Ectomomyrmex Mayr, 1867

Yamane, Seiki, Hosoishi, Shingo & Ito, Fuminori, 2024, Taxonomic study on the queens of the Japanese ponerine genera, with a redescription of Ectomomyrmex horni restituted as a valid species (Hymenoptera: Formicidae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 64 (2), pp. 249-267 : 258-260

Ectomomyrmex Mayr, 1867

( Figs 3C , 5C , 7C )

Recognition. Body dark reddish brown; relatively large ants measuring 7.0–9.0 mm in total body length; head dorsum covered with dense striae that diverge posteriad; lateral face of head nearly flat; mandible without basal pit; subpetiolar process without anterior fenestra; mid- and hindtibiae with both simple and pectinate spurs.

Description of queen. Relatively large ants with total body length 7.0–9.0 mm and head width 1.73–2.10 mm. Head in full-face view almost as long as broad, with medially emarginate posterior margin, roundly convex lateral margins and weakly angled posterolateral corners; lateral face of head almost flat. Clypeus weakly convex anteriorly, with anteromedian portion concave. Malar space more than half major diameter of eye. Eye moderately large comprising 16–17 ommatidia along its longest axis, with rather sparse long hairs. Mandible triangular, without basal pit; masticatory margin with ca. 10 teeth of varying size. Antennal scape slightly surpassing posterior margin of head. With mesosoma in dorsal view scutoscutellar sulcus ‘broad’ with its median area rugose; parapsidal line faint; line running along posterolateral margin of mesoscutum deep and complete. With mesosoma in profile view metapleuron clearly delimited from mesopleuron with deep suture but fused with lateral face of propodeum. Propodeal spiracle with linear opening. Petiole subsquamiform; subpetiolar process not differentiated from sternite proper, ventrally round, without fenestra. Prora small and round, simple prominence. Gastral constriction moderately strong; pretergite and presternite of gastral segment II with very fine transverse striation; cinctus absent. Mid- and hindtibiae with simple spur and longer pectinate spur. Hindwing with jugal lobe. Entire body dark reddish brown to blackish brown.

Caste differences. Among the Japanese ponerine genera Ectomomyrmex is an exceptional genus in which the worker has a mesopleuron that is divided into upper and lower sections by a groove. In this respect the worker and queen do not differ, but the suture is broader and deeper in the queen. In other characters the queen is also similar to the worker except for queen-specific thoracic structures, large eyes and complete set of ocelli in the former.

Remarks. The two Japanese species are similar to the Euponera species in general habitus and habitat preference, but the latter have a basal pit on the mandible and lack the jugal lobe at the base of the hindwing; however, note that in Ectomomyrmex the jugal lobe is often folded under the hindwing so that it is easily overlooked.

Species examined (2/2). Ectomomyrmex horni (Forel, 1913) and E. sp., both closely allied to E. javanus Mayr, 1867 .

Figures

Fig. 3. Habitus (queen) in profile view. A – Cryptopone sauteri (Wheeler, 1906) (Aman-dake, Hirado-jima, Nagasaki-ken, Kyushu, 7.ix.1982, K. Ogata & S. Eto leg.); B – Diacamma cf. indicum Santschi, 1920 (gamergate) (Ishimine, Naha-shi, Okinawa-jima, Okinawa Is., Okinawa-ken, 24.iv.1979, K. Ogata leg.); C – Ecto- momyrmex horni (Forel, 1913) (Campus of Kagoshima Univ., Kago- shima-shi, Kagoshima-ken, Kyushu, 21.ix.1992, Sk. Yamane leg.); D – Parvaponera darwinii (Forel, 1893) (Yui-dake, Amami-ôshima, Amami Is., Kagoshima-ken, 26.vii.2019, Sk. Yamane leg.); E – Ponera kohmoku Terayama, 1996 (Shiroyama, Kagoshima-shi, Kagoshima-ken, Kyushu, 24.x.1978, K. Ogata leg.).

Fig. 5. Habitus (queen) in dorsal view. A – Cryptopone sauteri (Wheeler, 1906); B – Diacamma cf.indicum Santschi, 1920 (gamerga- te); C – Ectomomyrmex horni (Forel, 1913); D – Parvaponera darwinii (Forel, 1893); E – Ponera kohmoku Terayama, 1996. (Collection data same as in Fig. 3).

Fig. 7. Head (queen) in full-face view. A – Cryptopone sauteri (Wheeler,1906);B–Diacammacf.indicumSantschi,1920(gamergate); C – Ectomomyrmex horni (Forel, 1913); D – Parvaponera darwinii (Forel, 1893); E – Ponera kohmoku Terayama, 1996. (Collection data same as in Fig. 3).