Nylanderia silvula LaPolla and Fisher

Lapolla, John S., Hawkes, Peter G. & Fisher, Brian L., 2011, Monograph of Nylanderia (Hymenoptera: Formicidae) of the World, Part I: Nylanderia in the Afrotropics, Zootaxa 3110, pp. 10-36 : 23-24

Nylanderia silvula LaPolla and Fisher , sp. nov.

( Figs. 49–51 , 84 [worker]; 52–54 [queen]; 55–57, 101–103 [male])

Holotype worker, KENYA: Kakamega District, Kakamega Forest, Isecheno; 0.02° N, 34.97° E, 1800 m, 16 Oct 1999 (coll. R.R. Snelling) ( LACM); 13 paratype workers, 1 paratype male, same label data as holotype ( LACM, USNM).

Worker diagnosis: Large species (TL ≥ 2.8), with shining reddish-brown cuticle.

Compare with: This species is unique in its overall appearance.

WORKER. Measurements (n = 8): TL: 2.8–3.3; HW: 0.63–0.73; HL: 0.76–0.813; EL: 0.18–0.21; SL: 0.95– 1.04; PW: 0.45–0.51; WL: 0.976–1.12; GL: 1.04–1.35

Indices: CI: 84–90; REL: 22–26; SI: 142–151

Overall dark reddish-brown, with slightly lighter mandibles and antennae; trochanters, mesocoxae, and metacoxae yellowish to whitish; cuticle shining, with head, mesonotum (extending to mesopleuron), metanotal area, and propodeum rugulose. Posterior margin of head with rounded posterolateral corners, slightly emarginate medially. Scapes surpass posterior margin by about length of the first 3–3.5 funicular segments; scapes extremely setose, with erect macrosetae of varying lengths and a layer of decumbent pubescence (SMC = 45–60). Mesosoma with erect setae of varying lengths (PMC = 3–7; MMC = 2–4); in profile, pronotum elongate, with a linear rise towards mesonotum; metanotal area elongate; dorsal face of propodeum dome-like, slightly higher to even with the mesonotum; dorsal face and declivitous face about the same length; propodeum with scattered short appressed to decumbent pubescence. Gaster shining, with abundant erect macrosetae.

QUEEN. Measurements (n = 1): TL: 5.1; HW: 1.0; HL: 0.99; EL: 0.34; SL: 1.2; PW: 1.3; WL: 1.7; GL: 2.4 Indices: CI: 101; REL: 51; SI: 115

As in worker, with modifications expected for caste; darker reddish-brown than worker. Body shining with pubescence concentrated on dorsum; eyes large (taking up more than half of lateral margin), strongly convex; (PMC = 1); (MMC = 3).

MALE. Measurements (n = 3): TL: 2.9–3.0; HW: 0.68–0.72; HL: 0.64–0.66; EL: 0.32–0.33; SL: 0.87–0.95; PW: 0.78–0.82; WL: 1.0–1.3; GL: 1.1–1.2

Indices: CI: 105–111; REL: 126–138; SI: 17–19

Overall dark reddish-brown, with lighter brown funiculi, mandibles, and anterior clypeus; mesocoxae, metacoxae, mesotrochanter, metatrochanter, and tarsi white to very light yellow, with yellow protrochanter and joints of legs; cuticle smooth and shining, and covered with a dense pubescence except along mesopleuron and propodeum. Head with largely suberect macrosetae and a dense layer of pubescence. Compound eyes large (taking up most of lateral margin), ocelli large and raised. Scapes surpass posterior margin by about length of first 3–4 funicular segments; scapes with scatted erect macrosetae (SMC = 10–16) and dense layer of pubescence. Mandibular masticatory margin with prominent apical tooth and a smaller subapical tooth; basal margin rounded, but distinct. Mesosoma with dense pubescence and scattered erect setae (PMC = 0; MMC = 7–10) dorsally; declivity below level of mesonotum, smooth and shining; gaster with dense pubescence and scattered, erect macrosetae of varying heights. Genitalia (figs. 101–103): parameres roughly triangular in lateral view curving dorsally; dorsal margin of parameres directed outward from penis valves; cuspi elongated, apices rounded with peg-like teeth on ental surface where they meet digit; digiti apices broad; peg-like teeth at apices dorsally, ventrally coming to a narrow point that curves towards parameres.

Etymology. The specific epithet silvula (L. = forest) is in reference to the type locality of this species in the Kakamega Forest, one of the last remnants of indigenous forest in the region.

Non-type material examined. KENYA: Kakamega District; Kakamega Forest: Isecheno; 0.02° N, 34.97° E; 1800 m; 17 Oct 1999 (coll. R.R. Snelling); Kakamega District; Kakamega Forest: Isecheno; 0.02° N, 34.97° E; 1800 m; 21 April 2001

Notes. In addition to being one of the largest Afrotropical Nylanderia , the cuticular coloration of this species is unique. Interestingly, despite the difference (such as in color, overall size, shape of propodeum, etc.) in the appearance of the workers, the male digiti and cuspi are similar to those of N. boltoni , N. lepida , and N. natalensis .

Figures

FIGURES 46 – 60. Afrotropical Nylanderia species in various views: scintilla (worker, 46 – 48, CASENT 0179579, Ivory Coast); silvula (worker, 49 – 51, LACMENT 272717; queen 52 – 54, LACMENT 272721; male, 55 – 57, LACMENT 272719; all from Kenya); umbella (worker, 58 – 60, CASENT 0179583, Cameroon)

FIGURES 73 – 88. Scapes of Afrotropical Nylanderia species (workers only): boltoni (73, CASENT 0179580, Gabon); bourbonica (74, CASENT 0101309, Reunion); brevisetula (75, CASENT 0090304, Central African Republic); impolita (76, CASENT 0179589, Gabon); incallida (77, CASENT 0179576, Ivory Coast); jaegerskioeldi (78, CASENT 0179577, Kenya); lepida (79, CASENT 0179591, Gabon); luteafra (80, CASENT 0179584, Gabon); mendica (81, CASENT 0179590, Gabon); natalensis (82, CASENT 0396096, South Africa); scintilla (83, CASENT 0179579, Ivory Coast); silvula (84, LACMENT 272717, Kenya); umbella (85, CASENT 0179583, Cameroon); usambarica (86, CASENT 0235343, Tanzania); vaga (87, CASENT 0104253, U. S. A); vividula (88, CASENT 0103260, U. S. A.)