Pagastia menieri, Published, 2007

Published, First, 2007, Chironomid midges from early Eocene amber of France (Diptera: Chironomidae), Zootaxa 1404, pp. 1-66: 55-57

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Pagastia menieri

n. sp.

Pagastia menieri   n. sp.

( Figs. 54, 55)

Etymology: We name this species after Prof. Jean­Jacques Menier for his help in the collection and study of the Oise amber insects.

Diagnosis: Five palpomeres, apex of palpomere 3 without projection, head without orbital setae, eyes bare, tarsomeres 4 cylindrical not cordiform, MCu distal to FCu but proximal to RM, absence of pseudospurs on tarsomeres of mid and hind legs, antennal ratio low, few dorsal antepronotals.

Description: Head deformed, 0.34 mm long; ocelli absent; antenna 0.6 mm long, much longer than head, distinctly hairy, with 14 flagellomeres covered with long setae (shortest 0.008 mm long, longest 0.18 mm long), 13 th flagellomere 0.3 mm long, 14 th with distinctly apical nipple and long subapical seta, antennal ratio 1.14; pedicel broad and short, rounded, with 1 or more setae; eye bare but deformed, with apically expanded dorsomedial extension, with 4 or fewer rows of ommatidia at minimum width; mouthparts lacking functional mandibles; 5 palpomeres with numerous setae and all cylindrical; 3 postoculars, frontal, inner vertical and outer vertical setae not visible. Thorax 0.6 mm long, 0.3 mm wide; postnotum bare, without longitudinal median groove; surface of scutellum with few long setae; scutal tubercle not visible; few prealar setae and no supraalar setae; numerous anterior acrostichals present and biserial; numerous dorsocentrals uniserial; preepisternal setae absent. Wing macropterous, 1 mm long, 0.3 mm wide, hyaline, with macrotrichia; anal vein An 2 absent; radius with 3 branches R 1, R 2+3, and R 4+5; R 2+3 well separated from R 1 and nearly to R 4+5, R 2+3 not divided into R 2 and R 3; costa ending just beyond insertion of last branch of radius, produced by 0.03 mm, less than length of cross­vein RM; only M 1+2 and M 3+4 present; cross­vein MCu present, distal to FCu (0.025 mm long) but proximal to RM, cross­vein RM 0.4 mm long. Halter 0.08 mm long. Fore femur 0.38 mm long, tibia 0.43 mm long, tarsus 0.8 mm long; mid femur 0.39 mm long, tibia 0.44 mm long, tarsus 0.68 mm long, hind femur 0.38 mm long, tibia 0.45 mm long, tarsus 0.9 mm long; 1 long spur on mid and hind tibiae; tarsomere 4 of all legs cylindrical, not cordiform; hind tibial comb of 1 row, pulvilli absent, no pseudospur on tarsomeres. Abdomen 0.82 mm long, 0.16 mm wide; gonostylus not visible; gonocoxite 0.06 mm long, 0.05 mm wide, numerous long setae on outer surface of gonocoxites; anal point present.

Discussion: Pagastia menieri   n. sp. is in the Diamesinae Kieffer, 1923   , according to the key to subfamilies of Oliver & Dillon (1989), based on the following characters: macropterous, MCu present, R 2+3 present but not forked, and MCu distal to FCu but proximal to RM. Among the non­Holarctic subfamilies, affinities with the Aphroteniinae   are excluded because Pagastia menieri   n. sp. has retained MCu and R 2+3, but it has a narrow space between R 4+5 and the costa. Usambaromyiinae   have no MCu. The Chilenomyiinae   have MCu in a basal situation, but no R 2+3. Brundin (1966) proposed a phylogeny of the Diamesinae   and divided them into Protanypodini Brundin, 1956   , Diamesini Kieffer, 1922   , Harrisonini Brundin, 1966, Boreoheptagyiini Brundin, 1966   , Lobodiamesini Brundin, 1966   , and Heptagyiini Brundin, 1966. (Further information on the names is provided by Spies (2005)). Kalugina (1976) added the Cretaceous tribe Cretodiamesini   , based on the genus

FIGURE 55. Pagastia menieri   n. sp., holotype PA 1077, drawing of male genitalia (scale bar = 0.1 mm).

Cretodiamesa Kalugina, 1976   . This fossil taxon differs from Pagastia menieri   by the male antenna with six flagellomeres, five of them being very short and the last one very long ( Kalugina 1976: 78, fig. 2). The Protanypodini   are excluded because Pagastia menieri   has no setae on the anepisternum, epimeron II, or preepis­ ternum, unlike Protanypus Kieffer, 1906   . The Boreoheptagyiini   ( Boreoheptagyia Brundin, 1966   ) have male antennae with reduced plumes and an antennal ratio less than 0.25, unlike in Pagastia menieri   . The Harrisonini ( Harrisonina Freeman, 1956   ) have only four palpomeres (instead of five), male antennae with reduced plumes, and pubescent eyes ( Freeman 1956). The Lobodiamesini   ( Lobodiamesa Pagast, 1947   ) have hairy eyes, setae along the whole margin of the antepronotal lobes, and tarsomere 4 cordiform, unlike in Pagastia menieri ( Brundin 1966)   . Brundin (1966) divided the Heptagyiini into five recent genera that all differ from Pagastia menieri   in the relative positions of RM, MCu, and FCu. The only remaining tribe is the Diamesini   , in which Pagastia menieri   also falls in the key to Holarctic genera of Oliver (1989). Within this tribe, Pagastia menieri   would fall near the recent genus Pagastia Oliver, 1959   ( Oliver 1959, 1989). Endo (2004) indicated that at least some recent species have no pseudospurs on the fore leg, but Pagastia menieri   differs again from the recent genus Pagastia   in the absence of pseudospurs on the tarsomeres of the mid and hind legs, an antennal ratio less than in all species, and the number of dorsal antepronotals, which is very important in the recent species, unlike in Pagastia menieri   .

Meunier (1899) described and gave a rudimentary figure of the Baltic amber genus and species Jentzschiella jentzschi Evenhuis, 1994   . Ashe (1983) considered that this enigmatic taxon could be in the Diamesinae   but that it needed redescription.

Material: Holotype PA 1077, (male).