Crematogaster (Decacrema)

Blaimer, Bonnie B., 2010, Taxonomy and Natural History of the Crematogaster (Decacrema) - group (Hymenoptera: Formicidae) in Madagascar, Zootaxa 2714, pp. 1-39 : 14

Key to the workers of the Crematogaster (Decacrema) -group, Malagasy region

1. Petiole dorsally with postero-lateral tubercles, each bearing a single, stiff and long erect seta ( Fig. 21 a); postpetiole distinctly bilobed and broadly medially impressed, with a pair of dorso-posterior stiff, long erect setae ( Fig. 21 b); abdominal tergites 4–7 usually with scattered erect pilosity; mandibles with 4 teeth .................................................. 2

- Petiole dorsally lacking postero-lateral tubercle, setae commonly absent, if present (rare) then short and feeble; postpetiole variable, usually without erect setae; erect pilosity absent from abdominal tergites 4–7; mandibles with 4–5 teeth............................................................................................................................................................................... 3

2(1) Lateral portions of promesonotum raised with respect to median portion, and with postero-lateral carinate denticles and lateral carinae bordering metanotal groove, in lateral view promesonotum appearing dorsally flat ( Fig. 22 , or as in Fig. 37 b); widespread in western and southern dry and spiny forests .......................................................... C. grevei

- Lateral portions of promesonotum not raised with respect to median portion, postero-laterally rounded or angular and metanotal groove without lateral carinae, in lateral view promesonotum forming a more or less convex outline ( Fig. 23 , or as in Fig. 36 b); rare, montane forests of southern central Madagascar...................................... C. malala

3(1) Head and promesonotal sculpture well pronounced, deeply costulate ( Fig. 11 and 47 a) or areolate ( Fig. 9 and 48 a) .. .......................................................................................................C. hova- complex (morphotypes 4, 5, and part of 3)

- Head and promesonotal sculpture less developed, from reduced-aciculate ( Fig. 8 , or e.g. 44a) to reticulate ( Fig. 10 ), reticulate-areolate (e.g. Fig. 46 a) to weakly costulate .................................................................................................. 4

4(3) Face lacking erect setae except a single pair near frontal carinae; subpetiolar process developed as broad protuberance ( Fig. 25 and 38 b); small to medium size (HW 0.86–1.04, WL 0.80–1.05); propodeal spines small to medium size (SPI 0.15–0.20); sculpture on head and promesonotum always reduced-aciculate; northern, northwestern Madagascar and Ambohitantely forest. .......................................................................................................... C. nosibeensis

- Face with additional erect setae (careful, could be abraded) other than those close to frontal carinae; subpetiolar process variable; size highly variable, small to very large (HW 0.74–1.31, WL 0.78–1.34); propodeal spines variable (SPI 0.17–0.40), but commonly SPI> 0.20; sculpture variable. .................................................................................. 5

5(4) Subpetiolar process developed as acute, long tooth ( Fig. 24 and 39 b); promesonotal suture usually complete; medium to large size (HW 0.89–1.14, WL 0.91–1.12); propodeal spines small to medium size (SPI 0.17–0.21); head and promesonotal sculpture always reduced-aciculate; rare, known only from montane forests in R. S. Manongarivo ............................................................................................................................................................................. C. sisa

- Subpetiolar process variable, moderately articulated as angular dent ( Fig. 26 , 41 b, 49b, 50b, 52b and 53b), close to absent ( Fig. 27 and 51 b), or rarely as a broad protuberance ( Fig. 40 b); promesonotal suture often incomplete, if complete, then large to very large species (HW 1.09–1.21, WL 1.18–1.32); otherwise size highly variable; propodeal spines usually with SPI> 0.20; sculpture variable. ...................................................................................................... 6

6(5) Mesonotum postero-laterally distinctly angular to tuberculate ( Fig. 28 b and 30b, or as in 32b–35b); large to very large species (HW 1.09–1.31, WL 1.18–1.34); head usually reduced-aciculate, sometimes reticulate to feebly costulate; uncommon, central, eastern central and southeastern Madagascar. ................................................................... 7

- Mesonotum postero-laterally rounded or slightly tuberculate ( Fig. 29 , and as in 44b–48b), rarely angular; body size small to large (HW 0.74–1.19, WL 0.78–1.22); head sculpture variable, aciculate, reticulate or reticulate-areolate, if head sculpture reduced and aciculate, then usually at least promesonotal sculpture more developed; widespread throughout humid forests in Madagascar......................................C. hova- complex (morphotypes 1, 2, and part of 3)

7(6) Mesonotum raised with respect to pronotum and medially at least slightly tuberculate ( Fig. 30 a); promesonotal suture usually complete ( Fig. 31 a); head and promesonotal sculpture always aciculate. .............................. C. mahery

- Mesonotum usually not raised with respect to pronotum nor medially tuberculate ( Fig. 28 a), promesonotal suture usually incomplete ( Fig. 31 b) and only laterally impressed; head sculpture and promesonotal sculpture either aciculate or reticulate to weakly costulate............................................................................................................ C. sabatra *

Figures

FIGURES 21 – 31. Key to Malagasy Decacrema. 21 a: petiole with erect setae; 21 b: postpetiole distinctly bilobed and with erect setae; 22: promesonotum in lateral view flat; 23: promesonotum in lateral view convex; 24: subpetiolar process as acute tooth; 25: subpetiolar process as broad protuberance; 26: subpetiolar process as angular dent; 27: subpetiolar process absent; 28: mesonotum a: not raised in respect to pronotum b: postero-laterally angular, 29: mesonotum rounded postero-laterally; 30: mesonotum a: raised in respect to pronotum b: postero-laterally angular; 31: promesonotal suture a: complete b: incomplete.

FIGURES 32 – 37. Malagasy Crematogaster (Decacrema) species; a: full-face view, b: lateral view, c: dorsal view. 32: C. nosibeensis; 33: C. sisa; 34: C. sabatra; 35: C. mahery; 36: C. malala; 37: C. grevei.

FIGURES 1 – 11. Measurements and sculpture patterns. 1: head width, head length and eye length; 2: scape length; 3: length of hind tibia; 4: Weber’s length and spine length; 5: petiole length and petiole height; 6: petiole width, postpetiole width and postpetiole height; 7: mesonotal width and mesonotal length; 8: aciculate, 9: areolate, 10: reticulate, 11: costulate sculpture.

FIGURES 44 – 48. The Crematogaster (Decacrema) hova - complex; a: full-face view, b: lateral view, c: dorsal view. 44: morphotype 1; 45: morphotype 2; 46: morphotype 3; 47: morphotype 4; 48: morphotype 5.

FIGURES 38 – 43. Malagasy Crematogaster (Decacrema) species; a: petiole & postpetiole in dorsal view, b: petiole & postpetiole in lateral view. 38: C. nosibeensis; 39: C. sisa, 40: C. sabatra; 41: C. mahery; 42: C. malala; 43: C. grevei.

FIGURES 49 – 53. The Crematogaster (Decacrema) hova - complex; a: petiole & postpetiole in dorsal view, b: petiole & postpetiole in lateral view. 49: morphotype 1; 50: morphotype 2; 51: morphotype 3; 52: morphotype 4; 53: morphotype 5.