Cladomyrma petalae

Cladomyrma petalae, like all Cladomyrma species, are arboreal ants. This species nests in excavated vines and tree branches. The tropical forests where their hosts occur experience frequent and strong rains. The risk of rain and rain-runoff getting into C. petalae nests is mitigated in part by their laterally oriented nest-entrances. If water does get into a nest, it is removed using a water-bailing behavior. The workers ingest the liquid and regurgitate it to the outside until no standing water remains. (Moog et al., 1997)

Identification
Agosti et al. (1999) placed Cladomyrma species into two groups based on the shape of the queen's petiole, raised (an erect node or scale) or depressed (dorsally truncate and low). Cladomyrma petalae belongs to the depressed petiole group.

This species is distinguished from all other species in the queen caste by the shining dorsal part of the katepisternum, the lateral part of the propodeum below the spiracle being devoid of any pubescence, the small, narrow metapleural gland orifice, and the low, dorsally truncated petiole. There is variation in coloration and pilosity, including the pubescence.

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

Biology
This species has been found in a set of six syntopic host plants; the understory trees Saraca thaipingensis (Caesalpiniaceae), Drypetes longifolia (Euphorbiaceae), and Ryparosa fasciculata (Flacourtiaceae); and the woody climbers Strychnos vanprukii (Loganiaceae), Luvunga sp. (Rutaceae), and Spatholobus bracteolatus (Papilionaceae) (Maschwitz et al., 1991, Moog and Maschwitz, 1994, Moog et al., in press). Despite this highly diverse host range, both field studies and extensive examination of herbarium specimens have shown that congeneric host plant species are not colonized by C. petalae (Moog et al., in prep.). Preliminary results of ‘‘host acceptance’’ experiments with colony-founding queens collected from Saraca and Spatholobus and placed on one of the other syntopic host plants indicate that foundress queens sometimes accept an alternative host species (unpublished results). However, they do not accept any other plant species with suitable internodes (controls). The mechanisms underlying this surprising queen response to particular, taxonomically diverse host plants is not yet understood and needs further study. In Saraca (and other hosts), worker activity on the plant surface is concentrated on young developing foliage and the ants reduce herbivore damage to young leaves significantly (Moog and Maschwitz, 1994; unpubl. results). This species also precludes oviposition by female lycaenid butterflies. In addition, lycaenid larvae, even myrmecophilic ones, placed on leaf flushes and confronted with patrolling workers never survive (Seufert and Fiedler, 1996)

Nomenclature

 * mossyna. Cladomyrma mossyna Agosti, 1991: 307, figs. 14, 17, 22 (s.w.q.) BORNEO. Junior synonym of petalae: Agosti, Moog & Maschwitz, 1999: 13.
 *  petalae. Cladomyrma petalae Agosti, 1991: 308, figs. 13, 16, 20, 25, 26 (s.w.q.m.) WEST MALAYSIA. Senior synonym of mossyna: Agosti, Moog & Maschwitz, 1999: 13.

Description
Agosti et al. (1999):

Worker
Major worker. AL 0.86–1.42, HL 0.86–1.24, HW 0.78–1.16, EL 0.16–0.23, SL 0.38–0.60, CI 84–95, EI 18–21, SI 47–53 (n = 18).

Clypeus with longitudinal sculpture; gastral pubescence dense and regular; erect pilosity all over alitrunk, without a distinct increase on the propodeum; short, erect hairs on gaster, mainly along posterior margin of tergites, but with scattered hairs in between; erect hairs white. Minor worker.

AL 0.60–0.98, HL 0.63–0.86, HW 0.53–0.82, EL 0.12–0.18, SL 0.31–0.44, CI 84–95, EI 19–26, SI 48–65 (n = 18).

Clypeus without longitudinal sculpture, smooth; few long erect hairs on dorsal face of propodeum; very dense decumbent pubescence on gaster; body color dark brown, with propodeum and petiole slightly brighter; small body size.

Queen
AL 2.26–2.56, HL 1.42–1.56, HW 1.15–1.27, EL 0.46–0.54, SL 0.66–0.72, CI 81–84, EI 38–43, SI 53–59 (n = 18). Holotype: Queen AL 2.56, HL 1.51, HW 1.24, SL 0.72, EL 0.52, CI 82, EI 42, SI 58.

Dorsal part of an- and katepisternum without erect hairs; very flat, dorsally truncate petiole; very few erect hairs on base of first gastral tergite; coloration variable, even within one nest, from uniform yellowish with darker posterior margins of gastral tergites to completely dark brown; in most cases at least genae lighter colored.

Type Material
Holotype queen, W-MALAYSIA, Selangor, Ulu Gombak, 1/12/1990, Joachim Moog, ex: Saraca thaipingensis,. Holotype queen, W-MALAYSIA, Selangor, Ulu Gombak, 11/1/1988, Ulrich Maschwitz, #873, ex: Saraca thaipingensis, BMNH.

References based on Global Ant Biodiversity Informatics

 * Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58