Transitional fossil earwigs - a missing link in Dermaptera evolution

<p>Abstract</p> <p>Background</p> <p>The Dermaptera belongs to a group of winged insects of uncertain relationship within Polyneoptera, which has expanded anal region and adds numerous anal veins in the hind wing. Evolutional history and origin of Dermaptera have been in contention.</p> <p>Results</p> <p>In this paper, we report two new fossil earwigs in a new family of Bellodermatidae fam. nov. The fossils were collected from the Jiulongshan Formation (Middle Jurassic) in Inner Mongolia, northeast China. This new family, characterized by an unexpected combination of primitive and derived characters, is bridging the missing link between suborders of Archidermaptera and Eodermaptera. Phylogenetic analyses support the new family to be a new clade at the base of previously defined Eodermaptera and to be a stem group of (Eodermaptera+Neodermaptera).</p> <p>Conclusion</p> <p>Evolutional history and origin of Dermaptera have been in contention, with dramatically different viewpoints by contemporary authors. It is suggested that the oldest Dermaptera might possibly be traced back to the Late Triassic-Early Jurassic and they had divided into Archidermaptera and (Eodermaptera+Neodermaptera) in the Middle Jurassic.</p

New Transitional Fleas from China Highlighting Diversity of Early Cretaceous Ectoparasitic Insects

SummaryFleas are a group of highly specialized blood-feeding ectoparasites whose early evolutionary history is poorly known [1, 2]. Although several recent discoveries have shed new light on the origin of the group [3, 4], a considerable gap exists between stem fleas and crown fleas. Here we report a new transitional flea, Saurophthirus exquisitus sp. nov., assigned to a new family Saurophthiridae fam. nov., from the Lower Cretaceous Yixian Formation of northeastern China. Saurophthirids are more similar to crown fleas than other stem fleas in having a relatively small body size, relatively short and slender piercing-sucking stylet mouthparts, comparably short and compact antennae, rows of short and stiff bristles on the thorax, and highly elongated legs. The new finding greatly improves our understanding of the morphological transition to the highly specialized body plan of extant fleas. However, saurophthirids also display several features unknown in other fleas, and some of these features are suggestive of a possible ectoparasitic relationship to contemporaneous pterosaurs, though other possibilities exist. The new fossils, in conjunction with previous discoveries, highlight a broad diversity of ectoparasitic insects in the mid-Mesozoic

Jurassic scorpionflies (Mecoptera) with swollen first metatarsal segments suggesting sexual dimorphism

Background: Sexual dimorphism is widespread in insects. The certain specialized structures may be used as weapons in male–male combats or as ornaments to enhance mating opportunities. Results: We report striking swollen first tarsal segments in two families, four genera and six species of scorpionflies from the Middle Jurassic Yanliao Biota of Northeastern China. Swollen tarsal segments are restricted to male specimens and to hind leg tarsi. The geometric morphometric analyses reveal that the degree of swelling within the orthophlebiid species possessing swollen first metatarsal segments is species-specific, which can be used as a diagnostic character for taxonomic and phylogenetic studies. Conclusions: The new findings indicate that swollen first metatarsal segments are relatively common in the family Orthophlebiidae during the Middle Jurassic. The tarsal swellings are considered to be sexually dimorphic, potentially associated with sexually display by males and/or camouflage of a “nuptial gift” in the mating process

A golden orb-weaver spider (Araneae: Nephilidae: Nephila) from the Middle Jurassic of China

Nephila are large, conspicuous weavers of orb webs composed of golden silk, in tropical and subtropical regions. Nephilids have a sparse fossil record, the oldest described hitherto being Cretaraneus vilaltae from the Cretaceous of Spain. Five species from Neogene Dominican amber and one from the Eocene of Florissant, CO, USA, have been referred to the extant genus Nephila. Here, we report the largest known fossil spider, Nephila jurassica sp. nov., from Middle Jurassic (approx. 165 Ma) strata of Daohugou, Inner Mongolia, China. The new species extends the fossil record of the family by approximately 35 Ma and of the genus Nephila by approximately 130 Ma, making it the longest ranging spider genus known. Nephilidae originated somewhere on Pangaea, possibly the North China block, followed by dispersal almost worldwide before the break-up of the supercontinent later in the Mesozoic. The find suggests that the palaeoclimate was warm and humid at this time. This giant fossil orb-weaver provides evidence of predation on medium to large insects, well known from the Daohugou beds, and would have played an important role in the evolution of these insects

Priacma renaria Tan, Ren & Shih, 2006, sp. nov.

&lt;i&gt;Priacma renaria&lt;/i&gt; sp. nov. &lt;p&gt;(Figs. 4, 19&ndash;23, 25)&lt;/p&gt; &lt;p&gt; &lt;b&gt;Diagnosis.&lt;/b&gt; Differs from &lt;i&gt;P. serrata&lt;/i&gt; in the absence of spines on edge of elytra. From &lt;i&gt;P. corrupta&lt;/i&gt; in the mesosternum of new species without cross suture, from &lt;i&gt;P. longicapitis&lt;/i&gt; and &lt;i&gt;P. oculata&lt;/i&gt; in the ventral head surface of new one without grooves for inserting antennae, from &lt;i&gt;P. striata&lt;/i&gt; in the elytron of new one without paler flecks, from &lt;i&gt;P. sanzii&lt;/i&gt; in new one&rsquo;s antennal second segment shorter than third segment. &lt;i&gt;P. renaria&lt;/i&gt; &lt;b&gt;sp. nov.&lt;/b&gt; is distinct from other new species described here by being largest, by having elytral cells polygonal without black macula on their margins, and by the presence of about 43 elytral cells in a row.&lt;/p&gt; &lt;p&gt; &lt;b&gt;Description.&lt;/b&gt; Body length 19.5 mm, body width 5.0 mm, elytron length 14.0 mm. Large&shy;sized and subcylindrical beetle, covered with tubercles (Fig. 4).&lt;/p&gt; &lt;p&gt;Head wider than long, trapeziform, bearing two pairs of tubercles, anterior pair of tubercles at base of antennae, conical, small, shape of posterior ones like kidney&shy;form, larger than anterior pair; eyes medium&shy;sized; mandibles prominent, broad, flattened, shorter than half width of head, tridentate in horizontal cutting surface (Fig. 22), cervical constriction distinct.&lt;/p&gt; &lt;p&gt;Antennae filiform, incomplete (with 9 visible segments), scape shortest, thicker than other segments, pedicel 0.85 times as long as third antennomere (Figs. 19, 22), following segments homonomous.&lt;/p&gt; &lt;p&gt;Pronotum transverse, slightly wider than head, narrowed towards base, about 0.85 times as wide as long at posterior edge, anterior margin straight, anterior angles oblique (Figs. 19, 22), without propleuron, disc of pronotum bearing 2 oblong elevations; scutellum sub&shy;triangular.&lt;/p&gt; &lt;p&gt;Elytra about 2 times as wide as prothorax, 4.4 times as long as wide, epipleural rim narrow, with 10 rows of cells, elytral cells quadrangular, without black macula on their margins (Figs. 21, 25), approximately 43 cells formed in a row.&lt;/p&gt; &lt;p&gt;Ventral surface (Fig. 20) with gula rectangular, reaching posterior ridge of the head, widening posteriorly, genae widely separated ventrally. Procoxal cavities separated, prosternal process extending beyond coxae. Metaventrite trapezoidal, transverse, 0.7 times as wide as long (at posterior margin), without longitudinal suture on metaventrite (Fig. 23). Abdomen with 5 visible ventrites superimposing each other, narrowed from the base of fifth visible ventrite, first visible abdomen ventrite longest, 2&ndash;4 visible abdomen ventrites equal in length, last visible ventrite 2.2 times as long as the previous one, its apex tapered.&lt;/p&gt; &lt;p&gt;Legs with procoxae rounded, small, protrochanter triangular, profemora long, thick, protibiae comparatively slim, shorter than profemora; mesocoxae oblong, mesotrochanter small, circular, mesotibiae as long as mesofemora; metafemora short, metatibiae longer than metafemora, metatarsi with 5 segments, fifth segment longest, following segments homonomous (Fig. 20).&lt;/p&gt; &lt;p&gt; &lt;b&gt;Holotype.&lt;/b&gt; Nearly complete adult, No. CNU &ndash;C&ndash;LB2006002, housed in the Key Lab of Insect Evolution &amp; Environment Change, College of Life Science, Capital Normal University, Beijing, China.&lt;/p&gt; &lt;p&gt; &lt;b&gt;Locality and horizon.&lt;/b&gt; Collected near Chaomidian Village, Beipiao City, Liaoning Province, China; the Yixian Formation, Late Jurassic&shy;Early Cretaceous (Late Tithonian to the Berriasian).&lt;/p&gt; &lt;p&gt; &lt;b&gt;Etymology.&lt;/b&gt; The specific epithet derives from the Latin adjective &lt;i&gt;renarius&lt;/i&gt;, &shy; &lt;i&gt;a&lt;/i&gt;, &shy; &lt;i&gt;um&lt;/i&gt; (of or belonging to kidneys). It refers to the kidney&shy;shaped tubercles on the head.&lt;/p&gt;Published as part of &lt;i&gt;Tan, Jingjing, Ren, Dong &amp; Shih, Chungkun, 2006, First record of fossil Priacma (Coleoptera: Archostemata: Cupedidae) from the Jehol Biota of western Liaoning, China, pp. 55-68 in Zootaxa 1326&lt;/i&gt; on pages 65-67, DOI: &lt;a href="http://zenodo.org/record/174106"&gt;10.5281/zenodo.174106&lt;/a&gt