Microphorites utrillensis Peñalver

Arillo, Antonio, Peñalver, Enrique & Delclòs, Xavier, 2008, Microphorites (Diptera: Dolichopodidae) from the Lower Cretaceous amber of San Just (Spain), and the co-occurrence of two ceratopogonid species in Spanish amber deposits, Zootaxa 1920, pp. 29-40 : 31-35

Microphorites utrillensis Peñalver , nov. sp.

Figs. 1–3 & Pl. 1, figs. a–c.

2006 Microphorites sp.; Peñalver et al.; fig. 1.

2007 Microphorites sp.; Delclòs et al.

2007 Microphorites sp.; Peñalver el al.; figs. 6D & 7. 2007 Dipteran Microphorites sp.; Delclòs & Soriano: fig. 4H.

Holotype: Adult female. Specimen CPT-963, housed in the Fundación Conjunto Paleontológico de Teruel- Dinópolis (Teruel Province, Spain). Complete specimen present in a transparent, clear piece of amber of 9 x 5 mm into an epoxy resin preparation of 15 x 9 x 2 mm. The specimen, along with other insects, is trapped within a spider orb web, which is the oldest web in the fossil record ( Peñalver et al., 2006).

Type locality: Specimen collected in San Just outcrop, in the municipality of Utrillas, near the village of Escucha (Teruel Province, Spain). Escucha Fm. (La Orden Member), Lower Cretaceous (Lower-Middle Albian). See Peñalver et al. (2007) and Delclòs et al. (2007).

Derivation of name: After Utrillas, the name of the municipality where the type locality is located.

Diagnosis: Distinghished from other female and male Microphorites by the following combination of characters: very short arista (shorter than basal flagellomere), scutellum with two pairs of strong apical setae, costal vein ends at apex of M1, R1 ends at a basal position with respect to m-cu crossvein, R2+3 ends in a medial position between the ends of R1 and R4+5, crossvein r-m at 2/5 of the wing length, dm-cu not arched and 3.5 times longer than m-cu, abdomen elongate (not short and compact).

Description: Body length 1.70 mm (from head to the evaginated distal part of the abdomen, see Fig. 1 & Pl. 1, fig. a). Head 0.25 mm long, 0.32 mm greatest width. Eye dichoptic (slightly separate in dorsal position), bare, not emarginated near antennae, diameter 0.20 mm, occupying entire lateral surface of head. Ommatidia uniform ( Fig. 2 & Pl. 1, fig. b). Postocular setae apparently absent. Three large ocelli in a narrow triangle without ocellar setae. Frons broad and face broader than frons. Clypeus bare. Proboscis relatively long, with abundant fine, long hairs apically. Palp short and one-segmented, flat, slightly longer than broad ( Fig. 2 ), 0.07 mm long and 0.04 mm wide, with short, fine hairs. Strong setae around mouthparts. Aristate antenna 0.26 mm long with fine, dense microtrichia. Scape reduced. Pedicel 0.04 mm long, 0.05 mm wide, with a ring of strong setae apically. Basal flagellomere subtriangular, bilaterally symmetrical, laterally compressed, elongate, basally swollen, 0.12 mm long, 0.04 mm greatest width, 0.05 mm greatest height. Arista apical and short, 0.10 mm long, and 2-articulated, basal article very small, slightly longer than width (0.01 mm long). Distal article 0.09 mm long.

Thorax 0.45 mm long. Proepisternum and prosternum bare. Few strong thoracic setae; scutum with two long, strong setae in a dorsal position and scutellum with two pairs of strong apical setae.

Wings 1.18 mm long, 0.44 mm wide, without a costal bristle, and only very slightly pointed at apex. Apart from the diagnostic venational characters the wing venation ( Fig. 3 a) shows a C with one row of spinules, a Sc parallel with R1 except for a short curved stem which apparently touches it apically (the connection with C is not visible; possibly distal part is evanescent, i.e., Sc vein incomplete), all longitudinal veins complete, an R4+5 unbranched and reaching very close to the wing apex, an M1 straight beyond crossvein dm-cu and flexed apically, a crossvein r-m short and near wing base, an m-cu vein tubular and inclined towards wing apex, a bm-cu crossvein complete, and a CuA2 curved. The veins are not setose, except C, and the crossvein h is obscured (not drawn in Figs. 1 & 3 a). Anal lobe not well developed.

Legs not modified and moderately bristly. Fore leg 1.00 mm long (femur 0.33 mm; tibia 0.35 mm; ta1 0.12 mm, ta2 0.06 mm, ta3 0.05, ta4 0.03 mm and ta5 0.06 mm). Mid legs difficult to measure (tarsus approximately 0.36 mm). Hind leg 1.02 mm long (femur 0.35 mm; tibia 0.32 mm; ta1 0.16 mm, ta2 0.06 mm, ta3 0.04 mm, ta4 0.03 mm and ta5 0.06 mm); tibia not clavate and first tarsomere of normal shape. Empodium apparently small or setiform, and pulvilli well-developed ( Fig. 3 b).

Abdomen telescoped, elongate, 1.14 mm long, 0.30 mm wide, with the terminalia extruded ( Fig. 3 c & Pl. 1, fig. c) (abdomen partially destroyed and impregnated with resin). Tergite 10 short (0.03 mm long and 0.03 mm wide), with sclerite apparently undivided, and without acanthophorite apical spines. Apical segments of the abdomen with long setulae (segment 10 with setulae only in the cerci). Cerci sclerotized (apparently heavily sclerotized), short (0.03 mm long), held horizontally, lateral in position, with at least four strong bristles each (up to 0.05 mm) and few setulae.

Discussion: This female specimen found in San Just Amber clearly belongs to the genus Microphorites Hennig, 1971 ( Dolichopodidae : Microphorinae ). It shows all the characters indicated by Grimaldi & Cumming (1999) in the translated and summarized diagnosis of Hennig (1971). It corresponds to a new microphorine species which differentiates from the four species found in the Early Cretaceous ambers from Lebanon [ M. extinctus , female ( Hennig, 1971), M. similis , female, M. oculeus , male ( Grimaldi & Cumming, 1999)] and France [ M. deploegi males and females ( Nel et al., 2004)]. It is closest to the last one mentioned.

Microphorites deploegi from Charente-Maritime ( France) was described from male and female specimens, but the female was not illustrated. ( Nel et al., 2004). The well preserved new female specimen of Microphorites discovered in San Just has been compared in the MNHN of Paris to two paratype females of M. deploegi (ARC 118-R and ARC 198.4-R). Female Microphorites utrillensis differs from female M. deploegi in having body that is graceful and smaller (1.7 mm long vs. ca. 2.0 mm), arista approximately as long as the flagellomere I (vs. approximately twice as long in M. deploegi ), wing approximately half long (1.2 mm vs. 2.2 mm in French specimen ARC 118-R), costal vein ending at the end of M1, abdomen not globular (1.1 x 0.3 mm vs. 0.8 x 0.4 mm), and fewer and finer setae on head, thorax and legs, with two pairs (vs. one pair) of strong apical setae on the scutellum. Interestingly, Microphorites utrillensis has cerci with very long apical setae as in extant genera Heteropsilopus and Microphor , among other dolichopodids (see Sinclair & Cumming, 2006, p. 46), an unlike M. deploegi which has short setulae. The male holotype of M. deploegi has the crossvein r-m spectral and m-cu evanescent (similarly in the female ARC 118-R), both of which are clearly tubular in the new species (like in the female ARC 198.4-R of M. deploegi ), and its Sc vein is different as well (curved back towards R1, closely parallel with R1 but not touching it, connecting C far from the end of R 1 in M. deploegi ). In contrast with the new species, a complete Sc connecting C is also present in fossil M. similis and M. oculeus , and in the extant Schistostoma (see Grimaldi & Cumming, 1999, figs. 37–38 and Sinclair & Cumming, 2006, p. 35). In M. extinctus Sc connects C but it is evanescent apically (see Hennig, 1971, fig. 21). Nel et al. (2004) did not indicate why males and females were put in the same M. deploegi species; apparently the specimens were found in different amber masses, but the co-occurrence in the same outcrop of several specimens which exhibit similar morphological characteristics suggests they are of the same species. The French males and females have the same antennal morphology and it is in agreement with the sexually dimorphic variation seen in the Microphorinae , which affects to other characters as was indicated by Grimaldi & Cumming (1999: 61). Nel et al. (2004) added to the diagnosis of the genus that the female tergite 10 bears no “acanthophorite” apical spines and that the female cercus is heavily sclerotized, held horizontally, bearing short setulae. The new specimen from San Just is the best known preserved female Microphorites and it is in a very clear amber mass, showing the terminalia extruded. This Spanish specimen confirms all the characters for the genus Microphorites added to the diagnosis by Nel et al. (2004), with the single exception that the cercus has long setulae.

The wing venation of the new species is very similar to those of Microphorites extinctus described by Hennig (1971) from Lebanese Amber, but differs mainly in having a different Sc vein, an R1 that ends at a basal position respect to m-cu crossvein, an R2+3 that ends more basally (in a medial position between the ends of R1 and R4+5), an m-cu vein inclined towards wing apex, a dm-cu not arched, and an elongate abdomen.

Microphorites utrillensis nov. sp. differs from M. similis , described by Grimaldi & Cumming (1999) on the basis of a female specimen from Lebanon Amber, mainly in having a different morphology of the basal flagellomere and a distal one that is very short in comparison, a shorter proboscis, a costal vein ending at apex of M1, a complete Sc, an R1 ending in a basal position respect to m-cu crossvein, an m-cu vein inclined towards wing apex, a dm-cu 3.5 times longer than m-cu, and an abdomen elongated with distinct terminalia.

Microphorites oculeus was described on the basis of a male specimen from Lebanon Amber by Grimaldi & Cumming (1999). This species is easily distinguished from all other known Microphorites , including the new species, by its longer and very abruptly tapered basal flagellomere with a strongly bulbous base and eyes occupying most of the head. Also differs from the new species in having clearly longer articles of the arista, a complete Sc and a costal vein ending at apex of R4+5.

Several male and female specimens of Microphorites are known from Álava Amber probably representing at least four different forms not yet described. Thus an important goal for future researches will be to elucidate if the species of San Just Amber is already know in the Álava deposit. Nel et al. (2004) provided an extensive discussion about the relationships of the family Dolichopodidae and the ¨ Microphorinae ¨ and ¨ Parathalassiinae ¨ groups, indicating the relevance of the genus Microphorites for the cladistic analysis. Recently, an extensive cladistic analysis of the Empidoidea and basal lineages of the Cyclorrhapha based on morphological characters has been published by Sinclair & Cumming (2006). That analysis has confirmed the monophyly of both groups and the authors included into Empidoidea the five families Empididae , Hybotidae , Atelestidae , Brachystomatidae and Dolichopodidae s.lat. Last, the family Microphoridae was not recognized, and the Microphorinae and Parathalassiinae were assigned to the Dolichopodidae s.lat. by the authors cited.

Figures

FIGURE 1. Camera lucida drawings of Microphorites utrillensis Peñalver nov. sp. (Dolichopodidae), female holotype (CPT- 963), in ventral and dorsal habitus, from San Just Amber (Teruel Province). Bar = 1 mm. See also Plate 1 a.

FIGURE 2. Camera lucida drawing of the head of Microphorites utrillensis Peñalver nov. sp. (Dolichopodidae), female holotype (CPT- 963), in ventral view. Bar = 0.1 mm. See also Plate 1 b.

FIGURE 3. Camera lucida drawings of the a) wing (crossvein h obscure), b) hind leg and c) distal part of the abdomen in ventral view. Microphorites utrillensis Peñalver nov. sp., female holotype (CPT- 963). cerc = cercus. All to the same scale (bar = 0.1 mm). See also Plate 1 c.