Cardiocondyla obscurior

Cardiocondyla obscurior
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Crematogastrini
Genus:	Cardiocondyla
Species:	C. obscurior
Binomial name
Cardiocondyla obscurior Wheeler, W.M., 1929 Specimen labels
Synonyms
Cardiocondyla bicolor Donisthorpe, 1930

Seifert (2003) - C. obscurior was reported to nest in cavities of bushes and trees 2 - 5 m above the ground level; it was found in dead twigs of trees such as Erythrina variegata (Okinawa), in dwarf coconuts (Brazil), galls of Acacia trees (Brazil), in a dead twig on a tree (Florida), on a Ficus tree (Israel), in the gall of a Tamarix bush (Israel), and in the cavity of a coconut high in the tree (Zanzibar).

Identification

Seifert (2003) - A member of the Cardiocondyla wroughtonii group. The workers of C. obscurior differ from Cardiocondyla wroughtonii by darker gaster pigmentation, shorter head, smaller postocular distance, narrower frons, wider and higher waist segments, wider spine base distance, and shorter spine length.

Keys including this Species

• Key to Holartic Cardiocondyla
• Key to Micronesian Ants
• Key to Palaearctic Cardiocondyla
• Key to US Cardiocondyla species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Comoros.
Indo-Australian Region: American Samoa, Fiji, Guam, Micronesia (Federated States of), New Guinea, Northern Mariana Islands, Singapore.
Nearctic Region: United States.
Neotropical Region: Barbados, Bermuda, Brazil, Costa Rica, Grenada, Guadeloupe, Mexico, Netherlands Antilles.
Oriental Region: Nepal, Taiwan (type locality).
Palaearctic Region: Canary Islands, Cyprus, Hungary, Israel.

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.

Biology

Worker from Boston, Massachusetts.

Seifert (2003) - C. obscurior produce alate and ergatoid males (Yamauchi in lit. 3 July 2000, my own material). Average differences in chromosome numbers seem to exist but the numbers are not constant. C. wroughtonii from the Okinawa Islands had 2n = 56 chromosomes while sympatric C. obscurior had 2 n = 52 chromosomes (Yamauchi in lit., 3 July 2000). A C. obscurior sample from Gainesville/Florida had 2n = 48 (Francoeur in lit., 19 October 2000). Colonies may have more than one queen. New nests can be formed by fission.

Fuessl et al. (2018) - Cardiocondyla obscurior is characterized by a male diphenism, with winged disperser males and wingless (‘ergatoid’) fighter males (Kugler, 1983; Heinze, 2017). The latter are present in colonies year-round and compete fiercely for monopolization of mating chances with virgin queens (Kinomura &Yamauchi, 1987; Stuart et al., 1987). Under environmentally adverse conditions, colonies also produce the more peaceful, winged disperser males, the male phenotype typical for most ant species (Cremer et al., 2003). Interestingly, mating with a winged male prolongs female life span more than mating with an ergatoid male (Schrempf & Heinze, 2008). Furthermore, sperm traits show considerable variation between winged and wingless males (Schrempf et al., 2016; Metzler et al., 2018) and the two phenotypes might potentially experience different levels of sperm competition because they differ in abundance in natural nests (for preliminary data on single-mating by C. obscurior queens, see Schmidt et al., 2016).

In the present study, we investigate the proteins produced by the accessory glands of the two male phenotypes. The seminal fluid of insect males is known to contain a complex mixture of proteins with multiple functions in sperm protection, antimicrobial defence and the induction of multiple changes in female physiology (Avila et al., 2011). Our proteomic and transcriptomic study reveals that the seminal fluid and themale accessory glands of the male-diphenic ant C. obscurior contain several hundred proteins, of which many appear to differ in quantity between winged and ergatoid males. More than 20 proteins showing considerable overlap with other studies on insect seminal fluids. One example includes proteolysis regulators, such as serine proteases, carboxypeptidases and serine protease inhibitors (serpins), which all are common accessory gland proteins of insects (Ravi Ram & Wolfner, 2009; Mueller et al., 2005; Baer et al., 2009a; Xu et al., 2013; LaFlamme & Wolfner, 2013; Yu et al., 2016; Bayram et al., 2017). Although their function in C. obscurior remains to be determined,male-derived serine proteases are suggested to stimulate egg laying and other post-mating changes in the female of various insects (LaFlamme & Wolfner, 2013).

Cremer and Heinze (2002) examined evolutionary implications of the unusual occurrence of dimorphic male production in C. obscurior and the mating strategies these males pursued. Abstract: Hamilton's concept of local mate competition (LMC) is the standard model to explain female–biased sex ratios in solitary Hymenoptera. In social Hymenoptera, however, LMC has remained controversial, mainly because manipulation of sex allocation by workers in response to relatedness asymmetries is an additional powerful mechanism of female bias. Furthermore, the predominant mating systems in the social insects are thought to make LMC unlikely. Nevertheless, several species exist in which dispersal of males is limited and mating occurs in the nest. Some of these species, such as the ant C. obscurior, have evolved dimorphic males, with one morph being specialized for dispersal and the other for fighting with nest–mate males over access to females. Such life history, combining sociality and alternative reproductive tactics in males, provides a unique opportunity to test the power of LMC as a selective force leading to female–biased sex ratios in social Hymenoptera. We show that, in concordance with LMC predictions, an experimental increase in queen number leads to a shift in sex allocation in favour of non–dispersing males, but does not influence the proportion of disperser males. Furthermore, we can assign this change in sex allocation at the colony level to the queens and rule out worker manipulation.

Atchison & Lucky (2022) found that this species does not remove seeds.

Life History Traits

• Queen number: polygynous (Cournault & Aron, 2009)

Castes

Worker

Images from AntWeb

Worker. Specimen code casent0103429. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by LACM, Los Angeles, CA, USA.

Worker. Specimen code casent0103430. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by LACM, Los Angeles, CA, USA.

Worker. Specimen code casent0119909. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by CAS, San Francisco, CA, USA.

Queen

Images from AntWeb

Queen (alate/dealate). Specimen code casent0147012. Photographer Erin Prado, uploaded by California Academy of Sciences.	Owned by CAS, San Francisco, CA, USA.

Queen (alate/dealate). Specimen code casent0172616. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by LACM, Los Angeles, CA, USA.

Male

Diploid males are known to occur in this species (found in 1.5% of 67 examined nests) (Schrempf et al., 2006; Cournault & Aron, 2009).

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

• obscurior. Cardiocondyla wroughtoni var. obscurior Wheeler, W.M. 1929g: 44 (w.q.) TAIWAN.
  • Type-material: 1 syntype worker, 1 syntype queen.
  • Type-locality: Taiwan (“Formosa”): Eisei (F. Silvestri).
  • Type-depository: MCZC.
  • Junior synonym of wroughtonii: Lin & Wu, 2003: 63.
  • Subspecies of wroughtoni: Wheeler, W.M. 1930a: 98; Chapman & Capco, 1951: 84; Bolton, 1995b: 133.
  • Status as species: Seifert, 2003a: 271 (redescription); Wetterer & Vargo, 2003: 417; Wetterer & Wetterer, 2004: 215; Clouse, 2007b: 230; Terayama, 2009: 179; Vonshak, et al. 2009: 41; Ellison, et al. 2012: 235; Sarnat & Economo, 2012: 74; Hita Garcia, et al. 2013: 208; Borowiec, L. 2014: 48; Ramage, 2014: 171; Bharti, Guénard, et al. 2016: 34; Wetterer, et al. 2016: 10; Deyrup, 2017: 56; Wang, W.Y., Soh, et al. 2022: 69.
  • Senior synonym of bicolor: Seifert, 2003a: 271.
  • Distribution [tramp species]
  • Afrotropical: Kenya.
  • Malesian: Hawaii, Micronesia, Singapore.
  • Nearctic: U.S.A.
  • Neotropical: Bermuda, Brazil, Puerto Rico, Virgin Is.
  • Oriental: India, Japan, Nepal, Taiwan.
  • Palaearctic: Germany, Israel, Spain.
• bicolor. Cardiocondyla bicolor Donisthorpe, 1930b: 366 (w.) ISRAEL.
  • Type-material: holotype worker, 5 paratype workers.
  • Type-locality: Israel (“Palestine”): (no further data), 1930 (Scheinkin & J. Carmin).
  • Type-depository: BMNH.
  • Status as species: Menozzi, 1933b: 93.
  • Junior synonym of wroughtonii: Kugler, J. 1984: 6; Bolton, 1995b: 132; Zhou, 2001b: 86.
  • Junior synonym of obscurior: Seifert, 2003a: 271.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Characterized by its dark color, the body and appendages being dull brown, the legs scarcely paler, the antennal clubs distinctly infuscated, the Whole gaster dark brown, except the posterior borders of the segments, which are paler.

Seifert (2003) - Small size CL 428. Head very short, CL/CW 1.108. Scape short, SL/CS 0.780. Postocular index rather large, PoOc/CL 0.435. Eyes medium-sized, EYE 0.232. Frons wide, FRS/CS 0.270, frontal carinae immediately behind FRS level parallel or slightly diverging. Anterior clypeal margin between level of frontal carinae frequently slightly notched; median occipital margin usually slightly concave; overall head shape posterior of eyes less rounded than in Cardiocondyla wroughtonii. Whole head and mesosoma without any notable rugosity. Paramedian and lateral areas of vertex with deep (sometimes shallower) foveolae of 17 - 21 mm diameter, frequently in dense honey-comb like arrangement, usually showing an inner corona of 9 mm diameter; median vertex weakly foveolate-carinulate. Whole surface of mesosoma and waist densely foveolate-reticulate, the meshes with lower diameters than ort vertex. Metanotal groove in lateral view usually with rather steep anterior and posterior slopes, occasionally shallower than in C. wroughtonii. Propodeal spines long, shorter than in C. wroughtonii, SP/CS 0.178; outer spine base distance wider than in C. wroughtonii, SPBA/CS 0.293. Petiolar peduncle in lateral aspect deviating 30° from longitudinal axis of petiole node that is often more square-shaped than in C. wroughtonii. Postpetiole as a rule more massive than in C. wroughtonii, as in this species with characteristic anteroventrolateral corners; in dorsal view, convex sides meeting concave anterior margin in distinct angle. Head, mesosoma, and waist brightly yellowish or yellowish brown, antennal club usually notably infuscated. In contrast to dark morph of C. wroughtonii, all gaster segments dark blackish brown, PigG1 98 ± 4 %.

Queen

The single specimen of this sex is dealated and headless and is perhaps immature, the body is paler and more yellowish than in the worker, except the tegulae, which are black and the gaster, which is dark brown throughout, with paler posterior borders to the segments.

Seifert (2003) - Very small size, CS 460. Head very short, CL/CW 1.122. Postocular index shorter than in Cardiocondyla wroughtonii, PoOclCL 0.423. Scape rather short, SL/CS 0.755. Median occipital margin and anterior clypeal margin between level of frontal carinae straight or slightly concave. Frontal carinae immediately caudal of FRS level diverging or subparallel. With exception of 4 - 5 longitudinal rugae on metapleuron, whole head and mesosoma without any rugosity. Paramedian area of vertex with deep, densely arranged foveolae of 18 - 22 mm diameter, showing inner coronae of 9 mm diameter. Whole surface of mesosoma and waist densely foveolate, foveolae on dorsal mesosoma similar to those on vertex, those on lateral area of mesosoma and in particular on waist with significantly lower diameters. Propodeal spines long, but shorter than in C. wroughtonii, SP/CS 0.187, ratio SPBA/SP 1.942 ± 0.138 (n = 8). Postpetiole with sharp anteroventrolateral corners; in dorsal view, its convex sides meet the concave anterior margin in a distinct corner. Head, mesosoma, and waist yellowish, small patches at wing insertions notably darker; antennal club frequently infuscate; all gaster segments on whole surface brown to dark blackish brown.

Type Material

One worker and one female from Eisei, Formosa.

Seifert (2003) - Three investigated gynes from the Museum of Comparative Zoology collection, labelled by Wheeler “Kagi, Formosa 11.1.1927 R.Takahashi Wm. M. Wheeler\ Cotypes\ var. obscurior Wheeler” fully match the conception of C. obscurior presented here but cannot be considered as genuine type material. These gynes were the basis of a second description, published on 7 March 1 930 (Wheeler 1930). Wheeler's first description, published on 22 October 1929, was based upon one worker and a headless dealate queen collected at Eisei / Formosa (Wheeler 1929). These specimens were not available from MCZ Cambridge and are believed to be lost.

References

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