Echinopla species groups

The following species groups are based on morphological characters and were published by Xu and Zhou (2015). Zettel and Laciny (2017) added a few new groups and modified the diagnostic details of others to account for new species they described in 2017. A few more species have been described since then and were assigned to existing species groups. The treatments below include information from Echniopla taxonomic studies through to Laciny et al. 2019.

Identification
There is no single key to all the Echnopla species. There is a worker Key to Echinopla species that includes ~2/3 of the species and a key to a subset of the E. serrata group species (see the serrata group treatment below).

Echinopla melanarctos group

 * Echinopla cherapunjiensis
 * Echinopla circulus
 * Echinopla melanarctos
 * Echinopla pallipes
 * Echinopla tritschleri

Eyes located behind midlength of head. Frontal lobes broad, lateral margin nearly straight or sinuate, completely or partially concealing antennal fossae (Figs. 27-30). Mesosoma dorsum strongly convex, complete or interrupted by impressed metanotal groove (Figs. 31-34). Mesosoma usually constricted at metanotal groove. Petiole transverse, sides and upper margin spined and toothed. Dorsa of head and mesosoma abundantly bluntly spined with background retirugose; gaster abundantly bluntly spined, longitudinally striate or densely cribrate. Body surface with abundant hairs and pubescence.

Echinopla mezgeri group

 * Echinopla jeenthongi
 * Echinopla mezgeri
 * Echinopla tunkuabduljalilii

Head longer than wide; eyes positioned at its mid-length. Antennal fossae largely covered by frontal carinae. Mesosoma elongated, with weakly impressed mesometanotal suture; pronotum with tooth-like protrusions. Petiolar node subtriangular in lateral view, without spines or teeth. Gaster tergite 1 with ventrally curved posterior margin, covering the following gastral segments dorsally. Body surface dull black, with extremely fine sculpture, almost without standing setae.

Borneo, Peninsular Malaysia, Java.

Laciny et al. (2019) report there is an undescribed species from Java that is a member of this group (Seiki Yamane, pers. comm. to HZ).

Echinopla mistura group

 * Echinopla mistura

Eyes located at midlength of head. Frontal lobes very narrow and suberect, antennal fossae exposed. Mesosoma dorsum straight and entire, without suture and groove. Petiole cubic, without spines and teeth. Body surface shagreen, without strong sculptures. Body dorsum hairless.

The lone species in this group occurs in the Mollucas.

Echinopla nitida group

 * Echinopla nitida

Eyes located behind midlength of head. Frontal lobes broad, roundly laterally convex and concealing antennal fossae. Mesosoma dorsum weakly convex and entire, without suture and groove. Petiole transverse, sides spined and toothed. Body dorsum smooth and shiny, sides cribrate with interstice retirugose. Body dorsum hairless.

Echinopla nitida occurs in the Moluccas.

Echinopla serrata group
Key to Echinopla serrata group workers - for the species occurring west of Weber's Line and described before 2018, i.e., Echinopla angustata, brevisetosa, fisheri, madli, rugosa, and wardi.


 * Echinopla arfaki
 * Echinopla angustata
 * Echinopla australis
 * Echinopla brevisetosa
 * Echinopla crenulata
 * Echinopla dubitata
 * Echinopla fisheri
 * Echinopla madli
 * Echinopla maeandrina
 * Echinopla octodentata
 * Echinopla praetexta
 * Echinopla rugosa
 * Echinopla serrata
 * Echinopla silvestrii
 * Echinopla turneri
 * Echinopla wardi

Eyes located behind midlength of head. Frontal lobes broad and triangular, laterally bluntly angled, concealing most of antennal fossae. Mesosoma dorsum convex, entire or interrupted by impressed metanotal groove. Mesosoma constricted at metanotal groove or not. Petiole transverse, sides and upper margin spined and toothed. Body surface densely cribrate with interstice coarsely retirugose. Body surface with abundant hairs and pubescence.

This group has a wide distribution from the Malay Peninsula to north-eastern Australia. The diagnosis of Xu & Zhou (2015) needs expansion for the biconvex mesosomal dorsum of E. fisheri.

Echinopla striata group

 * Echinopla charernsomi
 * Echinopla deceptor
 * Echinopla densistriata
 * Echinopla lateropilosa
 * Echinopla lineata
 * Echinopla pseudostriata
 * Echinopla senilis
 * Echinopla striata
 * Echinopla vermiculata

Eyes located close to posterior corners of head. Frontal lobes narrow and elevated, lateral margin straight, posterior corner broadly rounded, concealing half of antennal fossae. Mesosoma dorsum convex and interrupted by impressed metanotal groove. Mesosoma constricted at metanotal groove. Petiole transverse, sides and upper margin spined and toothed. Body dorsum longitudinally striate. Body surface with abundant hairs and pubescence.

Some infraspecific taxa of E. striata are probably distinct species. This is the group with the widest geographical distribution, reaching from southern China and the Nicobar Islands eastwards to New Guinea. The morphological definition needs expansion, because the body dorsum is – as an exception – not striate in E. lateropilosa.

Echinopla subtilis group

 * Echinopla subtilis

Head wider than long. Eyes positioned behind mid-length. Frontal lobes oriented horizontally, covering most of antennal fossae. Maxillary palpi extremely long. Dorsal outline of mesosoma almost forming a straight line, with sharp, narrow metanotal groove and complete promesonotal suture. Petiole with prominent lateral spines and dorsal crest bearing small teeth and tubercles. Irregularly winding impressed sculpture on dorsal surface of head and mesonotum. Gaster tergites with very fine, dense puncturation. Dorsal surface of body with white, relatively short setae.

The lone species in the group is from Borneo. It is distinct from all its congeners.