Tanipone

Known only from Madagascar, Tanipone are terrestrial cerapachyine ants that are occasionally found on low vegetation.

Nomenclature

 *  TANIPONE [Cerapachyinae: Cerapachyini]
 * Tanipone Bolton & Fisher, 2012: 75. Type-species: Tanipone hirsuta, by original designation.

Worker
A Malagasy genus of predominantly terrestrial cerapachyine ants, but also quite frequently found on low vegetation. With the shared characters of Cerapachyini listed in the introduction and also with the following combination of characters. Two apomorphies of the genus are in italics.

1 Palp formula 6,4. Maxillary palps extremely long: with mouthparts retracted the apices of the maxillary palps, when extended back on underside of head, extend beyond the level of the posterior margin of the eye and usually approach the occipital foramen.

2 Antenna with 12 segments, tapering apically and not incrassate; apical antennomere subcylindrical and tapering apically, not swollen and bulbous, no broader than the preapical segment.

3 Scape short (SI 49–65), when laid straight back in full-face view the apex of the scape excedes the level of the anterior margin of the eye but never reaches the level of the posterior margin of the eye.

4 Eyes large (EL/HW 0.37–0.48), located slightly behind the midlength of the head.

5 Ocelli present.

6 Clypeus more or less flat between the slightly elevated frontal lobes; frontal carinae very short, constricted and terminating almost immediately behind the frontal lobes.

7 Parafrontal ridges short and indistinct, weakly developed.

8 Head capsule with a short, vertical posterior surface above the occipital foramen, that meets the vertex through a blunt angle; vertex behind ocelli usually with a very fine, low transverse ridge.

9 Head capsule, in ventral or ventrolateral view, with a carina that extends down the posterolateral margin and onto the ventral surface where it passes through a near right-angle and extends to the ventral midline.

10 Mesosoma dorsally without trace of the promesonotal suture; metanotal groove vestigial to absent.

11 Pronotum in dorsal view rounded anteriorly between anterior surface and dorsum, not transversely marginate nor carinate; propodeum marginate or carinate between dorsum and declivity, even if only weakly so.

12 Mesopleuron with a strongly developed transverse sulcus.

13 Mesotibia without spurs (a setiform vestige is usually visible).

14 Metatibia with a single, pectinate spur.

15 Metatibial gland present, its orifice usually small and indistinct.

16 Metabasitarsus ventrally without a longitudinal glandular groove.

17 Pretarsal claws of at least the metatarsus with a single, small, preapical tooth on the inner surface of each claw.

18 Propodeal lobe in profile small, rounded apically.

19 Propodeal spiracle orifice small, circular.

20 AII (petiole) not marginate laterally in dorsal view.

21 AIII not postpetiolate, in dorsal view more voluminous than AII but only a little smaller than AIV.

22 ''Tergite of AIII with a pair of subovate glandular patches on the posterior half. Posterior margin of segment with a transverse band of pale cuticle, or a pair of pale patches, that subtend the glands''.

23 Prora of AIII a small, simple, convex cuticular boss or prominence, not delimited by a sharp curved carina that separates the anterior face of the poststernite from the lateral and ventral surfaces.

24 Pretergite of AIV in dorsal view not strongly constricted with respect to posttergite of AIV.

25 Cinctus of AIV either with or without cross-ribs.

26 Pygidial denticles sparse, restricted to a short apical arc along a narrow prominence at the extreme apex of the sclerite.

Comments on worker characters

Numbers correspond to character numbers above.

1 Palp formula 6,4 has been confirmed by in situ counts of fully extended mouthparts of all species, and also by dissection of Tanipone hirsuta, Tanipone maculata, Tanipone pilosa, Tanipone varia and Tanipone zona. The extreme elongation of the palps, especially the maxillaries, is not matched in any other cerapachyine, or any other dorylomorph, genus.

9 The carina in Tanipone is very similar to that seen in Vicinopone, and quite different from the carina as developed in Simopone. In that genus the carina extends onto the ventral surface but terminates or fades out well before meeting the ventral midline.

13 As in Simopone, the mesotibial apex usually has one to several setae that are roughly aligned with the long axis of the tibia. In Tanipone one of these setae almost certainly represents the last vestige of a spur.

15 When a visible orifice of the metatibial gland is discernible, it generally appears as a slightly depressed, small, subovate patch or pore, located posterior to the small cuticular vesicle at the base of the spur and usually off the ventral midline of the metatibia. The orifice is variously developed in different species of the genus. In aglandula it is a shallow elongate depression; in aversa, Tanipone cognata, Tanipone pilosa, Tanipone scelesta, Tanipone subpilosa and Tanipone varia it forms a subcircular to subovate patch or pore; in Tanipone hirsuta there is no obvious pore, but a small patch of pale cuticle is present. In the two very closely related species Tanipone maculata and Tanipone zona, no orifice can usually be seen, but an inconspicuous minute pore occurs in some workers. Variation of this nature is not surprising and is replicated elsewhere. For instance, in the two closely related West African Cerapachys species, Cerapachys foreli (Santschi) and Cerapachys nkomoensis (Forel), the gland orifice is a shallow oval pore in the former, but an elongate deep slit, often filled with whitish flocculent material, in the latter.

17 Unlike in Simopone, the extra tooth on each pretarsal claw is usually not uniformly present on every leg in the various species of Tanipone. On the metatarsus the preapical teeth of the pretarsal claws are most commonly present; they are always conspicuous in Tanipone aglandula, Tanipone hirsuta and Tanipone pilosa, and small but usually distinct in Tanipone cognata and Tanipone maculata. However, in some species they may be minute and difficult to discern (Tanipone aversa), and sometimes appear to be absent (e.g. not discernible in some specimens of Tanipone scelesta and Tanipone zona, and many specimens of Tanipone varia). On the mesotibial claws a small extra tooth is uncommon; most specimens have the claws simple, although an extra tooth has been seen in some specimens of aglandula, hirsuta, Tanipone maculata and pilosa. Protibial claws are almost always simple; a small tooth has been clearly detected only in a couple of specimens of hirsuta.

20 Anterior surface of AII slopes posteriorly in profile. The anterior and dorsal surfaces, and the dorsal and posterior surfaces, are separated by blunt angles or weak transverse carinae; the posterior margin in dorsal view is usually shallowly concave medially. The side of AII tergite has a longitudinal carina above the level of the spiracle.

22 In a single species, aglandula, the glandular patches are not visible on the surface of AIII by light microscopy, but the characteristic pale area that subtends the glands and appears associated with them is strongly retained. Whether the glands remain present beneath the tergite, or whether they have atrophied and been entirely lost in this species, remains to be seen. Whichever, it is most parsimonious to assume apparent modification or loss of the paired gland in aglandula, rather than to assume its individual development in every other species of the genus. The pale band, or pair of pale spots, at the apex of tergite AIII is conspicuous in all species save for a few specimens of scelesta, where it may be very faint or even absent, but in these few specimens the glandular patches themselves remain conspicuous.

24 In dorsal view the maximum width of the pretergite of AIV is 0.76–0.89 × the maximum width of the posttergite of the segment. This is relatively much wider than in Simopone (0.52–0.69) and Vicinopone (0.62–0.64). The ratio has not yet been investigated in other cerapachyine genera.

25 When cross-ribs are present on the cinctus they are very short, indistinct, fine and crowded.

Queen
PUTATIVE ERGATOID GYNE

No standard alate/dealate queens with any trace of developed flight sclerites have been discovered for any species of Tanipone. However, in cognata, scelesta and maculata a few specimens (1, 1, and 2, respectively) are distinctly more densely sculptured. In particular, they possess a very conspicuous, fine, dense microreticulation between the punctures on the dorsal mesosoma. In scelesta and maculata, these specimens differ from their otherwise identical workers only in this feature: in maculata a graded increment of sculpture appears to link specimens with the weakest sculpture to those with the strongest. The specimen of cognata is a singleton which, disregarding the mesosomal sculpture, does not otherwise resemble any known worker. It may be that these more heavily sculptured forms represent a rare upper limit of worker sculptural variation within each species of the maculata group. Yet the possibility that they may represent separate species cannot be dismissed. However, it is suspected that these rare forms do not represent separate species or densely sculptured workers, but are in fact extreme ergatoid gynes; they therefore exhibit all the characters of the worker diagnosis at genus rank. Only dissection of the ovaries and spermathecae of these oddities will reveal the truth of the matter, but material suitable for such a detailed examination is not presently available.

Male
Males caught in association with workers are known only for Tanipone zona. In are many unassociated males retrieved from light traps, where they appear to be reasonably common. These have not been treated in detail as regards species-rank taxonomy, but have been utilised to make the diagnosis of this sex as complete as possible.

1 Palp formula 6,4; the maxillary palps, when laid back along the underside of the head, reach or very nearly reach the occipital foramen.

2 Mandibles triangular and edentate, masticatory margins meeting at full closure; masticatory margins straight to shallowly concave.

3 Antenna 13-segmented, filiform; funicular segments 3 to apex longer than broad; apical segment tapering apically and not swollen, slightly longer than funicular segment 12 but no broader.

4 Eyes large and very conspicuous.

5 Ocelli present.

6 Frontal lobes short and convergent posteriorly, not concealing the antennal sockets in full-face view; frontal carinae short or very short, abruptly terminated posteriorly.

7 Head capsule, in ventral or ventrolateral view, with a carina that extends down the posterolateral margin and onto the ventral surface, where it abruptly curves medially and extends to the ventral midline.

8 Pronotum visible anteriorly in dorsal view as a narrow collar in front of the mesoscutum.

9 Notauli absent.

10 Parapsidal grooves present but often feebly developed.

11 Propodeal lobes present and conspicuous.

12 Mesotibia without spurs (a setiform vestige is usually present).

13 Metatibia with a single, pectinate spur.

14 Pretarsal claws with or without a preapical small tooth.

15 Venation as discussed below.

16 Prora present as a small lobe or short transverse crest.

17 AIII not postpetiolate; in dorsal view AIV > AIII, the two broadly articulated; AIII > AII.

18 Glandular patches absent from tergite of AIII.

19 Pygidium with posterior margin not denticulate.

Comments on male characters

Numbers correspond to character numbers above.

1 The palp formula of 6,4 has been seen in every specimen examined in which the mouthparts were extended and can even be counted in many specimens in which the mouthparts are fully retracted. The maxillary palps are as disproportionately elongated as in the workers and ergatoids.

9 No traces of notauli remain on the mesosocutum, in marked contrast to Simopone males, where notauli are very strongly developed.

10 In the majority of specimens parapsidal grooves are present on each side of the mesoscutum as fine, faint impressions. In a few specimens they are extremely faint and not easy to see.

14 In a single unassociated male a small preapical tooth is present on the pretarsal claws of the mesotarsus and metatarsus but absent from the protarsus. In zona and other males examined a tiny preapical tooth is often apparent on the metatarsal claws but is sometimes absent. The claws of the mesotarsi are predominantly simple, with only a tiny or vestigial tooth in some; the protarsal claws always appear simple.

15 The most complete forewing venation is shown by an unassociated male from Morondava, in UCDC (P.S. Ward#11112-7), from a light trap. The pterostigma is large and pigmented; C is absent and R1•f3 is absent distal of the pterostigma; pigmented tubular veins are represented only by Sc+R, Sc+R1, Rs•f1, M+Cu, M•f1, cu-a, and A to just distal of cu-a. The remaining veins are depigmented but mostly tubular, the long veins tend to fade distally: Rs+M, M and Cu are distinct, but Rs•f2-3 is absent and Rs•f4-5 fades out just before reaching the margin. Crossveins cu-a (which always arises from M+Cu), 1m-cu and 2rs-m are present and easily visible, but 2r-rs is faint. Most specimens show reductions from this pattern, with various veins disappearing, but a large, pigmented pterostigma is always retained. In many specimens 2rs-m is lost, leaving a “stigmal vein” (= 2r-rs&Rs•f4-5) dependent from the pterostigma; but often this is very faint and may also be lost. In the most reduced forewings only a framework of weak veins in the proximal half of the wing membrane remains, consisting of Sc+R, Sc+R1, Rs•f1, M•f1, M+Cu and the basal portion of A.