Crematogaster

Heike Feldhaar, Ulrich Maschwitz & Brigitte Fiala, 2016, Taxonomic Revision of the Obligate Plant-Ants of the Genus Crematogaster Lund (Hymenoptera: Formicidae: Myrmicinae), Associated with Macaranga Thouars (Euphorbiaceae) on Borneo and the Malay Peninsula, Sociobiology 63 (1), pp. 651-681 : 658-659

Synonymic list of Crematogaster ( Crematogaster borneensis - group) species from Borneo and the Malay Peninsula obligately associated with Macaranga

In this study eight species of Crematogaster ( Crematogaster borneensis -group) are recognized (including five new species), belonging to three species subgroups. Species subgroups were designated based on morphological characters of the queen caste, i.e. queens of the decamera -subgroup are smaller (WL ranging from 1.7 to 2.3 mm) and have relatively smaller compound eyes (EL<0.5 mm) than queens of the captiosa -subgroup (WL ranging from 2.2 to 2.9 mm and EL> 0.5 mm) ( Feldhaar et al., 2003a; Feldhaar et al., 2010) (see Table S.1 for comparison of morphospecies designations used by our group and synonymized or new species names).

All workers of Crematogaster ( Crematogaster borneensis - group) workers including those associated with Macaranga have ten antennal segments. The workers of the Macaranga - associated Crematogaster species are all monomorphic. This is in contrast to the other three described species belonging to the former Decacrema from SE-Asia ( C. angulosa , C. biformis and C. cephalotes ) that all have dimorphic workers (see Supplementary Fig S2.1A to S2.3B). Body size may vary strongly within species although this is dependent on colony size (e.g. TL ranges from ~ 2.1 mm to 3.3 mm in Crematogaster captiosa workers). Thus, especially in workers relative measures (e.g. SI or RLEG) are more important characters than absolute measurements (e.g. SL or LHT) (see overview of most important distinguishing characters of workers in Table 1 ). Workers collected from small colonies are also lighter in colour. In queens shade of body coloration is a useful character, as are absolute measures. If possible, queens should be used for determination as worker characteristics are sometimes less distinctive (see overview of most important characters distinguishing queens in Table 1 ).

Most of the diversity of the species is apportioned between the decamera -subgroup and the captiosa -subgroup. The placement of C. maryatii is unclear. In the molecular phylogeny based on mitochondrial DNA this species does not cluster with either group and came out most basal. Based on nuclear DNA (elongation factor 1α) ( Feldhaar et al., 2010) this species is not separated from species of the captiosa -group. However, queen morphology and life-history characters resemble that of the decamera -group. Small size of queens and workers and early onset of reproduction may be a convergent trait though as this seems to enable usage of less productive and slow growing host plants ( Feldhaar et al. 2010). Therefore, we currently do not place C. maryatii in either group.

Crematogaster maryatii sp. nov.

C. decamera -subgroup

Crematogaster decamera Forel, 1910

Crematogaster hullettii sp. nov.

Crematogaster roslihashimi sp. nov.

C. captiosa -subgroup

Crematogaster borneensis André, 1896

= C. borneensis subsp. capax Forel, 1911 syn. nov.

= C. borneensis subsp. hosei Forel, 1911 syn. nov.

= C. borneensis subsp. sembilana Forel, 1911 syn. nov.

= C. borneensis var. macarangae Viehmeyer, 1916 syn.nov.

Crematogaster captiosa Forel, 1910

= C. borneensis var. harpyia Forel, 1911 syn. nov.

= C. borneensis var. insulsa Forel, 1911 syn. nov.

= C. borneensis subsp. symbia Forel, 1911 syn. nov.

= C. borneensis subsp. novem Forel, 1911 syn. nov.

Crematogaster linsenmairi sp. nov.

Crematogaster claudiae sp. nov.

Tables

Table 1. Overview of most distinct morphological characters of the Macaranga - associated Crematogaster (borneensis - group) species.

Species	Worker characters	Queen characters
C. borneensis	Propodeal spines present Scape index (SI)> 0.65 RLEG <0.7, rarely above	EL> 0.5 mm (to 0.6mm) REL 0.36 - 0.43 OD1> OW Head longer than wide (CI <0.95)
C. linsenmairi	Propodeal spines present Scape index (SI)> 0.65 RLEG> 0.7, rarely below	EL rarely <0.65mm REL 0.39 - 0.48 OD1 <OW Scape length>0.75 mm
C. hullettii	Propodeal spines present Scape index (SI) <0.65 Head as wide as long (CI ~ 1.0) Legs relatively short, RLEG 0.58 to 0.62	EL 0.39 – 0.47 mm (rarely> 0.45) REL 0.32-0.4 OD1> OW ROD between 0.09 - 0.13
C. captiosa	Propodeal spines present Scape index (SI) <0.65 RLEG 0.61 to 0.69	EL ~ 0.6mm REL 0.38 - 0.48 OD1 <OW Scape length usually <0.75 mm
C. decamera	Propodeal spines absent Legs relatively long (RLEG 0.71 - 0.85) Head slightly longer than wide (CI 0.94 - 1.02) Postpetiole always wider than petiole (PI <1.0)	EL 0.39 - 0.45mm REL 0.29 - 0.35 OD1> OW SL> 0.7 mm CI usually> 1.0 PI <1.0
C. maryatii	Very short propodeal spines, sometimes absent Scape index (SI)> 0.65 Head slightly longer than wide (CI 0.94 - 1.02) Petiole as wide or wider than postpetiole, PI> 0.98 RLEG usually <0.7	EL 0.34 - 0.38mm REL 0.28-0.34 OD1> OW PI usually> 1.0 (to 1.12)
C. roslihashimi	Propodeal spines absent Scape index (SI)> 0.7 Head distinctly longer than wide (CI: 0.91) Legs realtively long (RLEG 0.71-0.73)	EL 0.3 – 0.32; REL <0.28 OD1> OW Elongated head (CI <0.9) PI ≤ 1.0
C. claudiae	Propodeal spines usually absent, when present very short Petiole distinctly wider than postpetiole (PI> 1.15) Legs and scapi short, RLEG <0.69 and SI <0.65	EL 0.45 - 0.5 mm (REL 0.36-0.39) OD1> OW PI> 1.0 ROD between 0.13 - 0.17