Corresponding author: Cong Liu (
Academic editor: M. Ohl
In this study we present a taxonomic update for the Oceanian
Liu C, Fischer G, Economo EP (2015) A rare ant on Samoa: first record of the cryptic subfamily Proceratiinae (Hymenoptera, Formicidae) and description of a new
According to
In the Oceanian region, nine species are presently known, eight of them recognized by
In the present publication,
The collection abbreviation follows
Osaka Museum of Natural History (
The holotype of the new species was collected during an inventory of the ant fauna of Samoa in 2015 by C. Liu and E.M. Sarnat. Morphological observations and measurements were performed with a Leica M165 C stereomicroscope equipped with an orthogonal pair of micrometres at a magnification of 100×. Measurements were recorded in millimetres to three decimal places and rounded to two decimal places for presentation. The measurements and indices used in this study follow
Eye length: maximum length of eye measured in oblique lateral view
Head length: maximum measurable distance from the mid-point of the anterior clypeal margin to the mid-point of the posterior margin of head, measured in full-face view. Impressions on anterior clypeal margin and posterior head margin reduce head length
Head length with mandibles: maximum head length in full-face view including closed mandible
Head length: Maximum head width directly behind the eyes, measured in full-face view
Hind femur length: maximum length of hind femur measured along its external face
Hind tibia length: maximum length of hind tibia measured along its external face
Hind basitarsus length: maximum length of hind basitarsus measured along its external face
Abdominal tergum III length: maximum length of abdominal tergum III (= length of segment III) in lateral view
Abdominal sternum IV length: maximum length of abdominal sternum IV following
Abdominal tergum IV length: maximum length of abdominal tergum IV following
Petiolar length: maximum length of the petiole in dorsal view including its anterior prolongation
Petiolar width: maximum width of petiole in dorsal view
Scape length: maximum length of scape shaft excluding basal condyle
Total body length: combined length of HLM + WL + PeL + LT3 + LT4
Weber’s length: diagonal length of mesosoma in lateral view from the anterior-most point of pronotal slope (excluding neck) to posterovental margin of propodeal lamella or lobe
Cephalic index: HW / HL × 100
Ocular index: EL / HW × 100
Scape index: SL / HL × 100
Dorsal petiole index: PeW / PeL × 100
Abdominal segment index: LT4 / LT3 × 100
Gastral reflexion index: LS4 / LT4
1 | Dorsal face of petiole node sub-rectangular, almost as wide as long ( |
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– | Dorsal face of petiole node narrow and transversally compressed, distinctly wider than long ( |
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2 | Subpetiolar process reduced and rounded without any distinct projections (Fig. |
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– | Subpetiolar process not reduced and rounded, either with spiniform or subtriangular / subrectangular lamellate projections (Fig. |
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3 | Petiole shape in profile squamiform, dorsally distinctly narrower than at the base and anterior face oblique (Fig. |
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– | Petiole shape in profile flattened subrectangular, at apex not distinctly narrower than at the base and anterior face vertical or subvertical (Fig. |
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4 | Subpetiolar process spiniform (Fiji) (Fig. |
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– | Subpetiolar process lamellate, subtriangular (Fiji) (Fig. |
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5 | Frontal lobes very small, each lobes’ surface area covering less than clypeal area in between frontal lobes (New Caledonia) (Fig. |
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– | Frontal lobes larger than clypeal area between frontal lobes (Fig. |
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6 | Larger species ( |
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– | Distinctly smaller species ( |
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Petiole and subpetiolar process in profile view.
Head in full-face view.
Body in profile view.
In full-face view, head subrectangular, longer than wide (
Mesosoma in profile convex, almost as long as maximum head length including mandibles. Lower mesopleuron with well impressed sutures, propodeum without posterior teeth, propodeal lobes small, reduced and blunt, posterior declivity relatively steep, in posterolateral and posterodorsal view separated from lateral propodeum by a distinct margin, propodeal spiracle circular and facing posterior end of mesosoma, situated slightly above mid height. Front and hind tibia with pectinate spur present, both without calcar of strigil, mesotibial spur absent, pretarsal claws simple, arolia absent. Petiole node in profile about as high as long, anterior face almost vertical, the dorsum almost flat, anteriorly and posteriorly weakly rounded, in dorsal view subrectangular with convex sides and slightly wider than long (DPeL 128), ventral process a small, blunt tooth.
Abdominal segment III in dorsal view anteriorly wider than petiole, posteriorly diverging, in profile abdominal sternite III anterolaterally with small, angulate anterior projection on either side of shallow median depression. Constriction between abdominal segments III and IV distinctly impressed. Abdominal segment IV strongly recurved (
Whole body in profile and in dorsal view covered with uniform dense layer of short, decumbent hairs, longer erect hairs completely absent.
Sculpture on mandibles irregularly punctate, on remainder of body very densely punctate, except for small smooth and shiny spot posterior of frontal lobes. Punctation also less strongly developed on abdominal segment IV, tergum IV appearing more shiny.
Body color dark red, legs and flagella of lighter, reddish brown coloration.
At present, the new species is only known from Savai island in Samoa, and is likely endemic to Samoa. The type locality is a montane rainforest on Mt. Silisili, situated at an elevation of 1200m. Only one single worker of the new species was collected through leaf litter extraction. The genus
The identification of
Fa’fetai lava to the Samoa government and kind people of Aopo community for allowing specimen collection and exportation. We thank Eli Sarnat for organizing and leading this ant survey. We thank Akanisi Caginitoba, Fialelei Enoka, Va’atele Anoifale Mulipola for the help with collection. We are also thankful to James Atherton for his help in the field.
We thank Michael Ohl, Marek Borowiec, and Brian Fisher for editing and reviewing the manuscript. The authors acknowledge the support of OIST and an NSF grant to EPE (NSF DEB-1145989).