Genus Crematogaster - Subgenus Decacrema
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The Ants of
Africa Genus Crematogaster - Subgenus Decacrema |
| Genus Crematogaster Introduction |
Subgenus Decacrema Forel (1910f: 9)Diagnostic Features - The only subgenus with
10-segmented
antennae. Forel's (1910f) subgenus definition is at |
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These can be divided into two distinct species groups. |
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Note: Blaimer, Bonnie B., 2010. Taxonomy and Natural History
of the Crematogaster (Decacrema)-group (Hymenoptera:
Formicidae) in Madagascar. Zootaxa,
2714, 1-39 (available on
line as free access). She listed C. arthurimuelleri Forel, C. edentula Santschi, C. lango Weber, C. liengmei Forel (incl. 2 subspecies), C. petiolidens Forel and C. solenopsides Emery (incl. 3 subspecies) from Sub–Saharan Africa. and observed "The morphology of all but one examined African species further refutes a close relationship to the Decacrema of Madagascar (Blaimer, pers. observ.) and warrants further study". Blaimer's key to Malagasy species separates into two groups; the first with the petiole with potero-lateral tubercles and paired coarse erect hairs on both petiole and postpetiole; the second without an angular petiole and usually with the erect hairs. My key predates hers but the same separation applied to African species matches my couplet 2 with her second group; and my couplet 3-onwards with her first group. She listed liengmei
as among those she examined and my specimens show the similarity to the
Malagasy species she recognised. Further, it seems likely the true Decacrema are of second group,
which includes the genus type-species, C, schencki. Thus, at some future
point the first group of African species might merit placement in a
separate subgenus. |
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Key to species - workers |
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MYRMICINAE Introduction |
© 2007, 2008, 2010, 2012, 2014, 2015, 2016 - Brian
Taylor
CBiol
FRSB FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. |
href="decacrema.htm"
Antenna with scapes
reaching
the occiput, funiculus with a 3-segmented club; head and alitrunk with
distinct sculpturation giving those parts a semi-matt appearance; base
colour dark-brown to black; TL at least 3.0 mm
Propodeum
without teeth; TL 2.0-2.5 mm; shiny, colour light rust-brown, antennae
and legs yellowish, 
Petiole
with only a small anterior subventral tooth; TL only 1.9 mm; propodeal
teeth triangular and flat; overall shiny; few erect hairs; bright
light brown, appendages more yellow
TL ca 2.5 mm; brown
TL
1.6-2.0 mm; head rectangular about one-fifth longer
than wide; eyes small with no more than 12 facets; propodeal spines
short andt triangular with a wide base, height equal to base;
petiole square with teeth at each angle, the anterior pair small but
the posterior pair very distinct; subpetiolar anterior tooth not
mentioned; rust or reddish with head and gaster brown
TL at least 3.0 mm; head near square in full face view, propodeal spines
long; overall shiny yellow-brown
TL at least 3.0 mm; propodeal spines
long; overall shiny yellow-brown
TL
2.0 mm; head
slightly longer
than wide, laterally convex; eyes flat; promesonotum convex; propodeal
spines a little longer than one-third their basal separation;
propodeum laterally bordered; lateral mesonotum and propodeum
distinctly but finely punctate; petiole trapezoidal, with the anterior
and posterior angles dentate, subtended by an almost horizontal tooth;
dark brown, gaster brown-black, appendages brownish-red; characterised
by quite abundant and moderately long erect hairs on head and alitrunk
TL 2.5 mm; head
slightly longer than wide; eyes large, set
at midpoint of head; alitrunk convex; no pubescence, very few erect
hairs; shiny clear brown colour, anterior of head and gaster darker