Protomedetera uncinata, Grootaert & Velde & Isabella Van de, 2024

Grootaert, Patrick, Velde, & Isabella Van de, 2024, New long-legged flies from mangroves on Pulau Ubin (Singapore) (Insecta: Diptera: Dolichopodidae), Raffles Bulletin of Zoology 72, pp. 303-323 : 319-321

Protomedetera uncinata , new species

( Figs. 16–18 )

Diagnosis. Small species with shiny metallic green head and thorax. Antenna yellow, but pedicel with almost black apex. Pedicel with 3 long marginal bristles covering the spheroid postpedicel. Anterior half uniformly covered with short bristles; 4-serial acrostichals indistinctly separated from dorsocentrals. Only the 2 prescutellar dorsocentral bristles long. All coxae and femora blackish brown, tibiae and tarsi yellow. Tip hypandrium very wide, forked, and dorsally bent. Surstylus lacking squamiform bristles. Cerci small, oval.

Etymology. The name uncinata (Lat. Feminine uncīnāta: bearing hooks) refers to hook-like bifurcate tip of the hypandrium.

Material examined. Holotype male. Singapore, Pulau Ubin , ( PU07 ) 16 March 2016, Malaise trap ( ZRCBDP0085280 in LKCNHM; leg. P. Grootaert). GenBank accession code: PP893312

Paratypes. SINGAPORE, female, ZRCBDP0081888 _12_ PU01 _ 10Aug2016; GenBank accession code: PP893313; female ZRCBDP0084331 _ PU01 _ 01Jun2016, GenBank accession code: PP893314; female ZRCBDP0084003 _ PU01 _07 Apr 201 (imaged), GenBank accession code: PP893315; female ZRCBDP0085270 _ PU04 _ 08Jun2016, GenBank accession code: PP893316; female ZRCBDP0085236 _ PU04 _ 07Apr2016, GenBank accession code: PP893317; female ZRCBDP0085235 _ PU04 _ 07Apr2016; GenBank accession code: PP893317; female ZRCBDP0085269 _ PU04 _ 01Jun2016 (Ma9036); GenBank accession code: PP893319; female ZRCBDP0085280 _ PU07 _ 16Mar2016 (mitogenome); ZRCBDP0083285 _ PU10 , GenBank accession code: PP893320; ZRCBDP0257071 _ PU19 _ 26Apr2018; GenBank accession code: PP893321; ZRCBDP0256595 _ PU19 _ 03May2018; GenBank accession code: PP893322; ZRCBDP0317777 _ PU24 _ 02Apr2019; GenBank accession code: PP893323 .

Male. Length: body 1.79 mm; wing 1.66 mm; wing width 0.55 mm.

Head. Frons and face shiny metallic green. Face triangular, wide below antenna, narrowing down to clypeus, there a little wider than pedicel; indented near middle with a furrow. Clypeus narrow. Hairs and bristles on head brownish. A pair of strong retroclinate ocellar bristles, a pair of strong proclinate vertical bristles ( Fig. 16 ) and a pair of short postvertical bristles pointing inward. Postocular bristles uniseriate, brown.

Antennae. Scape yellow, short, with an interior projection. Pedicel yellow, cup-like, large, with postpedicel sunken in it; in the apical crown of bristles 3 long apical bristles longer than and bending over the postpedicel; below the long ventral apical bristle a second a long finer bristle; with some additional short, scattered bristles, most at the inner side. Postpedicel with apex dark brown, spheroid, with short pubescence and a subapical long arista (shifted toward outside). All bristles on postpedicel brown. Arista 3 times as long as all antennal segments together; black, naked, basal portion of arista short. Palpus brown, small, circular, with a long brown subapical bristle, and a second bristle beneath.

Thorax. Brownish metallic (pollinosity probably absent, not visible in the ethanol conserved specimen). Basal half of mesonotum uniformly covered with short bristles, the rows of 4 serial acrostichals indistinctly separated from dc. Apical half of mesonotum flat before scutellum, lacking bristles in central area. Hairs and bristles on thorax brownish black; 2 long prescutellar dorsocentral bristles, anterior dorsocentrals short followed by 2 long prescutellar dorsocentrals. A pair of very long crossing scutellars with a short bristle at outside.

Legs. Mainly brown but trochanters, tip of all femora, all tibiae and tarsomeres yellow except tarsomere 5 of all legs brownish. Hairs and bristles on legs brownish black.

Fore legs. Coxa densely covered with short pale bristles, long apical bristles; one bristle in middle longer than the others. Fore femur with short pale ventrals and no distinct posterior preapical bristles. Tibia with short apicals.

Mid legs. Coxa with short anterior bristles and a long pale brownish exterior bristle as long as coxa is long. Femur with a fine preapical anterior bristle. Tibia with a short anterodorsal and a longer posterodorsal near base; a stronger anterodorsal at ⅓ of base and a small anterodorsal in preapical crown; ventral preapical twice as long as width of tibia.

Hind legs. Coxa with a short brownish exterior bristle near middle. Femur in apical half with a row of short brown anteroventral bristles; preapical anterior bristles indistinct. Hind femur with indistinct preapical bristles. Hind tibia lacking distinct bristles, apart from the short bristles in apical crown.

Wings. Hyaline, tinged yellowish grey. Veins yellowish brown. Squama white, with a single short brown bristle. Haltere white.

Abdomen. Brown.

Male terminalia. Fig. 18 . Foramen situated at base of epandrium. Surstylus brown, wide truncate composed of a single element supposed to be the dorsal surstylus. Apex surstylus rounded with 3 short and 3 long bristles on the ventral side, and 2 strong subapical bristles on the lateral side ( Fig. 18B ). Cercus short oval, with a short and a very long apical bristle ( Fig. 18B ), other bristles short ( Fig. 18C ). Hypandrium bifurcate ( Fig. 18A ), the fork bent dorsally ( Fig. 18B ). Phallus hidden below hypandrium. Apicoventral epandrial lobe lacking, but 3 almost equally long epandrial bristles present.

Female. Length: body 1.55–2 mm; wing 1.64–2.2 mm. In most aspects, resembles male as there are no secondary sexual characters.

Comments. Variability is noted in the darkening of the postpedicel from brown with a paler base to almost black apex. Protomedetera uncinata , new species, differs from all other known Protomedetera by the strong forked tip of the hypandrium. The forks are bent dorsally.

National distribution. Thanks to the barcoding, 13 specimens were identified. Protomedetera uncinata , new species, is the most abundant Protomedetera species ever found in Singapore; it is exclusive to Pulau Ubin. All the records are from back mangroves, except for a single record from a coastal forest (PU26). This site is very close to a back mangrove, so sample contamination could have occurred during flooding of the area by a storm and a spring tide.

Other Protomedetera species. Two more unidentified species of Protomedetera were found on Pulau Ubin.

1. A female of Protomedetera with quadriserial acrostichal bristles, 4 long dorsocentrals, and yellow hind metatarsus was found in station PU01 on 19 March 2019 (labelled sp4). It seems to be different from the other three species reported above. Unfortunately, no barcode is available yet to give an indication if it might belong to another species.

2. A female, provisionally labelled as sp5 (PU01, ZRCBDP0083912, image on BOS: https://singapore. biodiversity.online/species/A-Arth-Hexa-Diptera-002292) has the proboscis as long as head is high, which is unusually long for Protomedetera . It has 2 long dorsocentrals, but since the specimen was severely damaged, some dorsocentrals may have been lost. The basal tarsomere of the hind tarsus is slender and longer than the following tarsomere, which is also unusual for Protomedetera . Since the specimen was destroyed during extraction for sequencing, no nomenclatorial actions can be taken. The mitogenome was successful and the species clusters at the outside of the other Protomedetera . Following barcode is available (courtesy of Darren Yeo): ZRCBDP0083912 sp5 PU01, GenBank accession code: PP893324.

3. A female belonging to the P. glabra group was found in a strip of secondary forest in front of Endut Senit Campsite ( PU12 , ZRCBDP0281845 _ PU12 _ 22Mar2018, GenBank accession code: PP893325 ) .

As already mentioned above, P. glabra has different morphology from the type species of Protomedetera and should probably be attributed to another genus. The postpedicel does not bear long apical bristles and the position of the male terminalia on the abdomen is different. Protomedetera glabra Tang et al., 2018 was found in Papua New Guinea (holotype) and in Singapore, but although the male terminalia of the specimens from Papua New Guinea and those from Singapore are similar, they are distinctly different and hence the taxonomy of this species group needs revision. The species was generally found in anthropogenic habitats, like Clementi Woods (park), Evolution Garden (Botanic Gardens), NUS (university park), and Sime Forest.

Comments on Protomedetera in Pulau Ubin. The genus Protomedetera is very rare in Singapore and although many sites and various biotopes were surveyed during the last twenty years for prolonged periods, only two species were recorded in the past ( Tang et al., 2018). With six species now, Pulau Ubin seems to be a hot spot for the genus Protomedetera . It is unclear what the reason might be. On Pulau Ubin, all species were found in mangrove areas or very close to mangroves. Protomedetera is a tree trunk dweller, but its precise biology is unknown. The presence of lots of dead decaying wood present at the surveyed sites might favour the presence of Protomedetera , where it might feed on wood inhabiting insects like the related genus Medetera .

Figures

Fig. 16. Protomedetera uncinata, new species, male habitus (ZRCBDP0085280). Photograph by Kristy Chang.

Fig. 17. Protomedetera uncinata, new species, female habitus (ZRCBDP008400). Photograph by Kristy Chang.

Fig. 18. Protomedetera uncinata, new species, male terminalia. A, Ventral; B, Lateral; C, Dorsal. Scale bar = 0.1 mm. Drawings by P. Grootaert.