Cardiocondyla kagutsuchi

Seifert (2003) - K. Yamauchi (pers comm. 2001) reported for all six of his study sites on Okinawa, in Malaysia, and in Indonesia that this species nested in shallow soil in open, disturbed areas with bare or weakly herbaceous ground.

Identification
Seifert et al. (2017) - The basic morphology is similar to the condition described for Cardiocondyla itsukii from which it differs by a more elongated head. The morphological similarity to Cardiocondyla strigifrons is extreme in basically any character and there is no other option for reliable species separation than multivariate analyses using nearly all NUMOBAT characters. We omit a lengthy verbal description, which would not provide any help in species delimitation.

There is no doubt that species separation in the C. nuda group is difficult. It requires careful consideration of character definitions and the use high-resolution optical and measurement systems. The diagnose presented here uses numerous morphological characters to achieve an acceptable identification error rate.

Meeting the following definition:


 * Discriminant 176.328×PPH - 49.049×CW + 51.521×SP - 59.844×PPW + 6.61 < 0
 * Discriminant 214.193×PLG - 88.759×SP + 57.676×SL - 106.17×PEH - 10.465 > 0
 * Discriminant 319.279×PLG - 49.672×PPW + 133.938×FRS - 177.726×EYE + 91.370×CW - 63.848×SL - 12.955 < 0
 * Discriminant 75.783×PPH - 157.227×SP + 62.967×PPW - 117.467×SPBA + 101.708×EYE - 17.387 < 0

where:


 * CW: Maximum cephalic width; the maximum is found usually across and including the eyes, exceptionally posterior of the eyes.


 * EYE: Eye-size - the arithmetic mean of the large (EL) and small diameter (EW).


 * FRS: Distance of the frontal carinae immediately caudal of the posterior intersection points between frontal carinae and the lamellae dorsal of the torulus. If these dorsal lamellae do not laterally surpass the frontal carinae, the deepest point of scape corner pits may be taken as reference line. These pits take up the inner corner of scape base when the scape is fully switched caudad and produce a dark triangular shadow in the lateral frontal lobes immediately posterior of the dorsal lamellae of scape joint capsule (Fig. 1).


 * PEH: Maximum petiole height. The straight section of ventral petiolar profile at node level is the reference line perpendicular to which the maximum height of petiole node is measured at node level.


 * PLG: Mean length of pubescence hairs on dorsum of first gaster tergite as arithmetic mean of at least 7 measurements measured at magnifications of 320x.


 * PPH: Maximum postpetiole height; the lateral suture of dorsal and ventral sclerites is the reference line perpendicular to which the maximum height of postpetiole is measured.


 * PPW: Maximum width of postpetiole.


 * SL: Maximum straight line length of scape excluding the articular condyle given as the arithmetic mean of both scapes.


 * SP: Maximum length of propodeal spines; measured in dorsofrontal view along the long axis of the spine, from spine tip to a line that orthogonal to the long axis and touches the bottom of the interspinal meniscus (Fig. 3). Left and right SP are averaged. This mode of measuring is less ambiguous than other methods but yields higher spine length values in species with reduced spines. This is the case in the dentiform spines found in the C. nuda group where it is difficult to correctly define the long axis. In such cases, the deviation of the assumed spine axes from longitudinal mesosomal axis should not exceed 30°.


 * SPBA: Smallest distance of the lateral margins of the spines at their base. This should be measured in dorsofrontal view, since the wider parts of the ventral propodeum do not disturb the measurement in this position. If the lateral margins of spines diverge continuously from the tip to the base, a smallest distance at base is not defined. In this case SPBA is measured at the level of the bottom of the interspinal meniscus.

Distribution
This species is certainly of Indo-Malayan origin and, according to the close morphological proximity and mtDNA phylogeny, its closest relative is Cardiocondyla strigifrons. The distributional areas of C. kagutsuchi and C. strigifrons overlap considerably and no large differences in distribution are apparent. (Seifert et al., 2017)

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Guam, Indonesia, Malaysia, Micronesia (Federated States of), New Guinea, Northern Mariana Islands, Palau, Philippines, Solomon Islands. Oriental Region: Thailand, Vietnam. Palaearctic Region: China, Japan.

Biology
Seifert (2003) - Terayama (1999) and Yamauchi (pers comm., July 2000) stated that C. kagutsuchi from Japan and Okinawa (=Cardiocondyla nuda sensu Terayama & al. 1992, Terayama 1999) had a chromosome number of 2n = 28 (males n = 1 4) and only ergatoid males without a promesonotal suture. A restricted local population (= Cardiocondyla sp. 4 Terayama & al. 1992 = C. kagutsuchi Terayama 1999) from Omoto-dake, a small area on the Ishigaki island / Okinawa islands, was reported to have 2n = 27 (males n = 13) and to produce both alate and ergatoid males, the latter of which were said to have a distinct promesonotal suture. These chromosomal and demographic differences prompted Terayama (1999) to consider both populations as heterospecific. However, an accidental nature of the observed differences cannot be excluded. Furthermore the karyotype differences must not necessarily generate reproductive isolation since a correct meiotic pairing of a fused with two homologous unfused chromosomes and a correct subsequent disjunction to give balanced gametes i s possible. The high morphologic similarity of both populations is used here as argument to consider them as conspecific as long as the consistency of the karyotype differences and their possible consequences on reproductive isolation is not reasonably demonstrated. If a heterospecifity could be shown, C. nuda sensu Terayama & al. 1992 must be described as new species for reasons of its striking distinctness from C. nuda (Mayr, 1866).

Seifert et al. (2017) - In contrast to its sister species Cardiocondyla strigifrons, nest populations of C. kagutsuchi show both winged and ergatoid males (Yamauchi et al. 2005). Clonal production of both male and female sexuals and sexual production of workers is very likely for one mtDNA lineage of C. kagutsuchi in Japan (Okita et. al. 2016).

Nomenclature

 *  kagutsuchi. Cardiocondyla kagutsuchi Terayama, 1999d: 100, figs. 1-9 (w.q.m. ergatoid m.) JAPAN. See also: Seifert, 2003a: 252.

Worker
Seifert (2003) - Head elongated, CL/CW 1.182. Postocular index large, PoOc/CL 0.445. Eyes relatively small, EYE 0.230. Frontal carinae immediately caudal of FRS level parallel or very slightly converging. Foveolae on vertex without interspaces, deeply impressed, with 15 - 21 mm diameter, and with inner corona (flat tubercle) of 7 - 9 mm diameter. Longitudinal sculpture on vertex reduced; only frontal laminae, clypeus, and narrow area on anteromedian vertex finely longitudinally carinulate; weak semicircular rugosity is present around antennal fossae. Lateral area of mesosoma on whole surface regularly and strongly microreticulate; longitudinal sculpture except for 4 weak and short carinulae on metapleuron entirely absent; dorsal promesonotum with more irregular reticulum, whose meshes having twice the diameter than those on lateral area of mesosoma. Whole surface of petiole and postpetiole shining, but with very fine microreticulum. Cuticular surface of first gaster tergite shining and almost without microsculpture. Metanotal groove more or less shallow. Propodeal spines reduced to blunt dents. Petiole profile as in Cardiocondyla mauritanica, except for slender peduncle. Petiole node slightly longer than wide. Postpetiole narrower than in C. mauritanica; in dorsal view with distinctly angulate sides and straight anterior margin that is clearly shorter than posterior margin; differing from C. strigifrons by PPW/PPL 1.231 ± 0.029 [1.191 - 1.274] (n = 7); postpetiolar sternite flat. Colour polymorphism: most frequent light morphs with a yellowish to medium brown mesosoma and waist, head a little darker, gaster blackish brown, and antennal club dark brown; rarer dark morphs (Philippines) with blackish brown head and gaster and dark brown mesosoma and waist.

Queen
Seifert (2003) - Head of medium length, CL/CW 1.165. Scape longer than in Cardiocondyla mauritanica, SL/CS 0.807. Postocular index large, PoOc/CL 0.436. Occipital margin more or less straight. Frontal carinae parallel. Foveolae on vertex without interspaces, deeply impressed, with 17 - 19 mm diameter, and with inner corona or flat tubercle of 7 - 9 mm diameter. Longitudinal sculpture on vertex reduced; only frontal laminae, clypeus, and a narrow stripe on anteromedian area of vertex longitudinally carinulate; weak semicircular rugosity present around antennal fossae. Whole dorsal area of mesosoma densely and deeply foveolate-reticulate; lateral area of metapleuron with 6 - 8 longitudinal carinulae. Postpetiole notably foveolate, petiole only weakly sculptured. Spines very short. Shape of waist similar to C. mauritanica but petiolar peduncle more slender. Postpetiole with two anteroventral longitudinal carinulae and significantly lower than petiole: PEH/PPH 1.145 ± 0.045 [1.061, 1.227]. Postpetiole narrower than in C. mauritanica: PPW/CS 0.503. Pubescence longer and denser than in C. mauritanica. More or less concolourous dark to medium brown.

Type Material
Seifert (2003) - Ishigaki Island /Okinawa /Japan) [types investigated]. 6 worker paratypes labelled “Cardiocondyla kagutsuchi Terayama, 1999 \ Paratype \ Omoto-dake, Ishigaki-jima, Okinawa Pref.\ VII 1988, K. Yamauchi leg.”,.

References based on Global Ant Biodiversity Informatics

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 * Okita I., K. Murase, T. Sato, K. Kato, A. Hosoda, M. Terayama, and K. Masuko. 2013. The spatial distribution of mtDNA and phylogeographic analysis of the ant Cardiocondyla kagutsuchi (Hymenoptera: Formicidae) in Japan. Sociobiology 60(2): 129-134.
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