Homalictus ostridorsum, Dorey & Schwarz & Stevens, 2019

Dorey, James B., Schwarz, Michael P. & Stevens, Mark I., 2019, Review of the bee genus Homalictus Cockerell (Hymenoptera: Halictidae) from Fiji with description of nine new species, Zootaxa 4674 (1), pp. 1-46 : 32-35

Homalictus ostridorsum sp. nov.

( Figs 21–22 )

Material examined. Holotype ♂: 17FJ141 (SAMA 32-036194), 17/4/17, 10:45 AM, 1,328 m asl, -17.614762, 178.018284, JB Biddle, JB Dorey, CS Matthews & RK Schober, peak of Mt. Tomanivi , cleared patch of grass, no flowers, general sweep, sunny, light breeze.

Allotype ♀: 17FJ101 (SAMA 32-036195), Viti Levu, Fiji, -17.615347, 178.017228, Q, JB Dorey, JB Biddle, RK Schober, 18.04.2017, 1,289 m asl, Tomanivi Clade, HG 17CM0028, Mt. Tomanivi ; open area along ridge between peaks, Sun out, low wind, clear weather grassy open area.

Paratypes 2 ♂: 17FJ110 (SAMA 32-036196) and 17FJ111 (SAMA 32-036197), 18/4/18, 12:31 PM, 1,289 m asl, -17.615347, 178.017228, JB Biddle, JB Dorey & RK Schober, open area along ridge between peaks of Mt. To- manivi , sun out and low wind; and 2 ♀: 17FJ119 (SAMA 32-036198), 18/4/17, 1:45 PM, 1,303 m asl, -17.616583, 178.016600, JB Biddle, JB Dorey & RK Schober, caught on ridge between peaks but closer to lookout. Clear, sunny and breezy, and 17FJ143 (SAMA 32-036199), 17/4/17, 10:45 AM, 1,328 m asl, -17.614762, 178.018284, JB Biddle, JB Dorey, CS Matthews & RK Schober, cleared patch of grass with no flowers at top of Mt. Tomanivi , sunny and a light breeze. General sweep of grasses and flowers .

Other material examined. 1 ♂: 17FJ152, 18/4/17, 2:30 PM, 1,222 m asl, -17.614691, 178.017909, JB Dorey & CS Matthews, open vegetated area flat just before an incline going towards peak, few dead trees sticking up along ridge, swept off grass and plants, stiff breeze, no canopy. 1 ♀: 17FJ131, 17/4/17, 10:45 AM, 1,328 m asl, - 17.614762, 178.018284, JB Biddle, JB Dorey, CS Matthews & RK Schober, peak of Mt. Tomanivi , cleared patch of grass, no flowers, general sweep, sunny, light breeze .

Diagnosis. Males: In combination: Supraclypeal area mostly finely colliculate ( Fig. 1 f–g) and scutum and scutellum mostly golden, purple, blue and/or pink.

Females: In combination: Supraclypeal area mostly finely colliculate ( Fig. 1 f–g), scutum and scutellum mostly purple, with some orange and green ( Fig. 21f ) and pygidial plate has close fine punctures ( Figs 2 , 21i ).

Description. Males: Measurements: UID 0.67–0.77 mm. LID 0.53–0.59 mm. AOD 0.19–0.28 mm. IAD 0.13– 0.15 mm. OAD 0.33–0.37 mm. IOD 0.17–0.0.18 mm. OOD 0.21–0.22 mm. GW 0.17–0.27 mm. EW 0.25–0.35 mm. BL 4.13–4.66 mm. ML 0.09–0.12 mm. SL 0.27–0.33 mm. FL 3.7–4.67 mm.

Colouration: Clypeus, supraclypeal area, paraocular area and propdeum dorsally golden green and metallic. Scutum blue posteriorly, pink and orange medially, golden green and metallic anteriorly and laterally. Scutellum orange, golden and some pink and blue. Metasoma black.

Sculpturing: Paraocular area some horizontal striae along central margin of compound eyes and longitudinal striae, colliculate along margin of compound eyes. Frons many diagonal striae and some transverse striae under ocelli. Supraclypeal area mostly finely colliculate. Clypeus finely colliculate. Vertex punctures small and close. Scutum finely colliculate. Scutellum punctuation open and sparse. Propodeum dorsally coarsely strigate-rugose with strong striae and a strong or weak medial anterior groove; laterally finely colliculate, lineolate and posteroventral and anterior striae curve towards each other and can meet; posteriorly finely colliculate and diagonal striae ventrally and proximally.

Morphology: Scape extends to posterior margin of medial ocellus. Interantennal distance greater than diameter of socket. Labrum simple. Clypeus not depressed medially. Area posterior of vertex with strong striae, striae close, lineolate and finely colliculate. Posterior margin of Scutum shape mostly straight. Gonostylus moderate, dorsoapical crest of gonocoxite moderate with a small proximal and posterior projection.

Females: Measurements: UID 0.72–0.89 mm. LID 0.7–0.86 mm. AOD 0.25–0.5 mm. IAD 0.12–0.13 mm. OAD 0.41–0.48 mm. IOD 0.17–0.19 mm. OOD 0.21–0.25 mm. GW 0.25–0.36 mm. EW 0.3–0.34 mm. BL 5.88– 6.03 mm. ML 0.14–0.16 mm. SL 0.3–0.35 mm. FL 3.94–4.42 mm.

Colouration: Clypeus anteriorly black; middle iridescent; posteriorly golden green and metallic. Supraclypeal area golden green metallic, orange medially. Frons, paraocular area and Propodeum dorsally golden green and metallic. Scutum mostly purple. Scutellum mostly purple, some orange and green. Metasoma black.

Sculpturing: Paraocular area some horizontal striae along central margin of compound eyes and colliculate, longitudinal striae posteriorly and proximally above antennal socket. Frons mostly longitudinal striae and transverse striae under ocelli. Supraclypeal area mostly finely colliculate. Clypeus finely colliculate. Vertex punctures small and close or fine and sparse. Scutum anteriorly moderately colliculate and lineolate; medially moderately fine colliculate; posteriorly finely colliculate. Scutellum punctation close. Propodeum; dorsally strong striae, weak medial anterior groove and coarsely strigate-rugose; laterally finely colliculate and posteroventral and anterior striae curve towards each other and can meet; posteriorly finely colliculate, striea medially and ventrally curve dorsally and then ventrally towards the sides and medial striae diagonal. Pygidial plate with close and fine punctures.

Morphology: Scape extends to above vertex. Interantennal distance less than or about equal to diameter of sock- et. Labrum has two medial projections parallel from one another. Clypeus not depressed medially. Area posterior of vertex with strong striae, lineolate and finely colliculate. Posterior margin of scutum shape mostly straight.

Comments. Given the very limited geographical and elevational distribution of H. ostridorsum , similar to that of H. achrostus , it is also likely to be threatened by future climate warming.

Distribution. Homalictus ostridorsum has only been sampled from Mt. Tomanivi (the highest mountain in Fiji and previously known as Mt. Victoria) on the main island of Viti Levu ( Fig. 22 ). Samples were collected between 1,200 m asl and 1,328 m asl, the latter is the highest elevation of Mt. Tomanivi.

Etymology. Both the males and females of this species have a purple scutum. The name is derived from the Latin ostrum meaning ‘purple’ and dorsus meaning ‘back’.

Figures

FIGURE 1. Propodeum dorsally showing (a) coarsely, (b) moderately and (c) finely strigate-rugose sculpturing. Fovea along anterior inner margin of eye (d) present and (h) absent. Supraclypeal area showing (e) mostly moderately, (f) mostly finely and (g) entirely finely sculpturing.

FIGURE 2. Grades of (a) pit density and (b) pit size. Reproduced from Houston (1975) with permission from CSIRO Publishing.

FIGURE 21. Homalictus ostridorsum sp. nov. male (a) dorsal habitus, (b) lateral habitus, (c) dorso posterior, (d) anteriorly frontal face and (e) ventral genitalia. Female (f) dorsal habitus, (g) lateral habitus, (h) dorso posterior, (i) anteriorly frontal face and (j) pygidial plate.

FIGURE 22. Collection map of Homalictus ostridorsum sp. nov. from specimens with identity confirmed by mtDNA COI gene. Sample size is 43.