Decomposita, Vršanský, 2008

Vršanský, Peter, 2008, Central ocellus of extinct cockroaches (Blattida: Caloblattinidae), Zootaxa 1958, pp. 41-50 : 42-47

Decomposita gen. nov.

Type species. Decomposita triocella sp. nov.

Differential diagnosis. The genus (and also remaining two herein described genera) can be cathegorised within the order Blattida (= Blattaria = Blattodea ) basing on general habitus, pronotum with distinct paranotalia and carinated legs. Synapomorphies with the Blattida are morphology of hypognathous head, and characteristic venation pattern of forewings (short Sc and pectinated regulary branched veins, and with distinct clavus) and hindwings (simple Sc; R1 and RS differentiated, simplified M and branched CuA, simple CuP).

It can be further determined as belonging to the Caloblattinidae basing on the characteristic venation with distinct intercalaries, and forewing with sparsely branched Sc.

Decomposita differs from all representatives of the family in having pronotum very small, only partly overlying head, by free forelegs with long coxae, and by soft and fragile large forewings with narrow costal space.

Its closest relatives are placed in the cosmopolitan Mesozoic genus Rhipidoblattina (polyphyletic, heterogeneric group under revision), namely Rhipidoblattina hebeiensis Hong, 1980 from the Middle Jurassic of Luanping, China which possessed identical coloration, but which is autapomorphic in having terminally dichotomised medial branches of CuA.

Related taxa are R. karatavica Vishniakova, 1968 from the Upper Jurassic Karabastau Formation in Kazakhstan, which is slightly larger (forewing length up to 21.5 mm), with round pronotum (apomorphy – ancestral Phyloblattidae and stem Caloblattinidae have pronotum transversal); narrow head (apomorphy – head is wide in ancestral taxa) and more curved forewing R within wider R area (plesiomorphy); and the much older R. angustata Martynov, 1937 from the Lower Jurassic strata of Shurab in Tajikistan, which is smaller (about 12mm) ( Caloblattinidae are large, thus this character is a strong apomorphy) and has wider radial area (plesiomorphy). Synapomorphies include forewing elongation with almost parallel wing margins.

Another related taxon is Subioblatta tongchuanensis Lin, 1978 from the Upper Triassic Yenchang Formation of Hejiagon in Tongchuan of Shensi, China, which possesses an identical coloration and venation pattern similar to R. karatavica , but was smaller (11mm) with long Sc terminally branched (5) and reduced veins.

Related is also Rhipidoblattina emacerata Zhang, 1986 from the Jurassic or Cretaceous of Northern Hebei in China, but Decomposita triocella sp. nov. has more simplified venation (apomorphy). R. fuxinensis Lin, 1976 and R. decoris Lin, 1978 from the Jurassic or Cretaceous of Yixian, China, R. lanceolata Hong, 1980 and R. longa Hong, 1980 from the Middle Jurassic of Chendge, China attributed to the same genus, generally more closely resemble Liadoblattina Handlirsch, 1906 (wider forewing with dense venation) and might belong to the Raphidiomiomidae – thus are not directly related to the present taxon. R. laterniforma Lin, 1978 possesses a unique pronotum (with a narrow apical part and wide distal part) and more sophisticated coloration. This taxon probably represents a separate genus. R. geikei (Scudder, 1886) from the Early Jurassic sediments from England is smaller (~ 14 mm), with plesiomorphic, rich venation and wing margins less parallel.

Description. Head more or less globular, with tree distinct concave ocelli, and slender antennae. Pronotum small, nearly globular, slightly longitudinal.

Forewing thin, soft and fragile, with narrow costal field, simple or 2-branched Sc, simple R branches; M branches long and straight, CuA expanded, with the anteriormost branch straight and simple.

Hindwing with simple Sc, R, and Rs differentiated; M expanded.

Legs long and thin, with free coxae.

Discussion. The narrow costal field and free forelegs with carination of femur in two rows along a longitudinal ridge, allowing catch of food, and a small, narrow pronotum are synapomorphic with the Raphidiomimidae , which might suggest the ancestral, in respect to Raphidiomimidae , position of the Decomposita .

Etymology. From Latin compositus – aggregated, made up of parts, and de – antonymous prefix in Latin. Gender: feminine.

Decomposita triocella sp. nov.

(Figs 1,2,5)

Differential diagnosis. As for genus.

Description. Head globular, eyes large, three ocelli large. Lateral ocelli are closely approximated while the central ocellus is placed nearly among antennal foramens. Narrow mandibles possess very sharp and large teeth. Pronotum nearly globular, coloured (Figs 1,2,5). Legs long and robust, the fore femora free, with very long coxa; tibia heavily carinated.

Forewings large; length/width ca. 15/ 5 mm. Costal space narrow, pale; Sc simple or with 2 branches. 12–13 R branches simple. Four M branches long. CuA expanded, with 7 branches, anterior branches long and straight. A branched, with 8( RF)–11(LF) veins at margin. Coloration as in Figs. 1, 5.

Hindwing with simple Sc, R 4, Rs 5; M 6+.

Etymology. From Greek treis – three and Latin ocellus – diminitive from oculus.

Holotype. PIN 2554 /36. Complete specimen.

Additional material. PIN 2066/ 367; 2554/30. Forewing with pronota.

Type locality. Karatau, Kazakhstan.

Type horizon. Karabastau Formation, Oxfordian or Kimmeridgian (Upper Jurassic).

Discussion. Specimens PIN 2066/ 367; 2554/30 are housed within this taxon basing on the identical size and forewing coloration pattern.

Apparently legs could be used for catching food, and the sharp mandibles may suggest carnivory. Wings were thin and fragile - they are cracked and folded, unlike any of the thousands of preserved Mesozoic cockroaches.

Character of preservation: 3 complete specimens (two without head).

Srdiecko gen. nov.

Type species. Srdiecko tri sp. nov.

Differential diagnosis. Srdiecko differs from all the known representatives of the family by the extremely robust head, as wide as long (half as high) and, except for Rhipidoblatta Vishniakova, 1968 and Solemnia Vršanský, 2008a , by comparatively narrow wings. The new genus can be attributed within the Caloblattinidae basing on the hindwing venation and multisegmented cerci. The large size, short head, cord-like pronotum, narrow hindwing and body are also synapomorphic with the sister genus Rhipidoblatta .

During the Karatau time (Oxfordian or Kimmeridgian), diverse shape of the pronotum and head are represented among Caloblattinidae , unlike in the Middle Jurassic, when the representatives of the family were rather uniform. This indicates derived life forms of the Caloblattinidae originated during the late Middle or the Late Jurassic. Unfortunatelly, the Upper Jurassic sediments are mostly restricted to the Eurasia, thus the paleozoogeographic relations are hardly to consider.

Description. Head robust, wide, almost globular, with short palp and large antennal foramens. Ocelli located nearly linearly. Clypeus very large, mandibles robust, with two teeth. Pronotum cordiform, of subequal length and width. Hindwing with narrow remigium. Sc simple, differentiated Rs, and expanded media, coloured apically and in radial area.

Etymology. From Slavic srdce – heart, alluded to the shape of the pronotum. Gender: neuter.

Srdiecko tri sp. nov.

(Figs 3,6)

Differential diagnosis. As for genus.

Description. Head robust, almost as long as wide (5.8mm), coloured, with pale triangle in the base of head. Antennal foramens are very large (diameter 1.0mm), antennal basalmost segments very wide. Three ocelli, probably not extending over the head surface, large (0.45mm), placed nearly linearly, the central ocellus slightly apically. Mandible is with fine teeth, palpae fine and short (significantly shorter than head). Eyes are narrow and very long.

Pronotum cordiform (length/width 7.4/ 8.3mm), with distal coloration as in figs.3,6. Body comparatively narrow, with long, multisegmented cerci. Hindwing (length ca. 18mm) coloured in the apical and radial area.

Etymology. The specific epithed is derived from Greek treis, and Slavic tri – three – alluding to the presence of three ocelli.

Holotype. PIN 1789 /39. Head, pronotum, body with ovipositor and a fragment of a hindwing.

Character of preservation. Single complete specimen.

Type locality. Karatau, Kazakhstan.

Type horizon. Karabastau Formation, Oxfordian or Kimmeridgian (Upper Jurassic).

Discussion. The head is preserved almost lateraly (figs.3,6). In the living position, the width perhaps approaches the length. In the Caloblattinidae , heads are represented by extremely diverse forms: classical hypognathous in most species such as in Decomposita triocella , very wide such as in the present species, but also almost prognathous such as in Paleovia praecarnia sp.n.

Paleovia gen. nov.

Type species. Paleovia precarnia sp. nov.

Differential diagnosis. Differing from all represetatives of the family in prognathous head and general monochromatic dark coloration, and by three small ocelli forming an isosceles triangle. Forewing with Sc regularly branched, with ca. 3 branches. Most radial branches simple; M reduced to some 6 straight veins. Paleovia represents a sister taxon to the complex Rhipidoblatta Vishniakova, 1968 + Srdiecko gen. nov., synapomorphic with Rhipidoblatta (characters unknown in Srdiecko , but perhaps also present) in identical shape and morphology of the forewing, and, possibly by the shape of the pronotum

Etymology. The genus name is derived from palaeo and via from Latin path. Gender: feminine.

Discussion. The complex of three closely related genera, namely Decomposita gen. nov., Srdiecko gen. nov. and Paleovia gen. nov., indigenous to the locality, indicates the phyllogeny of the otherwise uniform group was rapid.

The strong foreleg carination and the prognathous head are synapomorphies with the predatory Raphidiomimidae as a possible predatory adaptation, but the forewings are without narrow costal field (plesiomorphy) and the mandibular teeth are slender, which may exclude the possibility of this taxon being carnivorous.

Prognathous head and uniformly coloured body, head, pronotum and wings are strong autapomorphies.

Paleovia praecarnia sp. nov.

( Figs 4, 7)

Differential diagnosis. As for genus.

Description. Head long and narrow, length/width 3.7/ 2.3 mm. Eyes are long and narrow, narrow clypeus and coloration in area of ocelli, which form isosceles triangle, pale. Antennal pits are comparatively small, antennae filiform with short and broad segments. Labial palps ca. 4mm long, the terminal segment is very short (0.5mm). Pronotum round, dark. Forewing length ca. 20.5 mm. Sc with 4 veins; R with 14 veins at the margin, M with 6 long and straight veins, CuA expanded, with 8 or more veins. Legs robust, with strong and long spurs.

Etymology. The specific epithet is derived from prae, Latin preffics for before, and carnia from carnivore.

Holotype. PIN 2554 /33. Head, pronotum, fore legs, and a fragment of a forewing.

Type locality. Karatau, Kazakhstan.

Type horizon. Karabastau Formation, Oxfordian or Kimmeridgian (Upper Jurassic).