Cardiocondyla nigrocerea

Karavajev found his specimens on the island of Ambon under the bark of a rotten, fallen tree trunk. The biology of the population from Obi has been studied by Heinze et al. (2010): The nests were found in a secondary rain forest along a river and consisted of small chambers about 1–2 cm deep in the soil and had a single tiny entrance hole. Each nest contained a single dealate queen, several winged female sexuals, approximately 20 to 80 workers, and brood. One colony had an ergatoid male. The males are ergatoid and have sickle-shaped mandibles which they use to grab and kill rival males. Males reared in the laboratory were frequently moving on the brood pile apparently patrolling and antennating it for the presence of freshly eclosed female sexuals or rival males. They grasped young males with their sickle-shaped mandibles, held it for several minutes and besmeared it with secretions from the tips of their gasters. The attacked males died either directly from the attack of the dominant male or from the attack by workers whose aggression was elicited by the applied secretion. (Seifert, 2022)

Identification
Seifert (2022) - Worker: Smaller than Cardiocondyla wheeleri, CS 457 µm. Head moderately elongated, CL/CW 1.166. Outlines of posterior head in dorsal view rather rectangular, postocular distance moderate (PoOc 0.426), occipital margin slightly concave. Anterior clypeal margin between the level of frontal carinae concave. Scape short, SL/CS 0.816. Eye small, EYE/CS 0.224. Frons rather narrow (FRS/CS 0.272), frontal carinae immediately posterior of the FRS level almost parallel. Mesosoma in dorsal view concavely narrowing from the pronounced, but rather blunt pronotal corners caudad to anterior propodeum; dorsal mesosomal profile forming an almost straight line from anterior pronotum to spine tips, metanotal depression shallow (MGr/CS 0.90%. Spines moderately long and with rather large basal distance (SP/CS 0.314, SPBA/CS 0.347), in dorsal view their basal parts only weakly diverging and then weakly incurving caudad, in lateral view spine axis deviating by only 5° from longitudinal mesosomal axis—i.e., quasi parallel. Petiole very high (PeH/CS 0.379), disproportionately higher than postpetiole (PeH/PpH 1.502–1.582); in lateral view with a very short peduncle and a massive, roughly square-shaped node; petiole node in dorsal view clearly longer than wide, oval, narrowing frontad and above forming a keel. Postpetiole in dorsal view much wider than petiole (PpW/CS 0.541), with convex sides and deeply concave anterior margin; in lateral view much lower than petiole (PpH/CS 0.244), its sternite flat and without any prominent structure. Vertex with bicoronate foveolae of 13–17 µm diameter, the interspaces roughly as wide as foveolar diameter and with longitudinal microrugulae. Mesosoma in overall surface appearance matt, its dorsum finely corrugated-shagreened and its lateral surfaces finely microreticulate. Lateral surfaces of petiole finely microreticulate. Dorsum of postpetiole shiny, only with a very delicate microreticulum. First gaster tergite shiny but on its whole surface delicately microreticulate. Tergite pubescence short and dilute (PLG/CS 4.46%, sqPDG 5.97). Whole body light yellowish-grey except for the contrastingly blackish brown gaster.

Due to the unique combination of mesosomal and waist shape, Cardiocondyla nigrocerea is not to confuse with any species worldwide. Waist measurements alone are diagnostic: the ratio PeH/PpH∗PpW/PeW is 1.928 ± 0.248 [1.372, 2.908] in 2548 workers of any other species but 3.108 ± 0.069 [2.986, 3.151] in five workers of C. nigrocerea.

Distribution
Only known so far from the Indonesian islands of Ambon (3.72° S, 128.15° E, 120 m) and Obi (1.388° S, 127.601° E, 33 m). (Seifert, 2022)

Distribution based on Regional Taxon Lists
Indo-Australian Region: Indonesia.

Nomenclature

 * . Cardiocondyla nigrocerea Karavaiev, 1935a: 89, fig. 15 (w.) INDONESIA (Ambon I.).
 * Type-material: holotype worker.
 * Type-locality: Indonesia: Ambon I., 1912-13, no. 2745 (W. Karawajew).
 * Type-depository: SIZK.
 * Status as species: Chapman & Capco, 1951: 83; Bolton, 1995b: 132.
 * Distribution: Indonesia (Ambon).

Type Material
The taxon has been described from Ambon / Indonesia. Investigate by Seifert (2022)were one worker syntype labelled “Amboina Karavaiev\2745. Coll. Karavaievi\Cardiocondyla nigro-cerea Karav. typ.” and a second worker syntype labelled ”2745. Coll. Karavaievi\Cardiocondyla nigrocerea sp.n. Ambon”; both deposited in SIZ Kiev.

References based on Global Ant Biodiversity Informatics

 * Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
 * Heinze J., C. V. Schmidt, H. Nugroho, and B. Seifert. 2010. Wingless fighter males in the Wallacean ant Cardiocondyla nigrocerea (Insecta: Formicidae)/ The Raffles Bulletin of Zoology 58(2): 323-328.
 * Karavaiev V. 1935. Neue Ameisen aus dem Indo-Australischen Gebiet, nebst Revision einiger Formen. Treubia 15: 57-118.
 * Latumahina F., M. Borovanska, N. S. Putra, and M. Janda. 2015. Ants of Ambon Island  diversity survey and checklist. ZooKeys 472: 4357.