Lindenius paleomystax, BENNETT & ENGEL, 2006

BENNETT, DANIEL J & ENGEL, MICHAEL S, 2006, A New Moustache Wasp in Dominican Amber, with an Account of Apoid Wasp Evolution Emphasizing Crabroninae (Hymenoptera: Crabronidae), American Museum Novitates 3529 (1), pp. 1-12 : 2-6

Lindenius paleomystax , new species

Figures 1–5

DIAGNOSIS: The new species is immediately recognizable as a member of the Crabroninae owing to large cuboidal head, single submarginal cell, elongate scape, and nonemarginate eyes. It is further distinguished as a member of the subtribe Crabronina by ventrally convergent eyes, toruli positioned very low and close together on face, and ventral margin of mandibles entire ( Bohart and Menke, 1976). It is placed in Lindenius by mandible with apex simple, ventral margin entire (figs. 1, 2, 4), ocellar triangle broader than high, scapal basin ecarinate, and hind wing longer than second cubital cell (submedian cell) ( Bohart and Menke, 1976). With

possible exception of the latter trait (which is not visible in the type material), the new species can be diagnosed by these characters in combination with the lack of an inner basal mandibular tooth (figs. 2, 4) and a clypeal margin as figured (figs. 2, 4) and described below.

DESCRIPTION: Female: Body length excluding antenna approximately 4.2 mm; head width 1.5 mm, height 0.8 mm; forewing length 3.4 mm. Color dark brown to black with brown maculations on pronotal lobe, antenna, tegula, and mandible, mandibular apex black; wing veins dark brown to black, membrane hyaline. Integument apparently imbricate. Antennal scape elongate, length approximately equal to three-fourths mandibular length, ecarinate; medial flagellomeres about as long as wide, becoming more compact apically and slightly longer basally. Clypeus short and narrow; apical margin denticulate, with three teeth lateral of medial concavity, submedial tooth broad, middle tooth longer and pointed, lateral tooth shorter and pointed (figs. 2, 4). Toruli narrowly separated, positioned low on face, meeting epistomal sulcus, scapal basin shallow and ecarinate, without medial tubercle. Gena broad behind compound eye, orbital fovea weakly present, not margined by carina (observable only in paratype), ocellar triangle broader than high, ocelli apparently all of similar size. Occipital carina present dorsally and laterally, not observable ventrally. Compound eyes large, bare, strongly convergent below, reaching clypeal margin laterally; separated from toruli by slightly less than torular diameter. Mandible simple and apically acuminate, ventral margin entire. Three segments of labial palpus visible (in paratype); three relatively long maxillary palpal segments visible (in paratype), apical segment nearly twice as long as subapical segment; pronotal collar rounded, medial notch weak (especially in paratype), strongly notched laterally. Mesoscutum simple, admedian lines, notauli, and parapsidial lines not apparent. Mesoscutellum and metanotum simple, prescutellar sulcus foveate. Postspiracular carina and epicnemial carina present, continuous; acetabular carina apparently absent, verticaulus, sternaulus, and mesopleuralus absent; hypersternaulus present, episternal groove foveate, scrobe distinct. Anteromedial section of propodeal spiralcle meeting upper arm of sideways Y-shaped carina, lower arm of carina bounds spiracle ventrally and intersects with dorsal end of weak lateral carina of propodeum; propodeal enclosure defined by transverse carina (observable in dorsal view of holotype, challenging to discern in posterior view but present), posterior longitudinal depression apparent below enclosure. Forewing basal vein distad cu-a by distance approximately equal to length of cu-a; Rs separating from Sc+R at point anterior to pterostigmal base approximately equal to length of posterior border of pterostigma within submarginal cell; marginal cell about as long as submarginal cell; apical margin of truncate marginal cell approximately equal to apical margin of submarginal cell; 1m-cu (recurrent vein) meeting posterior margin of submarginal cell near cell midpoint (fig. 5). Protrochanter widest apically, about 2.6 times as long as wide; protochantellus narrow and ringlike; profemur widest medially, about 3.5 times longer than wide; protibia widest slightly distad middle, about 4.4 times longer than wide, lightly spinose, with spur as long or nearly as long as antenna cleaner. Mesofemur expanded medially, about 2.2 times longer than wide; mesotibia somewhat expanded distad middle, about 3.7 times longer than wide, rather strongly spinose with anterior spur about twice length of posterior spur. Metafemur widest medially, about 2.7 times longer than wide; metatibia widest subapically, about 3.4 times longer than wide, spinose, with anterior spur roughly two-thirds length of posterior spur. Basitarsus about as long as combined lengths of tarsomeres II–V; tarsomeres progressively shorter except for distitarsi, which are longer than preceding tarsomeres. Pretarsal claws simple, arolia distinct. Metasoma sessile, relatively compact, roughly two-thirds as wide as mesosoma; second through fourth metasomal sterna subequal in length except third apparently slightly longer; pygidial plate flat, triangular, longer than broad, evenly narrowed, with apex truncate and punctuate throughout, somewhat more strongly so apically.

HOLOTYPE: Female (AMNH DR-14-1091), Dominican Republic: Early Miocene (Burdigalian) amber, specific mine unknown. Deposited in the Amber Fossil Collection , Division of Invertebrate Zoology, American Museum of Natural History.

PARATYPE: Female (AMNH DR-14-236), Dominican Republic: Early Miocene (Burdigalian) amber, northern mines. Deposited in the Amber Fossil Collection , Division of Invertebrate Zoology, American Museum of Natural History .

ETYMOLOGY: The specific epithet is a combination of the Greek words for ‘‘ancient’’ (palaios) and ‘‘moustache’’ (mystax), a reference to the common name for the subtribe Crabronina .

COMMENTS: One major difference between the fossil and its modern relatives is the lack of an inner basal mandibular tooth in the former. Although a cladistic analysis of the Crabronina is needed to be certain of its polarity, the tooth is likely a feature derived within Lindenius . It occurs in other moustache wasps (e.g., Huavea, Moniacera , some Crossocerus , and most Ectemnius ) but not in any obviously closely related group. Based on this character alone, the species could plausibly be interpreted to represent an extinct lineage basal within Lindenius , outside of modern species groups as outlined by de Beaumont (1956) (see also summary in Bohart and Menke, 1976). However, such an interpretation is not congruent with the presence of a hypersternaulus, a character that suggests placement in the mesopleuralis species group of Lindenius . The correct placement of the fossil within the genus must await a broader analysis of additional characters.

Figures

Figs. 1–3. Photomicrographs of holotype female of Lindenius paleomystax, new species (AMNH DR-14- 1091). 1. Oblique lateral habitus. 2. Facial aspect. 3. Dorsal aspect.

Figs. 4–5. Line drawings of Lindenius paleomystax, new species, as preserved. 4. Face depicting clypeal margin. 5. Apical two-thirds of forewing.