Diplorrhina
Diplorrhina Hawle and Corda is a genus of trilobite belonging to Order Agnostida. It lived during the early Middle Cambrian in what are now the Czech Republic and the North Siberian plateau. as in members of the family Peronopsidae it lacks a preglabellar furrow. Both cephalon and pygidium lack spines. It is difficult to distinguish Diplorrhina from many other peronopsids.
Taxonomy
The ancestor of Diplorrhina is most likely one of the Siberian species of the genus Archaeagnostus. D. recta is the most primitive species and it gave rise to D. cuneifera, which was in turn ancestral to Diplorrhina triplicata.
Species previously assigned to ''Diplorrhina''
D. normata = Peronopsis (Proacadagnostus) normataD. spitiensis = Peronopsis (Svenax) spitiensis
Distribution
D. triplicata is known from the early Middle Cambrian of the Czech Republic.D. cuneifera has been collected from the early Middle Cambrian of the Czech Republic D. redita occurs in the early Middle Cambrian of the Czech Republic. Agnostus cambrensis Harkness & Hicks was identified by Lake as Agnostus integer Beyrich , but re-examination of this specimen shows it to be referable to Diplorrhina redita. The species was placed in Peronopsis by Rees et al.,. From upper part of the Whitesands Bay Formation, lower T. fissus Biozone.D. recta was recovered from the early Middle Cambrian of Eastern Siberia.D. lata is found in the Middle Cambrian of Eastern Siberia.
Description
Both border and border furrow of the cephalon are relatively narrow. The transglabellar furrow is straight or curved slightly towards posterior. The posterior glabellar lobe is parallel sided, has two pairs of lateral furrows and small basal lobes; there is no median node. The pygidial border is flattened and wide with posterolateral angles, but no spines. The pygidal lobes reach the median node but do not cross the axis. The distance between the pygidial axis and border furrow is short or sometimes touching.
Differences with ''Peronopis''
Diplorrhina differs from members of the subgenus Peronopsis in the better developed transaxial furrows, better developed lateral furrows of the glabella, larger basal lobes, and in the trend towards the formation of a transverse depression of the axis.