Crematogaster degeeri Forel, 1886

Blaimer, Bonnie B. & Fisher, Brian L., 2013, Taxonomy of the Crematogaster degeeri-species-assemblage in the Malagasy region (Hymenoptera: Formicidae), European Journal of Taxonomy 51, pp. 1-64 : 23-27

Crematogaster degeeri Forel, 1886

Figs 8-9

Crematogaster degeeri Forel, 1886 : cvii.

Crematogaster (Acrocoelia) degeeri var. lunaris Santschi, 1928: 64 . Worker from MADAGASCAR: Mont. Voiposa , Ambohimahosoa (Descarpentries, leg.) [ NHMB, examined] . Lectotype worker by present designation [CASENT0101174, image on AntWeb]. syn. nov.

Crematogaster degeeri – Forel 1891: 190 (queen and male described).

Crematogaster geeri – Schulz 1906: 155; unjustified subsequent emendation.

Crematogaster (Crematogaster) degeeri – Wheeler 1922b: 1022. — Bolton 1995: 166.

Crematogaster (Acrocoelia) degeeri – Emery 1922: 146.

Diagnosis

Within the C. degeeri -assemblage, this species is most easily recognized by its large eyes (OI 0.22 - 0.26), fairly long propodeal spines (SPI 0.10 - 0.16), and a promesonotum that usually bears angular posterolateral denticles ( Fig. 5C ) and is distinctly set off from propodeum in lateral view. Crematogaster degeeri could be confused with C. ramamy sp. nov. and C. dentata stat. nov., but in both of the latter the promesonotum is not distinctly set off from the propodeum. Furthermore, the latter two species have generally shorter propodeal spines ( C. dentata stat. nov. SPI 0.01 - 0.10; C. ramamy sp. nov. SPI 0.07 - 0.12).

Mean barcode divergences between C. degeeri and species within the C. degeeri -assemblage are 13.2 - 18.0 %, except with regard to C. ramamy , where this level is only 4.7% ( Table 3 ). In our analysis, C. degeeri is paraphyletic with respect to C. ramamy (see comments below).

Type material examined

( MHNG) MADAGASCAR (M. Grandidier), 2 worker syntypes. Lectotype worker by present designation: top worker of these two specimens on one pin [ CASENT0101690 ; imaged on AntWeb].

Other material examined

( CASC, MCZC, MHNG, NMBH, PSWC): refer to Supplementary Material 1.

Worker

Measurements

(n = 15) HW 0.81 - 1.05; HL 0.76 - 0.97; EL 0.18 - 0.24; SL 0.63 - 0.78; WL 0.81 - 1.09; SPL 0.08 - 0.16; PTH 0.17 - 0.22; PTL 0.25 - 0.33; PTW 0.28 - 0.41; PPL 0.14 - 0.20; PPW 0.24 - 0.33; LHT 0.60 - 0.81; CI 1.06 - 1.11; OI 0.22 - 0.26; SI 0.77 - 0.86; SPI 0.10 - 0.16; PTHI 0.56 - 0.77; PTWI 1.01 - 1.39; PPI 1.52 - 1.95; LBI 1.29 - 1.44.

Description

( Fig. 8A - C ) Small to medium size (HW 0.81 - 1.05, WL 0.81 - 1.09).

Masticatory margin of mandibles with four teeth; head shape quadrate, mostly as long as wide (CI 1.06 - 1.11); posterior margin of head in full-face view laterally rounded or subangular; occipital carinae usually distinct; antennal scapes reaching or surpassing head margin; midline of eyes situated slightly above midline of head in full-face view; eyes fairly large (OI 0.22 - 0.26) and moderately protruding.

Pronotum laterally angular; promesonotal suture indistinct; mesonotum more or less forming one plane with pronotum, but often the two separated by distinct variation in sculpture (see below); mesonotum usually with a short posterior face; laterally mesonotum angular to carinate, and often with posterolateral denticles, which set off the promesonotum distinctly from propodeum; posterior face of mesonotum longitudinally depressed with respect to lateral carinae, slopes gently into metanotal groove; metanotal groove fairly shallow, laterally constricted; propodeal spines short, spiniform (SPI 0.10 - 0.16), usually straight and moderately diverging; propodeal spiracles large, situated directly at base of spines; dorsal face of propodeum convex, almost as long as posterior face; posterior face of propodeum gently sloping; petiole in dorsal view from moderately to strongly flared and usually strongly concave, dorsolaterally carinate but without posterolateral tubercules or denticles; subpetiolar process variable; postpetiole wider than long, very distinctly bilobed by a sharp median impression; subpostpetiolar process absent.

Head sculpture shiny to aciculate; pronotum usually dorsally costulate and contrasting abruptly with a shiny to aciculate mesonotum; propleuron aciculate or reticulate, mesopleuron areolate, metapleuron mostly carinulate; dorsal face of propodeum carinulate or reticulate, posterior face shiny; dorsal face of petiole reticulate; helcium reticulate; postpetiole dorsally aciculate-reticulate; lateral and ventral face of petiole and postpetiole reticulate; face usually with four to eight erect, longer setae, and regular shorter appressed to suberect pubescence; erect pilosity on promesonotum variable, usually <eight long setae; otherwise promesonotum dorsally with regular appressed to subdecumbent pubescence; petiole and postpetiole usually with a pair of short erect setae posterolaterally, and shorter suberect, decumbent or appressed pubescence; abdominal tergites four to seven with very sparse, short, erect pilosity, more abundant and longer on sternites four to seven, and abundant appressed to decumbent pubescence throughout. Color reddish brown to dark brown or black.

Queen

Measurements

(n = 3) HW 1.44 - 1.56; HL 1.32 - 1.42; EL 0.40 - 0.45; SL 0.95 - 0.99; MSNW 1.20 - 1.46; MSNL 1.42 - 1.50; WL 2.49 - 2.68; SPL 0.00; PTH 0.38 - 0.41; PTL 0.43 - 0.53; PTW 0.51 - 0.59; PPL 0.35 - 0.38; PPW 0.56 -

0.60; LHT 1.12 - 1.14; CI 1.09 - 1.10; OI 0.28 - 0.32; SI 0.68 - 0.72; MSNI 0.83 - 0.97; SPI 0.00; PTHI 0.72 - 0.95; PTWI 1.06 - 1.27; PPI 1.53 - 1.60; LBI 2.23 - 2.37.

Description

( Fig. 8D - F ) Medium size (HW 1.44 - 1.56, WL 2.49 - 2.68). With worker characters, except as follows.

Masticatory margin of mandibles with five teeth. Antennal scapes not reaching posterior margin of head, but surpassing level of lateral ocelli; eyes large (OI 0.28 - 0.32), situated at midline of head in full-face view; head shape fairly quadrate (CI 1.09 - 1.10), moderately tapering from posterior to anterior margin; posterior margin straight.

Mesosoma fairly compact (MSNI 0.83 - 0.97, WL 2.49 - 2.68); mesoscutum in dorsal view about as wide as long; dorsal face of propodeum distinct but short; propodeum tuberculate but distinct spines absent; petiole moderately flared, postpetiole merely impressed behind; subpetiolar process variable.

Sculpture shiny to aciculate throughout; face with four to six longer erect setae and abundant shorter erect to suberect pilosity; mesonotum with abundant, short, and scattered longer erect setae; petiole and postpetiole with very dense short suberect pilosity, and postpetiole often with additional longer dorsoposterior setae; abdominal tergites and four to seven with abundant appressed pilosity and regular, short, erect pilosity. Color similar to respective workers; wings clear.

Male

Measurements

(n = 1) HW 0.74; HL 0.51; EL 0.29; SL 0.12; MSNW 0.91; MSNL 0.82; WL 1.53; SPL 0.00; PTH 0.24; PTL 0.26; PTW 0.30; PPL 0.19; PPW 0.35; LHT 0.86; CI 1.46; OI 0.57; SI 0.24; MSNI 1.12; SPI 0.00; PTHI 0.91; PTWI 1.16; PPI 1.82; LBI 1.78.

Description

( Fig. 9A, C ) Small (HW 0.74, WL 1.53).

Mandibles very short and reduced, masticatory margin with two teeth, one large apical and a minute second; clypeus moderately protruding; eyes large (OI 0.57) and protruding, midline of eyes situated well below midline of head, almost extending to clypeal margin; antennae 12-segmented; head much wider than long (CI 1.46); in full-face view ocellar triangle situated at posterior head margin and elevated with respect to rest of face; occipital carinae distinct.

Mesoscutum in dorsal view as wide as long (MSNI 1.12); scutellum in dorsal view broadly tapering from anterior to posterior end, dorsoposteriorly rounded; metanotum protruding from below scutellum; dorsal face of propodeum almost as long as posterior face; propodeal spines absent; petiole in dorsal view oval, laterally rounded, in lateral view anteriorly greatly tapering; subpetiolar process absent; postpetiole round, lacking median impression.

Head sculpture shiny to rugulose, clypeus shiny; mesoscutum with very fine longitudinal carinulae; otherwise sculpture more or less shiny to aciculate; scattered, short, erect pilosity and a few longer setae on face, mesoscutum, and scutellum; remaining pilosity as in queens. Color brown.

Distribution and biology

MADAGASCAR. Crematogaster degeeri occurs in montane rainforest, savannah, woodland and grassland habitats in central and south-central Madagascar at altitudes from 800 to 2650 m ( Fig. 9B ). This species occurs often in sympatry with C. mafybe sp. nov., and at some locations with C. sewelli . These ants are often found nesting on the ground under stones or in the soil, although a few records of arboreal twig collections also exist.

Comments

In the molecular analysis, Crematogaster degeeri was found to be not reciprocally monophyletic with respect to C. ramamy (see above and Fig. 1 ). Refer to comments under C. ramamy for further discussion.

Figures

Fig. 8. Crematogaster degeeri Forel, 1886, worker and queen. A-C. Worker (CASENT0118982). A. Full-face. B. Profile. C. Dorsal. D-F. Queen (CASENT0012763). D. Full-face. E. Dorsal F. Profile.

Fig. 9. Crematogaster degeeri Forel, 1886, male and distribution. A, C. (CASENT0127520). A. Fullface. C. Profile. B. Species distribution.

Fig. 5. Key to the species of the C. degeeri-assemblage (part II). A. Pronotum with sharp lateral margins [C. malahelo sp. nov., CASENT0317768]. B. Pronotum lacking sharp lateral margin [C. alafara sp. nov., CASENT0492837]. C. Mesonotum with posterolateral denticles [C. degeeri Forel, 1886, CASENT0071423]. D. Mesonotum without distinct posterolateral denticles [C. ramamy sp. nov., CASENT0317764]. E. Propodeum with distinct short dorsal face and transverse impression, sculpture carinulate [C. ramamy sp. nov., CASENT0317764]. F. Propodeum lacking distinct dorsal face and transverse impression, sculpture rugulose [C. dentata Dalla Torre, 1893 stat. nov., CASENT0138289].

Fig. 1. Mitochondrial phylogeny of species in the Crematogaster degeeri-assemblage. Results of Bayesian inference based on 592 bp of COI, summarized as a consensus tree in MrBayes. Support values in black represent posterior probabilities (pp), those in blue ML (Maximum Likelihood) bootstrap values>70, and those in red ML bootstrap values<70. Values pp <0.96 are not shown; nodes not present in the ML analysis are represented by a dash instead of a bootstrap value. The scale bar shows nucleotide changes per base pair. Long branches subtending the outgroup taxa C. madecassa Emery, 1895, C. ranavalonae Forel, 1887 and C. hova-complex have been shortened. Appended numbers on taxon labels represent CASENT#’s of respective voucher specimens.