the missing wing base was not included in wing length measurement.	0.165	0.184
Length of Sc1	46–47 % of the wing length	46% of the wing length	24% of the wing length as described. But, the missing wing base was not included in wing length measurement.	46–47% of the wing length	43% of the wing length
Sc1 ending at C	at the midlength of cell r	distad of midlength of cell r	proximad of midlength of cell r	proximad of the midlength of cell r	near the midlength of cell r
bRs vs r-m	0.6–0.7 times of length of r-m	0.5 times of the length of r-m	0.9 times of the length r-m	0.7 times of the length of r-m	0.8 times of the length of r-m
R4+5	slightly curved	slightly curved	strongly curved	strongly curved	strongly curved
The position of base of M1+2 forking vs the forking of Rs	M1+2 forking distinctly basad of forking of Rs	Ml+2 forking almost at level of forking of Rs	M1+2 forking basad of the forking of Rs	M1+2 forking basad of forking of Rs,	M1+2 forking basad of forking of Rs
The position of base of M1+2 forking vs the level of Sc1 ending	M1+2 forking basad or distad of the level of Sc1 ending	M1+2 forking at the level of Scl ending	M1+2 forking distad of the level of the Sc1 ending	M1+2 forking slightly distad of the level of Sc1 ending	M1+2 forking slightly distad of the level of Sc1 ending
CuA shape	CuA strongly arched	CuA smoothly arched	CuA smoothly arched	CuA strongly arched	CuA smoothly arched
CuA ending at the posterior margin vs. Rs forking to R2+3 and R4+5	CuA ending slightly basad of Rs forking to R2+3 and R4+5	CuA ending slightly distad of Rs forking to R2+3 and R4+5	CuA ending slightly distad of Rs forking to R2+3 and R4+5	CuA ending markedly basad of Rs forking to R2+3 and R4+5	CuA ending slightly distad of Rs forking to R2+3 and R4+5

Gao, Shi, Shih & Ren sp. n.

http://zoobank.org/2DC54917-79F7-4919-8B03-3BDA9BAF3B00

Figs 3 , 4

Figure 3.

sp. n., holotype, Photographs of habitus (dorsoventral aspect): A No. CNU-DIP-NN2013145 p B No. CNU-DIP-NN2013145 c.

Figure 4.

sp. n., Line drawings of holotype: A part B wing venation.

The specific name is from the Latin word of rarissimus, meaning rare.

Holotype No. CNU-DIP-NN2013145 p/c, part and counterpart. A well-preserved insect with complete body with two wings, without head and halters, in dorsoventral aspect.

Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China, Jiulongshan Formation, late Middle Jurassic.

Sc1 ending near the midlength of cell r; bRs 0.8 times the r-m; R4+5 strongly curved; M1+2 forking basad of R2+3 level and distad of level of Sc1 ending at C; CuA strongly arched, reaching the posterior margin of the wing at the level of intersection of Rs forking to R2+3 and R4+5.

Medium-sized mesosciophilid gnats, in dorsal aspect (Figs 3 and 4A). Body length (without head and part of thorax) 7.2 mm as preserved. Legs covered with long, dense pubescence. Head, antennae, and halters not preserved. Thorax length 1.8 mm, width 1.5 mm. Mesonotum convex. Scutellum sharp, clearly projecting. Wings membranous, oblong, length 5.0 mm, width 2.2 PageBreakPageBreakmm, darker in color in costal area, length 2.3 times width, and not reaching the apex of abdomen at rest. Abdomen thin, subcylindrical, length 5.4 mm, width 1.5 mm, with first five segments gradually widened distally, other segments gradually narrowed terminally. Legs poorly preserved, femora thicker in the middle, covered with numerous setae.

C strong, ending beyond wing apex, at which R4+5 ending (Fig. 4). Sc converging with C before the level of R4+5. Sc1 elongate, slightly shorter than one-half of wing length (0.43–0.47 times the wing length), and ending far distad of the intersection of bRs and r-m. Vein h distinct and oblique. Sc2 developed well, starting in front of Rs, situated distinctly basal to Rs origin, arising beyond midway between h to Sc1 ending. Cell r relatively large (0.92 mm), approx. 0.18 times the wing length (5.0 mm). The section of R from Sc2 to Rs origin approx. 0.7 times the section bRs. R forking to R1 and Rs, then Rs to R2+3 and R4+5. Both R1 and R4+5 somewhat divergent terminally; R2+3 and R4+5 arched. Rs usually strong, arising from basal one-half of length of wing, forking to R2+3 and R4+5 beyond the forking of M1+2. Section bRs 0.8 times the r-m. R1 slightly curved, relatively long, nearly 0.5 times the wing. Both R1 and R4+5 divergent terminally. R2+3 curved, beyond the level of M1 and M2 forking. R4+5 strongly arched near its midlength. Stem of M, basad to crossvein m-cu completely reduced, with only a short segment distal to m-cu. Stem of M forking into M1+2 and M3+4. M1+2 forking into M1 and M2 basad of R2+3 level and distad to level of Sc1 ending at C. M1 arched cephalad. M2 nearly straight. Crossvein r-m short, curved, slightly oblique, shorter than bRs, r-m intersecting M1+2 and dividing M1+2 into bM1+2 and dM1+2. Section bM1+2 approx. 4.3 times the crossvein m-cu. Section dM1+2 approx. 1.2 times the section bM1+2, and longer than r-m. CuA running parallel and close to M3+4 basally. CuP short, slightly curved midway, reaching the posterior margin of wing at the same level as Sc1 ending at C.

sp. n. is distinguished from all other species of based on a combination of characters listed in Table 2.

Discussion

As shown in Table 1, a total of 7 genera and 21 species of mesosciophilids have been reported from various localities in the Jurassic of Siberia and Kazakhstan, Lower Cretaceous of Transbaikalia, and Middle Jurassic of Inner Mongolia. One genus with 2 PageBreakspecies was described in the Middle Jurassic Itat Formation, Siberia; 6 genera with 13 species were reported from the Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China; 2 genera with 3 species were described from the Late Jurassic Karabastau Formation in Kazakhstan; and one genus with 3 species was documented from the Early Cretaceous Zaza Formation at Baissa, Transbaikalia.

The data show that the known earliest mesosciophilids have been reported from the Middle Jurassic, while the latest ones are described from the Early Cretaceous. It seems that mesosciophilids became less diverse in the Early Cretaceous, and were possibly replaced by (Blagoderov 1993), which is supported by Zhang’s data, who listed all the mesosciophilids and mycetophilids from Daohugou, and compared them with other faunas (Zhang 2002).