Leptoconops (Palaeoconops), BORKENT, 2001

BORKENT, ART, 2001, Leptoconops (Diptera: Ceratopogonidae), the Earliest Extant Lineage of Biting Midge, Discovered in 120 - 122 Million-Year-Old Lebanese Amber, American Museum Novitates 3328, pp. 1-12 : 3-7

Palaeoconops , new subgenus

DIAGNOSIS: Male and female. Only Leptoconops with a well­developed costa extending to the wing apex. Also, female. Only Leptoconops with an antenna with 13 flagellomeres.

TYPE SPECIES: Leptoconops amplificatus , n. sp.

TAXONOMIC DISCUSSION: Cladistic analysis of the two included species, L. amplificatus and L. antiquus , of the new subgenus Palaeoconops provided below, shows that these represent the earliest lineage within Leptoconops (fig. 4). All remaining Leptoconops

form a monophyletic group and the new fossil taxa must therefore be placed in a new subgenus. There is no synapomorphy grouping L. amplificatus and L. antiquus and it is therefore uncertain whether L. ( Palaeoconops ) is monophyletic.

DERIVATION OF SUBGENERIC EPITHET: The name Palaeoconops is from the Greek, palaeo (= ancient, old) and konops (= gnat), referring to the incredible age of these fossils.

Leptoconops (Palaeoconops) amplificatus Borkent , new species

Figures 1A–J , 2A

DIAGNOSIS: Male. The only Cretaceous Leptoconops with a well­developed costa beyond R 3, a well­developed R 4+5, and strong spines along the length of the first tarsomere of the hindleg. Female. The only species of Ceratopogonidae with 13 flagellomeres and an elongate, slender cercus.

DESCRIPTION: Male. Head: Most details not visible. Antenna (fig. 1A) with well­developed plume, basal foramen of pedicel not visible, 13 separate flagellomeres, antennal ratio = 0.69, flagellomere 10/11 = 0.77, flagellomere 13 more elongate than preceding flagellomeres (fig. 1B, G). Palpus with 4 segments, details not visible. Thorax: Most details not visible. Wing: Length = 0.64 mm. R 4+5 well­ developed to near wing apex. Costa well­developed to near wing apex, exact costal ratio uncertain. Without macrotrichia, fine microtrichia on all membrane. Legs: Femora, tibiae slender. Hindleg first tarsomere with numerous stout setae (fig. 1B). Setae on fore­ and midleg trochanter not visible. Midleg tibia with apical spur. Hindleg first tarsomere without thick basal spine or palisade setae. Claws simple. Genitalia (fig. 1C, D): Tergite 9 apparently tapering to single apex. Gonocoxite moderately elongate. Gonostylus thick basally, tapering to toothed apex; apical spine likely present but not clearly visible. Paired structures (parameres?) basally thick, tapering apically, directed posterolaterally. Aedeagus not visible.

Female. Head: Eyes bare, broadly separated dorsomedially. Vertex without single dorsomedial seta. Frons, vertex area possibly with sutures (fig. 1F). Antenna with 13 separate flagellomeres, antennal ratio = 0.75– 0.87 (n = 5), terminal flagellomere more elongate than preceding flagellomere (fig. 1H), penultimate flagellomere longer than preceding flagellomeres, first flagellomere sensilla not visible. Mouthparts moderately elongate (fig. 1F, G). Clypeus separated laterally by membrane from head capsule. Labrum with 4–6 short thick apical spines. Mandible with fine teeth. Lacinia with at least 15 large, retrorse teeth. Palpus with 4 segments, third segment somewhat ovoid, capitate sensilla not visible (fig. 1G), palpus segment 3/4 + 5 = 1.27–2.00 (n = 5). Hypopharynx not visible. Thorax: Most details not visible. Anterior scutal apodemes not visible. Scutum with a few scattered elongate setae. Wing (fig. 1E): Length = 0.47–0.65 mm (n = 6). R 4+5 well­developed to near wing apex. Costa well­developed to near wing apex, apex of R 3 /wing length = 0.38– 0.40 (n = 3). Without macrotrichia, fine microtrichia present on all membrane. Alula without macrotrichia. Single radial cell present in at least some specimens, radial veins compacted anteriorly. Base of M poorly defined, bifurcation not visible, both M 1 and M 2 present. Legs: Femora, tibiae slender. Legs with thick spines on first tarsomere of each leg, a few on fore and midleg, many on hindleg (fig. 1I). Pair of thick setae on fore­ and midleg trochanter not visible. Midleg tibia with apical spur. Hind first tarsomere without thick basal spine or palisade setae. Foreleg, midleg, hindleg claws of equal size, length, more or less evenly curved, without well­developed basal tooth (fig. 1J). Genitalia (fig. 2A): Spermathecae not visible. Details of sternite 8, 9, segment 10 not visible. Cercus laterally compressed, elongate, slender.

BIONOMICS: Based on the elongate cerci (likely used to oviposit in sand) and the general habitat of extant members of the genus, L. amplificatus probably bred in sandy, saline habitats (Borkent, 1995). The presence of finely serrate mandibles and laciniae with retrorse teeth strongly suggests that females of this species fed on vertebrate blood (Borkent, 1995, 1996). One female paratype of L. amplificatus in piece 101 (specimen No. 3, fig. 3) had a bloated abdomen and, considering the evidence from the mouthparts, this is likely due to the presence of either a vertebrate blood meal or nectar.

The holotype of L. amplificatus was associated with eight paratypes of that species, in addition to a female Ceratopogonidae of uncertain identity, one Mycetophilidae , three Brachycera, one Chironomidae and one Culicomorpha. The allotype and one paratype of L. amplificatus were in a single piece of amber with the holotype of L. antiquus and the holotype of a possible Lonchopteridae ( Lonchopterites prisca Grimaldi and Cumming ). The paratype in piece 131 was associated with a female Rhagionidae identified by Grimaldi and Cumming (1999) as ‘‘Genus C’’. The implications of these associations are interpreted below.

TAXONOMIC DISCUSSION: The male was associated with the female on the basis of the presence of numerous thick spines on the first tarsomere of the hindleg (not present in females of L. antiquus ).

The holotype of L. amplificatus was in moderately good condition, but was missing the apex of the left antenna and the apices of all legs other than the right hindleg. The allotype was also in moderately good condition, but was embedded so deeply in the amber as to make some details difficult to discern. The remaining paratypes were generally in moderately good to excellent condition but some of those in piece 101 (fig. 3) were buried so deeply in the amber— which cannot be cut further because of other inclusions—that visibility was rather limited for these.

The holotype of L. amplificatus was the middle specimen in a group of three closely approximated females (fig. 3). The paratype of L. amplificatus in piece 79 was that female most close to the holotype of Lonchopterites prisca (amber piece figured in Grimaldi and Cumming, 1999: 83, showing the position of the specimens).

One female paratype in piece no. 101 (specimen no. 4) appeared to have sutures on the frons/vertex (fig. 1F), but these may have been artifacts of preservation. If truly present, these would be unique within the genus.

TYPES: Holotype, female adult in amber in plastic box, labeled ‘‘ HOLOTYPE Leptoconops amplificatus Borkent’’, ‘‘ PARATYPES Leptoconops amplificatus Borkent : 8 females’’, ‘‘Amber: N. Lebanon, Antoni Estephan Coll. Bchare Mtn., 2300 m’’, ‘‘AMBER: Lebanon Lower Cretaceous (Neocomian) No. 101, Amer. Mus. Nat. Hist., Inclusion(s): female Leptoconops ’’ (AMNH); allotype, male adult, labeled ‘‘ ALLOTYPE Leptoconops amplificatus Borkent’’, ‘‘ PARATYPE Leptoconops amplificatus Borkent’’, ‘‘ HOLOTYPE Leptoconops antiquus Borkent’’, ‘‘Amber: N. Lebanon, Antoni Estephan Coll. Bchare Mtn., 2300 m’’, ‘‘AMBER: Lebanon Lower Cretaceous (Neocomian) No. 79, Amer. Mus. Nat. Hist., Inclusion(s): 3 Ceratopogonidae , 1 Empidoid’’ (AMNH); paratypes, 10 females: 8 in same piece with holotype; 1 in same piece as allotype; 1 from Bchare Mtn., Lebanon, piece No. 131 (AMNH).

DERIVATION OF SPECIFIC EPITHET: The name amplificatus (enlarged, extended) refers to the presence of 13 flagellomeres in the female antenna.

Leptoconops (Palaeoconops) antiquus Borkent , new species

Figures 2B–G

DIAGNOSIS: Male. Unknown. Female. The only species of Ceratopogonidae with 13 flagellomeres and an elongate and basally broadened (anteroventrally) cercus.

DESCRIPTION: Female. Head: Most details not visible. Antenna with 13 separate flagellomeres, antennal ratio = 0.78–0.89 (n = 2), terminal flagellomere more elongate than preceding flagellomeres (fig. 2C), first flagellomere sensilla not visible. Mouthparts moderately elongate. Clypeus not clearly visible. Labrum, mandible not visible. Lacinia with at least seven large, retrorse teeth. Palpus with 4 segments, third segment large, somewhat ovoid, capitate sensilla not visible (fig. 2D, E), palpus segment 3/4 + 5 = 1.80 (n = 1). Thorax: Most details not visible. Wing (fig. 2B): Length = 0.59 mm (n = 2). R 4+5 well­developed to near wing apex. Costa well­developed to near wing apex, apex of R 3 /wing length = 0.38 (n = 1). Without macrotrichia, fine microtrichia present on all membrane. Alula without macrotrichia. Without radial cell, radial veins compacted anteriorly. Base of M poorly defined, point of bifurcation not visible, both M 1 and M 2 present. Legs: Femora, tibiae slender. Legs mostly lacking armature but with four to five thick spines on fifth tarsomere of hindleg. Pair of thick setae on fore­ and midleg trochanter not visible. Midleg tibia with apical spur. Hind first tarsomere without thick basal spine or palisade setae. Foreleg, midleg, hindleg claws equal, more or less evenly curved, inner tooth not visible (fig. 2F). Genitalia (fig. 2G): Spermathecae not visible. Details of sternite 8, sternite 9, segment 10 not visible. Cercus laterally compressed, elongate, broad basally (anteroventrally).

BIONOMICS: Based on the elongate cerci and the general habitat of extant members of the genus, L. antiquus likely bred in sandy, saline habitats (Borkent, 1995).

The holotype of L. antiquus had a number of associations in the same piece of amber: a male and female of L. amplificatus and the holotype of a possible Lonchopteridae ( Lonchopterites prisca ). The presence of laciniae with retrorse teeth suggests that females of this species fed on vertebrate blood (Borkent, 1995, 1996). The significance of these associations is interpreted below in the discussion. The amber holding the paratype also included a small, poorly preserved arachnid (spider or possibly a mite?).

TAXONOMIC DISCUSSION: The allotype of L. antiquus is that specimen of Leptoconops in piece no. 79 most distant from the holotype of Lonchopterites prisca ; the amber piece was drawn in Grimaldi and Cumming (1999: 83), illustrating the position of the specimens.

The holotype of L. antiquus is quite decomposed and part of the head and thorax are obscured by contaminants; the left wing is missing. Much of the body of the paratype is collapsed and portions appeared distorted.

The paratype of L. antiquus differs from the holotype in some details: flagellomere 12 is more elongate, third palpal segment is more spherical (fig. 2 D–E), and the cerci may be more elongate. These differences may indicate the presence of two species, but may also be due to artifacts of preservation, especially considering that both specimens were in only moderate condition.

TYPES: Holotype, female adult in amber in plastic box, labeled ‘‘ HOLOTYPE Leptoconops antiquus Borkent’’, ‘‘ ALLOTYPE Leptoconops amplificatus Borkent’’, ‘‘ PARATYPE Leptoconops amplificatus Borkent’’, ‘‘Amber: N. Lebanon, Antoni Estephan Coll. Bchare Mtn., 2300 m’’, ‘‘AMBER: Lebanon Lower Cretaceous (Neocomian) No. 79, Amer. Mus. Nat. Hist., Inclusion(s): 3 Ceratopogonidae , 1 Empidoid’’ (AMNH); paratype, 1 female, labeled ‘‘ PARATYPE Leptoconops antiquus Borkent’’, ‘‘Amber: N. Lebanon, Antoni Estephan Coll. Bchare Mtn., 2300 m’’, ‘‘AMBER: Lebanon Lower Cretaceous (Neocomian) No. 125, Amer. Mus. Nat. Hist., Inclusion(s): female Leptoconops ?’’ (AMNH).

DERIVATION OF SPECIFIC EPITHET: The name antiquus (ancient) refers to the old age of this Lebanese amber fossil species.

Figures

Fig. 1. Structures of Leptoconops amplificatus. A–D. Male (no. 79). E–J. Female. A. Antenna. B. Hindleg tarsomeres. C. Genitalia, oblique, dorsal view. D. Genitalia, oblique, lateral view. E. Wing Antenna (no. 101, holotype). F. Head capsule, anterior view (no. 101, paratype # 4). G. Apex of mouthparts (no. 101, holotype). H. Antenna (no. 101, holotype). I. First and second tarsomeres of hindleg (no. 101, holotype). J. Fifth tarsomere of midleg (no. 101, holotype).

Fig. 2. A. Structures of female Leptoconops amplificatus. B–G. Structures of female Leptoconops antiquus. A. Cercus, lateral view (no. 101, holotype). B. Wing (no. 125, paratype). C. Antenna (no. 125, holotype). D. Apex of mouthparts (no. 125, holotype). E. Palpus (no. 125, paratype). F. Fifth tarsomere of foreleg (no. 125, paratype). G. Cerci, lateral view (no. 125, holotype).