Prenolepis jacobsoni Crawley, 1923

(Figs 83–85)

Prenolepis jacobsoni Crawley, 1923: 30 (w.). Neotype worker [designated here], INDONESIA: West Sumatra, Maninjau, 07– 09.viii.1985 (USNM: USNMENT00755101). This species was described by Crawley (1923) from a single worker specimen, but the type material is missing. In the interest of nomenclatural stability a neotype is designated. The neotype is from the original type locality.

Worker diagnosis. Small in overall size (TL: 2.42–2.64mm; Fig 20); obtusely angled propodeum with flat dorsal and posterior faces; petiole low in profile and elongate with a prominent anteroventral process (Fig 54).

Most similar species. P. darlena, P. fustinoda, P. jerdoni, P. subopaca

Morphology. Worker. Measurements (n=2): CMC: 10–14; EL: 0.21; EW: 0.17; HL: 0.61–0.66; HLA: 0.32– 0.34; HLP: 0.19; HW: 0.57–0.58; IOD: 0.44; LF1: 0.17; LF2: 0.11; LHT: 0.83–0.84; MMC: 2; MTW: 0.35–0.37; MW: 0.22; PDH: 0.26–0.27; PMC: 1–3; PrCL: 0.38–0.40; PrCW: 0.21; PrFL: 0.68–0.70; PrFW: 0.15–0.16; PTH: 0.21; PTL: 0.37–0.41; PTW: 0.19–0.22; PW: 0.43–0.44; SL: 0.86–0.92; TL: 2.42–2.64; WF1: 0.06; WF2: 0.05; WL: 0.88–0.89; BLI: 172–175; CI: 87–94; EPI: 172–175; FLI: 153; HTI: 145; PetHI: 79–81; PetWI: 53; PrCI: 52– 55; PrFI: 22; REL: 32–35; REL2: 37; REL3: 48–49; SI: 150–159.

Light to medium brown; cuticle of head, pronotum, mesopleuron, and gaster smooth and shiny; cuticle between metanotal spiracles rugoreticulate; very long, erect macrosetae on head and gaster; abundant decumbent setae on scapes and legs; sparse erect macrosetae on mesosoma; no erect macrosetae on the propodeum; head about as broad as long or slightly longer than broad and oval in shape with indistinct posterolateral corners and a convex posterior margin; compound eyes moderately large and convex, barely surpassing the lateral margins of the head in full-face view; torulae do not touch the posterior border of the clypeus; clypeus strongly medially convex and without prominent anterolateral lobes (Fig 43); mandibles with 6 teeth on the masticatory margin; ectal surface of mandibles smooth and shiny; in profile view, propodeum is obtusely angled with a flat dorsal face (Fig 20); petiole is narrow and elongate (PetWI <55) with a prominent anteroventral process (Fig 54); scale of petiole is low in profile with a rounded dorsal apex of the scale.

Notes. This species has a narrow and elongate petiole (PetWI <55) like P. darlena, P. fustinoda, P. jerdoni, and P. subopaca . In P. jacobsoni the petiole is distinct in that there is a prominent anteroventral process present and the scale has a unique shape (Fig 54). Prenolepis jacobsoni can also be distinguished by its smaller size, lighter color, and overall smooth cuticle.