Key to Cataulacus of the Malagasy Region

The key on this page is based on the key from Bolton's world revision of the genus: Bolton, B. 1974. A revision of the Palaeotropical arboreal ant genus Cataulacus F. Smith (Hymenoptera: Formicidae). Bulletin of the British Museum (Natural History) Entomology. 30:1-105.

A revised key to the Afrotropical species was published by Bolton in 1982 (Bolton, B. 1982. "Afrotropical species of the myrmicine ant genera Cardiocondyla, Leptothorax, Melissotarsus, Messor and Cataulacus (Formicidae)." Bulletin of the British Museum (Natural History) Entomology. 45:307-370). That key provided revisions that reflected revisionary changes of the African species but there were no changes to the Malagasy fauna.

Afrotropical species should be keyed out using this 1982 Key to Afrotropical Cataulacus Species.

The 1974 key to the Indo-Australian and Oriental species is found here: Key to Cataulacus of the Indo-Australian and Oriental Regions.

The 1974 key, given below, should be used for Malagasy species. There are now known to be a few undescribed species in the region that are not accounted for in this key.

Key to the Species of the Ethiopian and Malagasy Regions
Based on the worker caste. Due to sculptural variation intrudens is keyed out in two places. Couplets that terminate with a Malagasy species include a head and dorsal view image of the relevant species.

1

 * Propodeum completely unarmed, without spines or teeth; propodeal dorsum transversely rugulose. (Zaire) . . . . . Cataulacus inermis


 * Propodeum armed, usually with a pair of distinct spines, more rarely with a pair of short teeth; if the latter then the propodeal dorsum is not transversely rugulose . . . . . 2

2
return to couplet #1
 * First gastral tergite with a lateral margination or carina at least basally which is paralleled by a similar structure on the first sternite. Node of petiole transversely rectangular in dorsal view, strongly transversely rugose or sulcate . . . . . 3


 * First gastral tergite rarely with, usually without a lateral margination or carina basally, this structure never developed upon the sternite. Node of petiole usually not transversely rectangular in dorsal view, rarely transversely sculptured . . . . . 4

3
return to couplet #2
 * Sides of head behind eyes irregular, either denticulate, crenulate or otherwise jagged. Relatively broader-headed species, CI > 125, the head strongly broadened behind the eyes. Laterally projecting hairs on the sides of the head behind the eyes long and conspicuous. (West and Central Africa, Uganda, Zambia) . . . . . Cataulacus huberi


 * Sides of head behind eyes regular, smooth, neither denticulate nor crenulate. Relatively narrower-headed species, CI 120 or less, the head not strongly broadened behind the eyes. Laterally projecting hairs on the sides of the head behind the eyes minute and inconspicuous or completely absent. (West and Central Africa) . . . . . Cataulacus egenus

4
return to couplet #2
 * Petiole and postpetiole strongly transverse, much flattened dorsoventrally, without nodes; both very broadly and thickly V-shaped in dorsal view. Propodeal spines very small, inconspicuous, reduced to a pair of short or minute triangular teeth. (West Africa, Zaire) . . . . . Cataulacus mocquerysi


 * Petiole and postpetiole nodiform, not strongly transverse nor flattened, not broadly V-shaped in dorsal view. Propodeal spines well developed, conspicuous, not reduced to triangular teeth . . . . . 5

5
return to couplet #4
 * Occipital corners of head drawn out into a long, very broadly triangular point on each side. Sides of head behind eyes and lateral margins of alitrunk without denticles, the alitrunk laterally also without projecting lobes, teeth or prominences. Preocular tooth absent. Very large species, HW > 2.60 with relatively very small eyes, OI < 22. (Madagascar) . . . . . Cataulacus oberthueri


 * Occipital corners of head with a tooth, a denticle or unarmed, but not drawn out into a long, broadly triangular point. Sides of head behind eyes or margins of alitrunk usually denticulate, or the alitrunk laterally with projecting lobes, teeth or prominences. Preocular tooth usually present. Smaller species, HW < 2.60 with relatively larger eyes, OI > 22 . . . . . 6

6
return to couplet #5
 * In profile the dorsal surfaces of the head behind the clypeus and the dorsal alitrunk without projecting erect hairs (a few may be present on the margins and around the eyes) or with sparse, strongly adpressed hairs . . . . . 7


 * In profile either the dorsal surfaces of the head behind the clypeus or the dorsal alitrunk or both with projecting, erect hairs, often numerous but sometimes sparse or short and inconspicuous; never strongly adpressed . . . . . 14

7
return to couplet #6
 * Mesonotum regularly longitudinally striate, the propodeal dorsum regularly transversely striate. (Madagascar: Ste. Marie Is.) . . . . . Cataulacus wasmanni


 * Sculpturation of mesonotum and propodeal dorsum either not striate or regularly longitudinally sculptured throughout, the direction of the sculpturation not differing on mesonotum and propodeal dorsum . . . . . 8

8
return to couplet #7
 * Dorsum of alitrunk sculptured with regular, parallel, longitudinal sulci throughout . . . . . 9


 * Dorsum of alitrunk finely and densely reticulate-punctate with fine, longitudinal rugulae or rugoreticulum . . . . . 10

9
return to couplet #8
 * Dorsum of head evenly longitudinally sulcate, as the alitrunk. Dorsum of alitrunk without short, strongly adpressed hairs.  Larger species, HL > 1.10, PW > 0.90, with relatively broader head and smaller eyes, CI 100 or more, OI < 40. (Madagascar) . . . . . Cataulacus regularis


 * Dorsum of head finely reticulate-punctate with an overlying rugoreticulum, contrasting to the sulcate alitrunk. Dorsum of alitrunk with a few scattered, small, strongly curved, adpressed hairs, best seen upon the propodeal dorsum. Smaller species, HL < 0.95, PW < 0.75 with relatively narrower head and larger eyes, CI < 95, OI > 50. (Ghana) . . . . . Cataulacus adpressus

10
return to couplet #8
 * With the head in full-face view the lateral margins between the eyes and the occipital corners equipped with a continuous row of short, freely projecting hairs . . . . . 11


 * With the head in full-face view the lateral margins between the eyes and the occipital corners without a row of short, projecting hairs. If one or two hairs are present they are minute and do not project freely beyond the margins. (West and Central Africa) . . . . . Cataulacus tardus

11
return to couplet #10
 * Dorsum of petiole transversely rugose, the first gastral tergite very finely and densely longitudinally arched-rugulose, the rugulae converging upon the midline at least anteriorly, and often subcircular in organization. (West and Central Africa, Uganda) . . . . . Cataulacus kohli


 * Dorsum of petiole not transversely rugose; the first gastral tergite predominantly finely and densely reticulate-punctate. A few basigastric rugulae may be present as may a few rugulae upon the disc, but the sculpturation not as above . . . . . 12

12
return to couplet #11
 * Postpetiole divided into two lobes by a strong, median longitudinal cleft dorsally. Lateral pronotal margins without differentiated, projecting teeth. (Cameroun, Zaire) . . . . . Cataulacus lobatus


 * Postpetiole not divided into two lobes by a median longitudinal cleft dorsally. Lateral pronotal margins with one or two differentiated projecting teeth . . . . . 13

13
return to couplet #12
 * Lateral pronotal margins each with two teeth. Propodeal spines relatively long, about as long as the petiole. (Central Africa, Kenya) . . . . . Cataulacus pullus


 * Lateral pronotal margins each with a single tooth situated close to the acute humeral angles. Propodeal spines relatively short, shorter than the length of the petiole. (Zaire) . . . . . Cataulacus theobromicola

14
return to couplet #6
 * Head exceptionally long, distinctly much longer than broad, CI < 80. (Madagascar) . . . . . Cataulacus tenuis


 * Head not as remarkable elongate, CI > 85, often CI > 100 . . . . . 15

15
return to couplet #14
 * Head, alitrunk and pedicel dorsally with strong, undulate, longitudinal sulci, finer upon the head than on the alitrunk. A few short, clavate hairs present on the dorsal alitrunk. (Madagascar) . . . . . Cataulacus porcatus


 * Sculpturation not as above, usually rugose or reticulate-rugose with reticulate-punctate interspaces. If the dorsal alitrunk is sulcate then either the head is differently sculptured or the alitrunk hairs are simple . . . . . 16

16
return to couplet #15
 * At least the hairs on the clypeus strongly clavate, spatulate, stalked-suborbicular or otherwise bizarre, usually also on the remainder of the cephalic dorsum. In the majority of cases the apex of each hair is strongly swollen whilst the stem is narrow. Eyes relatively large, OI > 48 . . . . . 17


 * All hairs on the clypeus and the remainder of the cephalic dorsum simple, usually short, stout and blunt but sometimes minute, sometimes very long and curved; rarely are they gradually increased in thickness from base to apex. If the last then the eyes are relatively smaller, OI < 47 . . . . . 18

17
return to couplet #16
 * Lateral pronotal margins with a tooth at the humeral angle and another at the junction of pro- and mesonotum; the margin between these two teeth without denticles or projecting hairs, smooth and very shallowly concave. (Nigeria, Zaire) . . . . . Cataulacus vorticus


 * Lateral pronotal margins with a row of small or minute denticles between the humeral angle and the tooth at the promesonotal junction; and with numerous projecting hairs. (Widespread in Africa) . . . . . Cataulacus brevisetosus

18
return to couplet #17
 * In dorsal view the posterolateral portion of the pronotal margin produced into a spine or triangular prominence. Head relatively broad or very broad, the eyes small, CI > 112, OI < 30 . . . . . 19


 * In dorsal view the posterolateral portion of the pronotal margin not produced as above but usually armed with a short tooth or denticle. When a short tooth is present in this position it is usually comparable in size to others upon the pronotal margin. Head relatively narrow, the eyes large, CI 110 or less, OI > 32 . . . . . 20

19
return to couplet #18
 * Sculpturation of dorsal alitrunk a very distinct rugoreticulum with reticulate-punctate interspaces. Lateral margins of mesonotum usually with one or more denticles. (West and Central Africa) . . . . . Cataulacus erinaceus


 * Sculpturation of dorsal alitrunk variable in intensity but consisting essentially of a longitudinal rugation or sulcation which may be irregular or sinuate. Lateral margins of mesonotum usually without denticles.  (West and Central Africa) . . . . . Cataulacus guineensis

20
return to couplet #18
 * Erect hairs on dorsal surfaces of head, alitrunk, pedicel and gaster abundant, dense, very long, narrow and fine, often curved or even sinuate . . . . . 21


 * Erect hairs on dorsal surfaces of head, alitrunk, pedicel and gaster relatively sparse, short, broad, blunt and coarse, never sinuate . . . . . 22

21
return to couplet #20
 * Propodeal dorsum longitudinally rugulose or rugose. Larger species HL > 0.90, HW > 0.85 with a relatively long alitrunk, AL 1.00 or more. (Ghana, Angola) . . . . . Cataulacus elongatus


 * Propodeal dorsum transversely rugulose. Smaller species, HL < 0.90, HW < 0.85, with a relatively short, broad alitrunk, AL ca 0.80 (Zaire) . . . . . Cataulacus pilosus

22
return to couplet #21
 * First gastral tergite coarsely longitudinally rugose on the disc in the anterior one-third of its length; posteriorly the rugae on the disc running transversely. (Madagascar: Grand Comoro Is.) . . . . . Cataulacus voeltzkowi


 * First gastral tergite variously sculptured but never with longitudinal rugae anteriorly and transverse rugae posteriorly upon the disc . . . . . 23

23
return to couplet #22
 * Posterior one-quarter of first gastral tergite coarsely longitudinally rugose, rugulose or striate; this sculpturation always distinct, usually extending to the apex of the tergite, sometimes extending the length of the segment . . . . . 24


 * Posterior one-quarter of first gastral tergite reticulate-punctate or finely superficially sculptured and shining; a few fine, scattered longitudinal rugulae formed by fusion of the margins of aligned punctures may be present . . . . . 27

24
return to couplet #23
 * Dorsal alitrunk and first gastral tergite finely and regularly longitudinally sulcate-rugose throughout their lengths. Smaller species, HW < 0.90 with relatively large eyes, OI > 49. (Zaire, Kenya) . . . . . Cataulacus striativentris


 * Dorsal alitrunk reticulate-rugose, reticulate-punctate or both. First gastral tergite not regularly sulcate-rugose throughout its length, usually with puncturation, at least on median portion of disc. Larger species, HW > 0.95 with relatively smaller eyes, OI < 47 . . . . . 25

25
return to couplet #24
 * Mesonotum reticulate-punctate. First gastral tergite densely and deeply longitudinally striate on the posterior quarter, the preceding half-length of the tergite finely reticulate-punctate.  CI 98 or less. (Madagascar) . . . . . Cataulacus ebrardi


 * Mesonotum with a rugoreticulum overlying the reticulate-puncturation, the former may be very coarse, masking the latter which is usually best developed on the centre of the disc. First gastral tergite sometimes striate or rugose throughout its length. CI 98 or more (usually > 100) . . . . . 26

26
return to couplet #25
 * Dorsal surfaces of head and alitrunk with numerous conspicuous, relatively long hairs. Sculpturation of dorsal alitrunk a fine and spaced rugoreticulum overlying a fine, dense reticulate-puncturation. Eyes relatively somewhat larger, OI 41 or more. (Mozambique, South Africa) . . . . . Cataulacus wissmannii


 * Dorsal surfaces of head and alitrunk with relatively few inconspicuous short hairs. Sculpturation of dorsal alitrunk variable; usually a coarse, dense rugulation or rugoreticulum but the rugae may be reduced. Very rarely the mesonotum shagreened, with large foveolae. Eyes relatively somewhat smaller, OI 34 to 40. (South and East Africa, Madagascar) . . . . . Cataulacus intrudens

27
return to couplet #23
 * Occiput with a distinct transverse groove above the foramen. In profile the mesonotum separated from the propodeal dorsum by a short but distinct step; propodeal dorsum approximately flat and on a lower level than the mesonotum. (Uganda) . . . . . Cataulacus impressus


 * Occiput without a transverse groove above the foramen. In profile the mesonotum forming a more or less continuous and uninterrupted convex surface with the propodeal dorsum . . . . . 28

28
return to couplet #27
 * Tooth on mesokatepisternum large, long and acute, projecting anterolaterally and clearly visible in dorsal view, projecting beyond the marginations of the mesonotum . . . . . 29


 * Tooth on mesokatepisternum small and short, usually a mere tubercle or acute angle; in dorsal view this tooth not or only very little visible . . . . . 30

29
return to couplet #28
 * Vertex of head meeting occiput in an acute angle; the first gastral tergite very finely reticulate or reticulate-punctate. Larger species, HW > 0.95, PW > 0.75 with relatively small eyes, OI < 45 and the head as broad as or broader than long, CI 100 or more. (South Africa) . . . . . Cataulacus micans


 * Vertex of head running into occiput through a continuous curve, the two surfaces not separated by an acute angle. First gastral tergite coarsely reticulate-punctate. Smaller species, HW < 0.85, PW < 0.70 with relatively large eyes, OI > 50 and the head longer than broad, CI < 95. (Dahomey) . . . . . Cataulacus difficilis

30
return to couplet #28
 * Subpetiolar process complex, anteroventrally with a prominent, broadly rounded angle and posteroventrally with an extended heel or spur. Postpetiole with a strongly developed, simple, digitiform ventral process . . . . . 31


 * Subpetiolar process simple, a rectangular or subrectangular lobe without the above configuration or with an acute angle or small tooth posteroventrally; if the latter then the postpetiole without a strongly developed digitiform ventral process . . . . . 32

31
return to couplet #30
 * Larger species, HL > 1.00, HW > 1.00, PW > 1.00 with relatively broader head and smaller eyes, CI > 1000, OI < 45. Propodeal spines very strongly developed, long, stout, acute and divergent. Posterolateral portion of pronotal margination expanded into a low, broadly triangular extension with denticulate borders (Zaire) . . . . . Cataulacus greggi


 * Smaller species, HL < 1.00, HW < 0.95, PW < 1.00 with relatively narrower head and larger eyes, CI < 100, OI < 50. Propodeal spines acute but short and poorly developed. Posterolateral portion of pronotal margination not expanded as above. (West and Central Africa, Kenya) . . . . . Cataulacus weissi

32
return to couplet #30
 * Smaller species, HW < 1.10, PW < 0.90 . . . . . 33


 * Larger species, HW > 1.10, PW > 0.90 . . . . . 34

33
return to couplet #32
 * Head longer than broad, CI < 100, with slightly larger eyes, or 41 or more. Lateral pronotal margins with a regular row of denticles, the margination itself not strongly expanded. First gastral tergite with a few longitudinal rugulae in the middle of the disc. (Widespread in Africa) . . . . . Cataulacus pygmaeus


 * Head broader than long, CI > 105, with slightly smaller eyes, or 41 or less. Lateral pronotal margins with a few irregular, rounded, tuberculiform teeth, the margination itself strongly expanded. First gastral tergite reticulate-punctate in the middle of the disc, without rugulae. (South Africa) . . . . . Cataulacus fricatidorsus

34
return to couplet #32
 * Short erect hairs thickly abundant on all dorsal surfaces, especially conspicuous upon the head, where they are very dense. Head relatively somewhat narrower, CI 102 or less, the eyes slightly larger, OI 40 or more. (Zaire) . . . . . Cataulacus bequaerti


 * Short erect hairs very sparse and scattered, often virtually absent from the dorsal head and alitrunk. Those present on the dorsal head, pronotum and mesonotum, especially the head, are very short and inconspicuous. Head relatively somewhat broader, CI 103 or more, eyes slightly smaller, or 40 or less. (South and East Africa, Madagascar) . . . . . Cataulacus intrudens (part)