Stelis (Malanthidium) flavofuscinular Nalinrachatakan & Warrit, 2021

Nalinrachatakan, Pakorn, Traiyasut, Prapun, Khongnak, Anupong, Muangkam, Manop, Ascher, John S. & Warrit, Natapot, 2021, The resin bee subgenus Ranthidiellum in Thailand (Megachilidae, Anthidiini): nesting biology, cleptoparasitism by Stelis, and new species, ZooKeys 1031, pp. 161-182 : 161

Stelis (Malanthidium) flavofuscinular Nalinrachatakan & Warrit sp. nov. Figs 6 , 7

Type locality.

Thailand: Ubon Ratchathani, PCNYNP, Kaeng Ka Lao [14°26'10.98"N, 105°16'37.05"E, alt. 322 m]

Material examined

2 (2 ♂). Holotype: 1♂, emerged from a reared nest on the 25th Dec. 2019, A. Khongnak & M. Muangkam coll. (CUNHM: BSRU-AB-0157). Paratype: 1♂, same as in holotype, emerged on 23rd Dec. 2019 (CUNHM: BSRU-AB-0156).

Diagnosis.

With only males known, Stelis flavofuscinular is distinct from its only known congener, S. malaccensis from Malaysia, as follows: head overall black, with yellow paraocular mark reaching close to the top of eyes, and narrow mark restricted close to apical area of clypeus; antennal scape black; Mesosoma overall black except yellow on postero-lateral hook of axilla; T1-T5 with large yellow strike band, with little median disruption that is pronounced more on rear metasomal segments; T6 with lateral yellow dots; S2-S4 with distinct median patch of long white hairs, while lacking black midapical comb. S4 and genitalia as in Fig. 7G .

Description.

Male holotype: Body length 8.2 mm, head width 2.4 mm, intertegular distance 2.1 mm, wingspan 16.1 mm. Paratype: Body length 8.1 mm, head width 2.5 mm, intertegular distance 2.0 mm, wingspan 15.9 mm.

Head. Largely black, overall covered with sparse pale white hairs. Mandible black with red-brown infused, tridentate, with apically large acute tooth. Labrum black with rounded margin. Clypeus black with narrow yellow stigma (obscured in BSRU-AB-0156) on surface close to apex, punctures very dense, separated with less than half of its diameter, margin truncate, with small inconspicuous median tubercle. Subantennal suture strait. Frons punctures coarser than on clypeus, with two yellow stigmas (Fig. 6B ), typically very obscured but can be recognized in BSRU-AB-0157, present above area between antennal socket. Paraocular area with yellow mark extending along orbit close to top of ommatidia. Interocellar distance shorter than ocellooccipital distance. Vertex and preoccipital area with coarse and dense punctures, with distinct microsculptures. Surfaces nearby lateral ocelli shiny glabrous, with fewer punctures, whereas fine and dense around middle ocelli. Scape and pedicels brown-black, frontal surface covered with dense pale white hairs. Antennal flagellum dark brown, F1 color lighter in apical half, F2 almost broader than long.

Mesosoma. Overall black, covered with sparse pale white hairs. Pronotal lobe rounded. Omaulus carinated but does not reach venter of thorax. Mesepisternum swollen laterally, with fine dense punctures on anterior surface, very coarse and dense on lateral surface.

Scutum with coarse, dense punctures, separated by about half of its diameter, becoming fine and dense posteriorly. Scutellum rounded, extended posteriorly to overhang propodeum, punctation rather sparse in comparison with scutum. Scutoscutellar suture open, divided into two shiny bottom foveae. Axilla black (Fig. 6D ), postero-lateral hook yellow, punctures fine and dense. Scutum, scutellum, and axilla come with distinct microsculptures. Tegula large, dark brown to black, with very fine, dense punctures. Propodeum black, median area shiny glabrous, with distinct fovea behind spiracle.

Wings. Dark brown to black especially on anterior half of forewing, and marginal cell. Stigma black. Second recurrent vein enters distal to 2nd submarginal crossvein, separating medial vein in 4:1 ratio.

Legs. Overall black-brown, with restricted yellow maculation present on anterior surface of tibia and apical femur of foreleg, dorsal surface of apical femur and basal tibia of midleg. Fore and mid tibia apically with two outer apical spines. Hind tibia apically with outer rounded projection. Tibial spur pale, bifid on foreleg. Hairs pale white, brown on tarsi. Hind basitarsus black, inner surfaces with brown dense hair fringe. Claw red-brown, apically black on hind tarsi. Arolia present, light brown.

Metasoma. Overall black with yellow maculation. Tergites covered with sparse, short, brownish hair, punctation coarse, separated by its diameter, uniformly distributed but somewhat confused on T6. T1-T5 with large yellow strike bands, with little median disruption that is pronounced more in rear metasomal segments. T6 large with lateral dots, apical margin rounded, carinated, forming ventral border. T7 small, marginal area depressed, median area of apical margin broadly crenulate with distinct median erected tooth that making lateral shallow emargination, ventral surface smooth with lateral angle making T7 weakly tridentate. Sternite black, with scattered brownish hairs. S1 median carina strong, premarginal carina strong, extended ventrally but not clearly overhanging margin. S2-S4 (Fig. 6G ) laterally translucent, with distinct median white pubescent erected from premarginal band. S2 and S3 with yellow premarginal bands, but very narrow and medially restricted in the latter. S5 widely emarginated, with very sparse white pubescent. S6 margin rounded. S7 very narrow, ventral surface smooth, lateral margin with extended rounded lobe with dispersed erected hairs. S8 (Fig. 7F ) very clear apically, extending to two rounded apical lobes separated with median U-shape notch, resembling inverted heart shape. Genitalia as in Fig. 7G .

Etymology.

The word flavo means “yellow”, while fuscinular means “hook”. Thus, the specific epithet, Stelis flavofuscinular , principally refers to the yellow postero-lateral axilla hook of male bees that contrasts with its overall black mesosoma.

Bee host.

Anthidiellum phuchongensis sp. nov. (see above). It is possible that S. flavofuscinular sp. nov. may also be a cleptoparasite of other Megachile species that are also frequently encountered in the PCNYNP area. Kasparek (2015) suggested that the hosts of Stelis species are mainly members of Megachilinae , and some Stelis species have a wide range of hosts.

Floral association.

Unknown.

Remarks.

Though the color pattern observed on the mesosoma and metasoma seems invariant, there are some variations in the yellow maculation especially on the face, noticeable in two specimens possibly from the same cohort, and so it is likely to have a greater level of variation in the population. Stelis (M.) malaccensis (Friese, 1914), redescribed by Pasteels (1969), differs mainly in coloration. It exhibits very dense punctures over all the thorax, a more subtriangular scutellum, yellow markings on the base of the mandible, scape, supraclypeal area, paraocular area, preoccipital area, vertex, mesopleuron, anterolateral margin of the scutum, and margin of the scutellum and axilla.

Figures

Figure 6. Male Stelis flavofuscinular sp. nov. [A, B holotype (BSRU-AB- 0157) C-G paratype (BSRU-AB- 0156)] showing the A dorsal habitus B, C face D axilla, with postero-lateral hook highlighted in green E lateral habitus F metasomal apex G ventral habitus. Scale bars: 2 mm (A, E, G), 1 mm (B, C, F), or 0.5 mm (D).

Figure 7. Genitalia and terminalia of male Stelis flavofuscinular sp. nov. (BSRU-AB- 0157) A S 4 B S 5 C T 7 D S 6 E S 7 F S 8 G genitalia coupled with S 8 in ventral habitus. Scale bars: 0.5 mm.