Vicinopone

A monotypic African genus, the arboreal Vicinopone conciliatrix is known from relatively few collections.

Identification
Bolton and Fisher (2012) - In major details of morphology, striking contrasts between Vicinopone and all species of Simopone include the following (the state considered apomorphic is italicised).

1 Palp formula is 3,2 in Vicinopone, as opposed to 6,4 or more rarely 5,3 in Simopone.

2 Antennae have 12 antennomeres in Vicinopone, as opposed to 11 antennomeres in Simopone.

3 Scape, when laid straight back, reaches the posterior margin of the eye in Vicinopone, as opposed to the anterior margin of the eye in Simopone (SI 57–67 in Vicinopone, SI 33–56 in Simopone).

4 Ocelli are absent in Vicinopone, as opposed to present in Simopone.

5 Eyes are shifted very far forward in Vicinopone, as opposed to being near or behind the midlength in Simopone (EP 0.32–0.41 in Vicinopone, EP 0.68–1.91 in Simopone).

6 A differentiated posterior (occipital) surface to the head occurs in Vicinopone, as opposed to the lack of such a surface in Simopone.

7 Pre-occipital carina (that extends down the posterolateral margin of the head and onto the ventral surface) runs right across the ventral surface to intersect the ventral midline in Vicinopone, as opposed to the carina terminating well before it approaches the ventral midline in Simopone.

8 Metabasitarsus lacks a ventral glandular groove in Vicinopone, as opposed to the universal presence of such a groove in Simopone.

9 AII (petiole) tergite in dorsal view is elongate and barrel-shaped in Vicinopone, as opposed to flattened and laterally marginate in Simopone (AIIW/AIIL 0.68–0.75 in Vicinopone, AIIW/AIIL 0.79–1.30 in Simopone). 10 Cinctus of AIV is cross-ribbed in Vicinopone, as opposed to smooth in Simopone.

Distribution
Known from Democratic Republic of Congo, Gabon, Ghana, Tanzania and Uganda.

Biology
Bolton & Fisher (2012) - The only species of the genus is arboreal. Its rarity in collections may be a reflection of its actual abundance across its wide range but more likely than not it is completely arboreal hence the species, (and as the sole member of the Vicinopone, the genus) is not commonly encountered. The only known queens are two dealates collected from the same nest, suggesting polygyny. Workers are variable in size with larger workers having larger eyes.

Borowiec (2016) - Little is known of the species’ habits, but the two known nest samples have been taken from dead twigs on trees, suggesting that this is an obligatory arboreal nester. Two dealate gynes were collected with the type nest series (Brown 1975), suggesting that the ant may be polygynous. Brood production is not synchronized, as larvae and pupae of various stages were present in the nests at times of collection.

Nomenclature

 *  VICINOPONE  [Cerapachyinae: Cerapachyini]
 * Vicinopone Bolton & Fisher, 2012: 72. Type-species: Simopone conciliatrix, by original designation.

Worker
Shared characters of the genera Simopone, Vicinopone and Tanipone - As well as the 20 features that are exhibited by all members of Cerapachyini these three genera share the following suite of seven characters in the worker caste. None of the characters is claimed as synapomorphic for the three, or for any two of the three.

1 Pretarsal claws with a single preapical tooth, at least on the metatarsus.

2 Mesotibial spurs absent (at most a setiform vestige may remain that cannot be distinguished by light microscopy from other setae at the tibial apex).

3 Metatibial spur single, pectinate.

4 Eyes present and conspicuous, always large (EL/HW 0.30–0.53).

5 Apical antennomere subcylindrical, not inflated and bulbous.

6 Ventrolateral margin of head without a continuous longitudinal carina that commences close to anterior margin below the mandible and extends the entire length of the head to the posterior margin (a carina is present posterolaterally that usually extends onto the ventral surface).

7 Frontal lobes widely separated by the relatively broad clypeus; frontal lobes not or only slightly elevated laterally on each side of the clypeus (never closely approximated and vertical).

A monotypic Afrotropical genus of arboreal cerapachyine ants, with size-variable workers. With the shared characters of Cerapachyini listed in the introduction and also with the following combination of characters. An undoubted apomorphy of the genus is in italics.

1 Palp formula 3,2 (by dissection). Maxillary palp very short: with mouthparts retracted the apex of the maxillary palp, when extended back on underside of head, does not reach the posterior margin of the buccal cavity.

2 Antenna with 12 segments, gradually incrassate apically; apical antennomere large but subcylindrical, not swollen and bulbous.

3 Scape short (SI 56–67), when laid straight back in full-face view reaching the level of the posterior margin of the eye.

4 Eyes large (EL/HW 0.31–0.45), located very far forward on the head so that the posterior eye margin is in front of the midlength of the head.

5 Ocelli absent.

6 Clypeus more or less flat between the elevated frontal lobes; frontal carinae short, extending back to level of anterior margins of eyes only because the eyes are located so far forward.

7 Parafrontal ridges present but short and weak because of proximity of eye to front of head.

8 Head capsule with a short, vertical posterior surface above the occipital foramen; this surface separated from the vertex by a low, arched, transverse carina.

9 Head capsule, in ventral or ventrolateral view, with a carina that extends down the posterolateral margin and onto the ventral surface, which it crosses to meet its opposite number at the ventral midline; this carina is anterior to, and separate from, that which borders the occipital foramen.

10 Mesosoma dorsally with very feeble, shallow transverse concavities that represent the last vestiges of the promesonotal suture and metanotal groove; in some both are functionally absent. Dorsum and declivity of propodeum separated by a carina.

11 Mesopleuron without a strongly developed transverse sulcus; a vestige may remain in large workers.

12 Mesotibia without spurs.

13 Metatibia with a single, pectinate spur.

14 Metatibial gland absent (at least no external orifice or indication is present).

15 Metabasitarsus ventrally without a longitudinal glandular groove.

16 Pretarsal claws each with a single, small, preapical tooth on its inner surface.

17 Propodeal lobe in profile large and broad-based, rounded apically, continuous above with a narrow lamella that ascends the margin of the propodeal declivity.

18 AII (petiole) elongate, barrel-shaped, not marginate laterally and with a transverse carina that separates anterior and dorsal surfaces but without a similar carina posteriorly; the dorsum curves evenly down to the posterior foramen. Side of AII with a weak, oblique longitudinal carina above the level of the spiracle.

19 AIII postpetiolate, more voluminous than AII but the same length in dorsal view. AIII distinctly smaller than AIV.

20 Prora of AIII merely a curved carina that separates the anterior face of the poststernite from the lateral and ventral surfaces.

21 Pretergite of AIV in dorsal view strongly constricted with respect to posttergite of AIV.

22 Cinctus of AIV cross-ribbed.

23 Tergite of AIV without a pair of slightly depressed, subovate glandular patches on the posterior half.

24 Pygidium with its apical margin evenly curved and equipped with a continuous row of minute denticles that are all approximately equal in size.

Borowiec (2016) - Head: Antennae with 12 segments. Apical antennal segment moderately enlarged, broader than and about equal in length to two preceding segments combined. Clypeus without cuticular apron. Lateroclypeal teeth absent. Parafrontal ridges reduced. Torulo-posttorular complex vertical. Antennal scrobes absent. Labrum with median notch or concavity. Proximal face of stipes not projecting beyond inner margin of sclerite, prementum exposed when mouthparts fully closed. Maxillary palps 3-segmented. Labial palps 2-segmented. Mandibles triangular, edentate. Eyes present, composed of more than 20 ommatidia. Ocelli absent. Head capsule without differentiated vertical posterior surface above occipital foramen. Ventrolateral margins of head without lamella or ridge extending towards mandibles and beyond carina surrounding occipital foramen. Posterior head corners dorsolaterally immarginate. Carina surrounding occipital foramen ventrally present. Mesosoma: Pronotal flange separated from collar by distinct ridge. Promesonotal connection with suture completely fused. Pronotomesopleural suture visible, unfused partway to notal surface. Mesometapleural groove weakly impressed. Transverse groove dividing mesopleuron absent. Pleural endophragmal pit concavity present. Mesosoma dorsolaterally immarginate. Metanotal depression or groove on mesosoma absent. Propodeal spiracle situated low on sclerite. Propodeal declivity with distinct dorsal edge or margin and rectangular in posterior view. Metapleural gland with bulla visible through cuticle. Propodeal lobes present, well developed. Metasoma: Petiole anterodorsally marginate, dorsolaterally immarginate, and laterally above spiracle marginate. Helcium in relation to tergosternal suture placed at posttergite and axial. Prora forming a U-shaped margin with median ridge. Spiracle openings of abdominal segments IV–VI circular. Abdominal segment III anterodorsally immarginate and dorsolaterally immarginate. Abdominal segment III more than half size of succeeding segment IV, which is weakly constricted at presegmental portion (uninodal waist). Girdling constriction of segment IV present, i.e. pre- and postsclerites distinct. Cinctus of abdominal segment IV gutter-like and cross-ribbed. Abdominal segment IV not conspicuously largest segment. Abdominal tergite IV not folding over sternite, and anterior portions of sternite and tergite equally well visible in lateral view. Girdling constriction between pre- and posttergites of abdominal segments V and VI absent. Girdling constriction between pre- and poststernites of abdominal segments V and VI absent. Pygidium large, with impressed medial field, armed with modified setae. Hypopygium unarmed. Legs: Mid tibia without spurs. Hind tibia with single pectinate spur. Hind basitarsus not widening distally, circular in cross-section. Posterior flange of hind coxa not produced as raised lamella. Metatibial gland absent. Metabasitarsal gland absent. Hind pretarsal claws each armed with a tooth. Polymorphism: Monomorphic.

Queen
The queen is worker-like except that ocelli are present and the mesosoma has a full complement of flight sclerites. Therefore all the worker characters listed above, except for numbers 5 and 10, occur here. Venation unknown as the two queen specimens are dealate and were captured in a single nest, which implies that the species is probably polygynous.

Larva
Cocoons absent.