Description of the specimens
Order Coleoptera Linnaeus, 1758
Family Ommatidae Sharp et Muir, 1912
Subfamily Ommatinae Sharp et Muir, 1912
Tribe Ommatini Sharp et Muir, 1912
Genus Pareuryomma Tan, Ren, Shih et Ge, nom. nov.
Pareuryomma
Tan, Ren, Shih
et
Ge, 2006 (nect. Stein, 1899) nom. nov.
Pareuryomma
nom. nov., for
Euryomma
Tan, Ren, Shih
et
Ge 2006 (Coleoptera: Archostemata) nect. Stein, 1899 (Diptera: Fanniidae).
Type species
Pareuryomma tylodes (Tan, Ren, Shih et Ge, 2006) comb. nov.
Included species
Pareuryomma tylodes (Tan, Ren, Shih et Ge, 2006) comb. nov., P. ancistrodonta sp. nov., and P. cardiobasis sp. nov.
Emended diagnosis
Whole body surface with large round tubercles, especially on head and prothorax; dorsal head surface without macroscopic tubercles. Mandibles prominent, incurved, with vertically arranged teeth. Antennae not reaching posterior margin of prothorax, 11-segmented, antennomeres 7–10 very slightly extended, resulting in a slightly serrated appearance of this part of antenna; apical flagellomere short and wide, apically rounded, appearing inflated. Pronotum widest anteriorly, narrowing posteriorly; anterior angles moderately produced. Elytra very distinctly convex basally, flattened towards apex, with 8 rows of cells on disc; epipleural space wide anteriorly, narrowing towards apex; with 2 rows of cells in the proximal half and one row in the apical half; principal longitudinal veins parallel to the sutural margin. Abdominal sternites arranged in one plane. First visible ventrite longest, last visible ventrite (=sternite VII) about 1.4 times as long as preceding one.
Note
The emended diagnosis is based on the type species and the new materials.
Occurrence
Type species and Pareuryomma cardiobasis sp. nov. are from the Early Cretaceous Yixian Formation, near Chaomidian Village, Beipiao City, Liaoning Province, China. Pareuryomma ancistrodonta sp. nov. is from the Middle Jurassic Jiulongshan Formation, Daohugou, Ningcheng, Inner Mongolia, China.
Remarks
The genus Euryomma was erected by Tan, Ren, Shih et Ge [34]. However, the name has already been used previously to describe flies of the family Fanniidae (Euryomma Stein, 1899 (type species: Anthomyia peregrine Meigen, 1826 (= Euryomma hispaniense Stein, 1899)) [42]. Consequently, the beetle genus Euryomma became the homonymy of Euryomma of the family Fanniidae. Based on the “International Code of Zoological Nomenclature (fourth edition)”, we amend the genus name from “Euryomma” to “Pareuryomma”.
Kirejtshuk et al.[41] considered Pareuryomma as a synonym of Notocupes Ponomarenko, 1964. The new fossil specimens clearly show that this genus is distinctly different from Notocupes. Pareuryomma can be distinguished from Notocupes by the following characters: dorsal head surface without longitudinal bulge or keel; antennae moniliform, antennomeres 7–11 widened distally; pronotum widest anteriorly, narrowing posteriorly; abdominal ventrites arranged in one plane, not overlapping.
Pareuryomma ancistrodontasp. nov.
Diagnosis
Mandible with one apical tooth; temples shorter than eyes; anterior edge of pronotum distinctly curved inwards; anterolateral edge of pronotum rounded; central disc with 2 flat elevations.
Etymology
Name derived from the Greek compound word ‘ancistrodonta’, -a, -um, (with falcate tooth), referring to the sickle-shaped mandible.
Type material
Holotype: a well-preserved adult with body, elytra, and parts of legs and antennae. Registration No. CNU-C-NN2010808, housed in Key Lab of Insect Evolution & Environmental Change, Capital Normal University, Beijing, China.
Type locality and horizon
Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China; Jiulongshan Formation, Middle Jurassic (Bathonian- Callovian boundary).
Description
Body small, surface densely covered with tubercles (Figure 5A).
Head capsule: with distinctly protruding compound eyes approximately as wide as long; distinctly narrower anteriorly and posteriorly than at ocular region and temples; distinctly prognathous; without raised tubercles or longitudinal bulge or keel on dorsal surface; anterior margin very slightly convex; frontoclypeal suture not recognizable; temples short, about 0.3 times as long as eyes, moderately projecting laterally (Figure 3A). Compound eyes at middle region of head approximately round in outline, distinctly convex and protruding laterally; neck region moderately constricted, slightly shorter than compound eyes. Gula sub-rectangular, narrowing anteriorly; gular suture reaching posterior margin of head, widely separating genal regions on ventral side (Figure 3B).
Head appendages: labrum not recognizable. Antennae inserted laterally, at about midlength between anterior margin of head capsule and anterior margin of eyes; scape slightly wider than long; pedicel shorter than scape; flagellum not preserved. Mandibles short, with fairly broad proximal part and with one apical tooth (Figure 3A). Ventral mouthparts not recognizable.
Pronotum: subparallel, slightly narrowing posteriorly; distinctly wider than head; about 2/3 as long as wide at anterior edge; about 3/5 times as long as width at posterior edge; anterior pronotal edge moderately concave; posterior edge straight; anterolateral edge rounded, moderately produced; posterior angles rounded; lateral margins almost straight, very slightly curved; lateral longitudinal line separating lateral projection from slightly convex main part of pronotum distinct; lateral projection (paranotum) slightly widened; central disc with two flat elevations (Figure 3A).
Scutellar shield: exposed, shield-like, distinctly longer than wide; lateral margins concave, slightly widening anteriorly.
Elytra: both elytra together about 2 times as wide as maximum width of prothorax; maximum width at elytral midlength; individual elytron 3.2 times as long as wide; very strongly pronounced dorsolateral ridges and sharply pronounced lateral edge enclose flat or even slightly concave epipleural rim; elytral disc enclosed by dorsolateral ridges, also flat or slightly concave except for anteriormost part; epipleural rim widening in anterior half, lacking distinct cells, narrowing towards apex; dorsolateral ridges anteriorly connected with elytral shoulders; main veins of elytra similar to intermediate ones (Figure 3A); elytral cells (=window punctures) moderately distinct, small; regular rows of large cells along lateral elytral margin absent (Figure 3C); elytra reaching slightly beyond abdominal apex; appearing dehiscent in posterior third (possibly an artifact of compression during fossilization).
Thoracic venter: prothoracic notopleural suture straight and diverging posteriorly; anapleural cleft converging posteriorly towards procoxae; both sutures enclose triangular, anteriorly narrowing pleura, which meet the anterior prothoracic margin at a narrow point; prosternal process absent; protrochantin not recognizable. Individual structures of mesoventrite not recognizable. Metaventrite trapezoidal, distinctly narrowing anteriorly; posterior margin 1.8 times as wide as length at midline; anterior margin distinctly narrower than posterior margin, about as wide as mesocoxae combined; mesocoxae separated by short, rounded median process of metaventrite; metathoracic discrimen and metakatepisternal suture present; metatrochantin present and exposed between hind margin of katepisternum and coxa. Individual structures of metapleuron not recognizable; metanepisternum apparently broad anteriorly and narrowing towards end of segment (Figure 3B).
Legs: procoxae medially adjacent, medium-sized, cone-shaped but rounded apically; protrochanter small, slightly oblong; profemora short, widening distally, with strongly convex posterior margin, distinctly thicker than proximally curved and slender protibiae and slightly longer; mesocoxae slightly smaller than procoxae, nearly circular; mesotrochanter nearly oblong; mesofemora short, not reaching lateral margin of elytra; parallel-sided, thicker than mesotibia and about equally long; metacoxae transverse, distinctly reaching beyond lateral margin of metaventrite; triangular, without metacoxal plates; posteromesal apices rounded, far from posterior margin of first visible abdominal ventrite; metatrochanter small, nearly triangular; metafemur short, not extending beyond lateral margins of body, proximally distinctly thicker than distally; metatibia longer than metafemur; curved proximally, subparallel, widening very slightly distally.
Abdomen: with five visible ventrites; narrowing towards apex from the base of ventrite 3; first ventrite longer than other ones; last ventrite (=sternite VII) 1.5 times as long as the previous one; hind margin evenly rounded (Figure 3B).
Dimensions (mm): body length 7.5, width 2.8, head length 1.1, width 1.2, anterior edge of pronotum 2.0, posterior edge of pronotum 1.5, pronotal width 1.1, elytral length 5.3, width 1.4.
Comments
Pareuryomma ancistrodonta sp. nov. clearly belongs to the genus Pareuryomma indicated by the following characteristics: pronotum widest anteriorly, narrowing posteriorly; epipleural space of elytron wide with 2 rows of cells in the proximal half and narrowing towards the apex. The new species differs from the type species P. tylodes in several features: temples shorter than the eyes, anterior pronotal angle rounded. It can distinguish from P. cardiobasis sp. nov. in the specific shape of the mandibles with a single apical tooth.
Pareuryomma cardiobasissp. nov.
Diagnosis
Mandibles stout, with a distinctly dilated and tridentate apical part; temples conspicuously projecting laterally, about as long as eyes; anterior margin of pronotum as long as posterior margin; pronotal hypomeron wide; central disc with cordiform elevation.
Etymology
Name derived from the Greek word ‘cardiobasis’, -is, -e, (heart-shaped), referring to the central disc of the pronotum with a large cordiform elevation.
Type material
Holotype: a well-preserved adult with body, elytra, legs and antennae. Registration No. CNU-C-LB2010809, housed in Key Lab of Insect Evolution & Environmental Change, Capital Normal University, Beijing, China.
Type locality and horizon
Near Chaomidian Village, Beipiao City, Liaoning Province, China, Yixian Formation (Early Cretaceous).
Description
Body small, flattened, densely covered with large tubercles (Figure 5B).
Head capsule: slightly shorter than maximum width at temples; upper surface more or less flattened, without raised tubercles or other prominent structures; anterior margin distinctly concave; frontoclypeal suture not recognizable (Figure 1A). Compound eyes at middle region of head largely integrated in the contour of the head, scarcely protruding laterally; neck region distinct narrow. Gula sub-rectangular; gular ridges reaching posterior margin of head, widely separating genal regions on ventral side (Figure 1B).
Head appendages: labrum not recognizable. Antennae inserted laterally; clavate, not reaching posterior margin of prothorax, distally widening; scape as long as last antennomere; pedicel wider than long, nearly as wide as scape; third antennomere not longer than second and fourth combined; antennomeres 7–10 short, distinctly broader than antennomeres 3–6; apical antennomere short and wide, appearing inflated. Labium with large submentum, slightly widening anteriorly, separated from gula by transverse suture; mentum not recognizable, apparently reduced; prementum large, plate-like; remaining elements of ventral mouthparts not visible (Figure 1A).
Pronotum: transverse, distinctly wider than head; widest at middle, slightly narrowing posteriorly; width at anterior margin about 1.5 times of length at midline; anterior pronotal edge along neck region almost straight, at most very slightly curved inwards, distinctly emarginated laterally, with rounded, moderately prominent anteriolateral edge; posterior angles completely rounded, not prominent; lateral longitudinal line separating lateral projection from slightly convex main part of pronotum moderately distinct; lateral pronotal projection (paranotum) distinctly widened; central disc bearing cordiform elevation (appearing as convexity in specimens with exposed ventral side) (Figure 1A).
Scutellar shield: exposed, triangular.
Elytra: disc flattened, only very slightly convex; both elytra together about 1.7 times as wide as maximum width of prothorax; individual elytron about 3 times as long as wide; maximum width at about midlength of elytra; pronounced dorsolateral ridges of elytra and sharply pronounced lateral edge enclosing flat or even slightly concave epipleural rim; elytral disc enclosed by dorsolateral ridges, also flat or slightly concave except for anterior-most part; dorsolateral ridges anteriorly connected with elytral shoulders; epipleural rim with two rows of cells in the proximal two thirds and one row in the distal third; main veins of elytra similar to intermediate ones; elytral cells (=window punctures) on disc small, indistinct; regular row of large cells along lateral margin absent; elytra reaching slightly beyond abdominal apex; appearing dehiscent in posterior third (possibly an artifact of fossilization) (Figure 1A).
Thoracic venter: prothoracic anapleural cleft converging posteriorly towards anterior procoxal margin; notopleural suture not visible; prosternal process absent. Mesoventrite with distinct discrimen; mesokatepisternal suture present as a distinct arched row of punctures. Metaventrite trapezoid, distinctly narrowing anteriorly; posterior margin 1.9 times as wide as length at midline; anterior margin slightly narrower than mesocoxae combined; mesocoxae separated by short, triangular, apically pointed process of metaventrite; metathoracic discrimen present but very short; metakatepisternal suture present; metatrochantins present and exposed between hind margin of katepisternum and coxa. Metanepisternum triangular, extensive, strongly widening anteriorly, and narrowing towards end of segment (Figure 1B).
Legs: procoxae nearly spherical, protruding, medially adjacent; protrochanter small, approximately triangular; profemora with convex anterior and posterior margins, distinctly widening in middle region, distinctly thicker than protibiae and slightly longer; protibia slender, slightly widening distally; two slender protarsomeres preserved; mesocoxae more conical, not protruding, posteriorly oriented, distinctly separated by mesokatepisternal region; mesotrochanter small, transverse; mesofemora with convex anterior and posterior margins, widening in middle region, distinctly thicker than mesotibia and slightly longer, not reaching beyond lateral margin of body; mesotibia subparallel, hind margin slightly convex; mesotarsus with 5 tarsomeres; tarsomeres 1 and 5 elongate, nearly equal in length; tarsomeres 2–4 distinctly shorter, only slightly longer than wide, nearly equal in length; metacoxae transverse, distinctly reaching beyond lateral margin of metaventrite; triangular, without metacoxal plates, posteromesal apices rounded, far from posterior margin of first visible abdominal ventrite; metatrochanter small, oblong; metafemur with very slightly convex anterior and posterior margin, short, not extending beyond lateral margin of body; metatibia very slightly widening distally, almost parallel-sided, shorter than metafemur; metatarsus 5-segmented; tarsomeres very similar to those of middle leg.
Abdomen: narrowing towards the apex from the base of ventrite 4; first abdominal ventrite longer than other ones, likely representing fused sternites II and III; last ventrite (=sternite VII) 1.35 times as long as previous one; hind margin evenly rounded.
Dimensions (mm): body length 6.6, width 2.5, head length 1.1, width 1.0, anterior edge of pronotum 1.5, posterior edge of pronotum 1.4, pronotal width 1.0, elytral length 4.5, width 1.4.
Comments
Pareuryomma cardiobasis sp. nov. differs from the type species in the following features: anterior margin of pronotum as long as the posterior margin, central pronotal disc bearing a cordiform elevation; from P. ancistrodonta in the presence of tridentate with perpendicular cutting edge of the mandible.
Genus Omma Newman, 1839
Omma Newman, 1839, Ann. Mag. Nat. Hist. 3:303; Peyerimhoff, 1902, Bull. Soc. Ent. Fr., p.330; Sharp and Muir, 1912, Trans. Ent. Soc. Lond., p. 521, 615, 632; Neboiss, 1959, Proc. Roy. Soc. Vic. 72:17; Crowson, 1962, Ann. Mag. Nat. Hist. 13(5): 147–157; Atkins, 1963, Can. Ent. 95: 140–162; Ponomarenko, 1964, Paleontol. Jour. 4: 45–55; Ponomarenko, 1966, Entomolog. Oboer. 1: 138–143; Ponomarenko, 1968 Nauka, Moscow. p. 118–138; Ponomarenko, 1969, Tru. Paleontol. Instit. A. N. SSSR, 125: 70–115; Ponomarenko, 1997, Paleontol. Jour. 31(4): 389–399; Lawrence, 1999, Inver. Taxon. 13:369–390; Ponomarenko, 2006, Paleontol. Jour. 40(1):90–99.
Type species
Omma stanleyi Newman, 1839; Recent.
Included species
Sixteen species have been described up to date. O. stanleyi Newman, 1839, O. mastersii Macleay, 1871, O. sagitta Neboiss, 1960 and O. rutherfordi Lawrence, 1999 are four extant species from Australia. The others are all fossil species from the Mesozoic of Siberia, Central Asia, Western Europe and China (shown in Table 1). In addition, O. delicata sp. nov. is described below.
Emended diagnosis
Body elongate, moderately flattened or almost cylindrical. Surface often tuberculate or rarely spinose. Head subquadrate to slightly elongate, always with distinct neck region; temples usually shorter than eye; antennal grooves absent. Antennae inserted laterally. Antennae filiform or somewhat moniliform, as long as or slightly shorter than head and prothorax together; antennomere 3 longest, as long as or longer than pedicel and antennomere 4 combined. Mandibles prominent, incurved. Labrum, clypeus, and frons fused. Pronotum subquadrate or slightly transverse, without lateral pronotal carinae; procoxal cavities contiguous. Legs moderately long and slender; tibiae usually not much longer than femora; mesofemora extending beyond side margins of body. Abdominal sternites arranged in one plane.
Note
The emended diagnosis is based on the type species and the new material.
Omma delicata sp. nov. (Figure 1)
Diagnosis
Body small; head distinctly wider posteriorly behind compound eyes. Scape subtriangular, 1.2 times longer than pedicel, thicker than other antennomeres. Pronotum square, anterior and posterior angles of pronotum completely rounded, not prominent. Elytra with indistinct veins and cells; elytra 1.8 times as wide as prothorax.
Etymology
Name derived from the Latin word ‘delicatus’, -a, -um (delicate), referring to the relatively small size of the new species.
Type Material
Holotype: nearly complete adult ommatid with body, elytra, part of legs and antennae. Registration No. CNU-C-LB2010813, housed in Key Lab of Insect Evolution & Environmental Change, Capital Normal University, Beijing, China.
Horizon and locality
Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China; Jiulongshan Formation, the Middle Jurassic (Bathonian- Callovian boundary).
Description
Body small, flattened, densely covered with tubercles (Figure 5C).
Head capsule: slightly longer than wide, but appearing elongated; distinctly narrower anteriorly than at ocular region; distinctly prognathous; without macroscopic tubercles on dorsal surface; anterior margin shallowly concave; temples distinctly shorter than eyes, moderately projecting laterally. Compound eyes posterior, approximately round in outline, distinctly convex and protruding laterally; neck region moderately constricted, with conspicuous postocular extensions (Figure 4A).
Head appendages: Antennae inserted laterally in front of eyes; filiform, thin, with 9 visible antennomeres; short, not reaching posterior margin of prothorax; scape subtriangular, longer than wide, wider apically than basally; pedicel thin, shorter than scape; antennomere 3 longer than others, nearly as long as pedicel and antennomere 4 combined; other antennomeres nearly equal in length, slightly widening distally; apical antennomere parallel-sided. Mandibles large, without recognizable teeth along horizontal mesal surface (Figure 4A). Remaining elements of ventral mouthparts not recognizable.
Pronotum: rounded at sides, widest posterior to midlength and not explanate, slightly wider than base of head; about 4/5 times as long as wide at anterior margin; posterior edge about as wide as pronotal length; anterior and posterior pronotal edges almost straight; central disc flattened, without elevation but with large tubercles (Figure 4A).
Scutellar shield: exposed, roughly triangular.
Elytra: maximum width at elytral midlength; individual elytron 3.7 times as long as wide; epipleural rim rather narrow; elytral disc enclosed by dorsolateral ridges, also flat or slightly concave except for anteriormost part; dorsolateral ridges anteriorly connected with elytral shoulders; elytra reaching slightly beyond abdominal apex; appearing dehiscent in posterior fourth (possibly an artifact of compression during the fossilization) (Figure 4A).
Thoracic venter: anapleural cleft converging posteriorly towards procoxae; prothoracic notopleural and sternopleural sutures enclose triangular, anteriorly narrowing pleura, which meet the notopleural suture at a narrow point; protrochantin not recognizable. Longitudinal suture (discrimen) present on mesoventrite. Metaventrite trapezoidal, distinctly narrowing anteriorly; posterior margin 2.1 times as wide as length at midline; anterior margin distinctly narrower than posterior margin, about as wide as mesocoxae combined; mesocoxae medially adjacent, separated by short, triangular, apically pointed process of metaventrite; metathoracic discrimen invisible; metakatepisternal suture present; metatrochantin present and exposed between hind margin of katepisternum and coxa (Figure 4B). Individual structures of metapleuron not recognizable; metanepisternum apparently broad anteriorly and narrowing towards end of segment.
Legs: procoxae nearly spherical, protruding, medially adjacent; protrochanter small, approximately triangular; profemur long, narrowing distally, with strongly convex posterior margin, distinctly thicker than protibia and slightly longer; protibia short, slender, slightly widening distally. Mesocoxae nearly triangular, larger than procoxae, medially adjacent; mesotrochanter small, longer than wide; mesofemora parallel-sided, with very distinct anterior and posterior margins, proximally wider than basally, distinctly thicker than mesotibia and equally long; mesotibia subparallel, with a short spur on the internal surface; mesotarsus with 4 visible tarsomeres; tarsomere 1 elongate, longer than others, tarsomeres 2–4 short. Metacoxae transverse, distinctly reaching beyond lateral margin of metaventrite, triangular, without metacoxal plates, posteromesal apices rounded, extending over mid-length of first visible abdominal ventrite; metatrochanter medium-sized, longer than wide; metafemora reaching beyond lateral margin of body; metatibia almost parallel-sided; metatarsi with 2 visible tarsomeres; tarsomere 1 elongate, longer than tarsomere 2.
Abdomen: narrowing towards apex from the base of ventrite 4; first ventrite longer than other ones; last ventrite (=sternite VII) 1.4 times as long as the previous one; apex rounded.
Dimensions (mm): body length 9.0, width 3.0, head length 1.5, width 1.6, anterior edge of pronotum 1.2, posterior edge of pronotum 1.7, pronotal width 1.5, elytral length 5.9, width 1.6.
Comments
The new species is similar to Omma antennatum Ponomarenko, 1997, O. avus Ponomarenko, 1969 and O. rutherfordi Lawrence, 1999 in the body size. It differs from O. avus Ponomarenko, 1969 by elytra almost completely lacking veins and cells, and the laterally projecting temples. It differs from O. antennatum Ponomarenko, 1997 in the following features: profemora not inflated anteriorly and posteriorly, pronotal angles completely rounded, not prominent; in contrast to O. rutherfordii Lawrence, 1999 the head behind the eyes is wide and not abruptly narrowed.
Tribe Tetraphalerini Crowson, 1962
Genus Tetraphalerus Waterhouse, 1901
Tetraphalerus Waterhouse, 1901, Ann. Mag. Nat. Hist. Ser 7, Vol. Vii:520–523; Heller, 1913, Wien. Ent. Zeit. 32: 235; Bruch, 1925, Physis. 7: 201–204; Monrós and Monrós, 1952, An. Soc. Cient. Argent. 154: 23–39; Crowson, 1962, Ann. Mag. Nat. Hist. 13(5): 147–157; Atkins, 1963, Can. Ent. 95: 140–162; Ponomarenko, 1964, Paleontol. Jour. 4: 45–55; Ponomarenko, 1966, Entomolog. Oboer. 1: 138–143; Ponomarenko, 1969, Tru. Paleontol. Instit. A. N. SSSR, 125: 70–115; Lin, 1976, Acta Palaeontol. Sin. 15(1): 97–115; Ponomarenko, 1986, Trans. Joint Soviet-Mongolia Paleon. Exped. 28, 84–107; Ponomarenko, 1993, Tru. Paleontol. Instit. A. N. SSSR, 252: 17–20; Ren et al., 1995, Seism. Pub. H. pp77-78; Ponomarenko, 1997, Paleontol. Jour. 31(4): 389–399; Ponomarenko, 2000, Acta Geolog. Hispan. 35, no1-2: 47–52; Sorinao and Delclòs, 2006, Acta Palaeontol. Pol. 51(1): 185–200; Tan, Ren and Shih, 2007, Ann. Zoo. (Warszawa), 57(2): 231–247.
Type species
Tetraphalerus wagneri Waterhouse, 1901; Recent.
Included species
25 species have been known before this study. T. wagneri Waterhouse, 1901 and T. bruchi Heller, 1913 are two extant species from South America. The others are all fossil species from the Mesozoic of Siberia, Central Asia, Western Europe, Western Australia and China. In addition, T. decorosus sp. nov. is described below.
Emended diagnosis
Head narrow anteriorly and broad in post-ocular region, with ridges and lobes. Antennae filiform or somewhat moniliform, as long as or slightly shorter than head and prothorax taken together; longitudinal, distinct antennal groove present on ventral side of head; antennomere 3 slightly long than antennomere 4. Clypeus and frons fused; labrum short, transverse. Mandibles prominent, incurved; temples as long as or longer than eyes. Pronotum nearly rectangular, as wide as head or narrower, with lateral longitudinal line; central part of pronotum strongly raised; procoxal cavities contiguous. Elytra 1.5 times to twice as wide as prothorax. Legs short, mesofemora not extending well beyond side margins of body; tarsal segment 4 simple. Abdominal sternites arranged in one plane, abutting, not overlapping.
Note
The emended diagnosis is based on the type species and the new material.
Tetraphalerus decorosussp. nov.
Diagnosis
Head slightly longer than wide; antennae moniliform; antennomeres 5–10 short, distinctly broader than antennomeres 3–4, distally widening; apical antennomere appearing inflated. Maximum width of elytra posterior to midlength; abdominal ventrites narrowing towards apex from the base of ventrite 3; first abdominal ventrite longer than the other ones; last ventrite (=sternite VII) 1.3 times as long as the previous one; hind margin evenly rounded.
Etymology
Name derived from the Latin word ‘decorosus’, -a, -um, referring to the new species preserved completely.
Type Material
Holotype: a nearly complete adult with body, elytra, and parts of legs and antennae. Registration No. CNU-C-LB2010812, housed in Key Lab of Insect Evolution & Environmental Change, Capital Normal University, Beijing, China.
Horizon and locality
Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China; Jiulongshan Formation, the Middle Jurassic (Bathonian- Callovian boundary).
Description
Body small, surface densely covered with large tubercles (Figure 5D).
Head capsule: with distinctly protruding compound eyes at middle region of head approximately semicircular in outline, slightly wider than long; distinctly narrower anteriorly and posteriorly than at ocular region and temples; distinctly prognathous; anterior clypeal margin straight; frontoclypeal transverse line not recognizable; temples distinctly shorter than eyes, moderately projecting laterally. Ocelli absent. Two distinct circular, flat macro-tubercles present between posterior margins of eyes; median epicranial suture indistinctly visible; neck region distinctly constricted, as long as compound eyes (Figure 2A). Antennal groove on ventral side of head not visible.
Head appendages: Antennae inserted laterally in front of the eyes; moniliform, short, not reaching posterior margin of prothorax, wider apically than basally; scape approximately triangular, widening distally; pedicel small; antennomere 3 as long as pedicel and antennomere 4 combined. Mandibles exceptionally long and distinctly protruding; without recognizable tooth along horizontal mesal surface; outer margin curved; neck region moderately constricted, approximately as long as compound eyes (Figure 2A). Two maxillary palpomeres visible; remaining elements of ventral mouthparts not recognizable.
Pronotum: transverse, slightly wider than head; about 1.1 times as wide as anterior edge; about 1.3 times as wide as posterior edge; anterior and posterior margin almost straight; anterior and posterior angles of pronotum not prominent; lateral margin moderately serrate and moderately explanate; prothoracic hypomeron narrow; central disc near lateral pronotal carinae bearing two oblong flat convexities (Figure 2A).
Scutellar shield: exposed, shield-like, distinctly longer than wide; lateral margins concave, slightly widening anteriorly.
Elytra: individual elytron about 3.2 times as long as wide; pronounced dorsolateral ridges and sharply pronounced lateral edge enclose flat or even slightly concave epipleural rim; elytral disc enclosed by dorsolateral ridges, also flat or slightly concave except for anteriormost part; epipleural rim slightly widening in anterior 1/3, bearing one row of cells, narrowing towards apex; dorsolateral ridges anteriorly connected with elytral shoulders (Figure 2A); longitudinal ridges with small tubercles, with 9 rows of cells; elytral cells (=window punctures) moderately distinct, small, polygonal, with 4 black maculae on their margins; about 28 cells arranged in a row; regular rows of large cells along lateral elytral margin absent (Figure 2C); elytra reaching slightly beyond abdominal apex; appearing dehiscent in posterior third (possibly an artifact of compression during fossilization).
Thoracic venter: Individual structures of meso- and metaventrites not recognizable; metakatepisternal suture present; metatrochantins present and exposed between hind margin of katepisternum and coxa (Figure 2B).
Legs: procoxae medially adjacent, medium-sized, cone-shaped but rounded apically; protrochanter medium sized, longer than wide; profemur long, with strongly convex posterior margin; distinctly thicker than proximally curved and slender protibia and slightly longer; protibia short, slightly widening distally; protarsus 5-segmented; tarsomeres 2–4 short, only slightly wider than long; tarsomere 5 longer than others, with one claw; mesocoxae inconspicuous, slightly smaller than procoxae, apparently globular in outline, separated from each other; metacoxae transverse, triangular; without metacoxal plates; posteromesal apices rounded, far from posterior margin of first abdominal ventrite (Figure 2B).
Abdomen: narrowing towards apex from the base of ventrite 3; hind margin evenly rounded (Figure 2B).
Dimensions (mm): body length 8.7, width 3.1, head length 1.6, width 1.4, anterior edge of pronotum 1.6, posterior edge of pronotum 2.0, pronotal width 1.5, elytral length 5.5, width 1.7.
Comments
The new fossil specimen is assigned to Tetraphalerus based on the following suite of characters: head nearly as wide as pronotum, antennae short, third antennomere longer than fourth, and the pronotum with lateral pronotal carinae. The presence of two prominences on the vertex suggests a placement of the new species to the T. bruchi series. The new species is distinctly different from other species in several features: head wider than long; antennae moniliform.
Phylogenetic results
-
(a)
Tree for fossil and extant Ommatidae
Nine most maximum parsimonious trees were obtained in the NONA analysis (tree length = 57 steps, CI = 0.50, RI = 0.80). A similar result was obtained in analyses using TNT (9 trees, 57 steps). The strict consensus tree obtained with NONA with Bremer support values mapped on branches is shown in Figure 6. The cladistic result obtained by TNT is similar to the results by NONA (see Additional file 2). The constrained analysis forcing the monophyly of Tetraphalerus + Odontomma and Pareuryomma + Notocupes yielded 434 most-parsimonious trees (tree length = 67 steps, CI = 0.42, RI = 0.76; see Additional file 3: Figure S1B), with 10 additional steps compared to the unconstrained results. The constrained analysis forcing the monophyly of Tetraphalerus and Odontomma yielded 972 most-parsimonious trees (tree length = 61 steps, CI = 0.48, RI = 0.80; see Additional file 3: Figure S1C). The constrained analysis forcing the monophyly of Pareuryomma + Notocupes yielded 140 most-parsimonious trees (tree length = 63 steps, CI = 0.46, RI = 0.79; see Additional file 3: Figure S1D)
The constrained analysis forcing the monophyly of Tetraphalerus + Odontomma and Pareuryomma + Notocupes yielded 434 most-parsimonious trees (tree length = 67 steps, CI = 0.42, RI = 0.76; see Additional file 3: Figure S1), which need nine additional steps more than the most parsimonious results. The constrained analysis forcing the monophyly of Tetraphalerus and Odontomma yielded 972 most-parsimonious trees (tree length = 61 steps, CI = 0.48, RI = 0.80; see Additional file 3: Figure S1). The constrained analysis forcing the monophyly of Pareuryomma + Notocupes yielded 140 most-parsimonious trees (tree length = 63 steps, CI = 0.46, RI = 0.79; see Additional file 3: Figure S1).
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(b)
Apomorphies of selected clades
The monophyly of Ommatidae is supported by two apomorphic characters: the antenna not reaching hind margin of prothorax posteriorly (ch. 9), and the medially adjacent procoxae (ch. 18). In all trees, Notocupoides and Eurydictyon are a monophyletic group (sharing ch. 27) and form the sister group of all other included ommatid taxa. Ommatidae excl. Notocupoides + Eurydictyon is supported by a ratio labral width/clypeal width less than 1 (ch. 7:1).
Ommatidae excluding the traditional tribe Notocupedini (including the genera Notocupoides, Eurydictyon, Notocupes, Amblomma, Rhabdocupes, and Zygadenia) are monophyletic. This clade is supported by the absence of a longitudinal bulge or keel on the dorsal head surface (ch. 0:1), the distinct elongation of the third antennomere (ch. 11:1), and the small size of the window punctures on the elytron (ch. 25:1).
A clade including the genera Brochocoleus, Odontomma, Pareuryomma, Liassocupes, Omma, Cionocoleus, Tetraphalerus and Tetraphalerites is suggested by abutting abdominal sterna (ch. 20:0). However, this condition is arguably plesiomorphic. Lithocupes, the only single genus of the tribe Lithocupedini, is placed as the sister taxon of this clade in all trees, shared derived features are the above mentioned apomorphies of Ommatidae excl. the traditional Notocupedini.
The three genera Brochocoleus, Odontomma and Pareuryomma constitute a clade defined by one non-homoplasious character, an epipleural rim containing more than one row of cells near its basal part (ch. 23:1), and one homoplasious character, the absence of the posteromesal dorsal protuberance of the head (ch. 1:1). Liassocupes, Omma and Cionocoleus are supported as a clade by the absence of the median epicranial (=coronal) suture on the dorsal head (ch. 2:1). The two genera, Tetraphalerus and Tetraphalerites share a non-homoplasious apomorphic character state, the presence of ventrolateral antennal grooves (ch. 3:1). However, this ventral groove is not visible in the fossils of Tetraphalerus. There are several homoplasious characters also supporting this group, such as a strongly transverse labrum (as wide as the clypeus) (ch. 7:0) and a mesofemur not extending beyond side margins of body (ch. 21:1). The two lineages are likely sister taxa, as suggested by the non-homoplasious absence of the frontoclypeal suture (ch. 6:1), which reduced countless times in Coleoptera, and the narrower lateral pronotal projection (ventrally corresponding with pronotal epipleura) (ch. 17:1).