Stratiomys reducta, Nerudová & Kovac & Rozkošný, 2007

Nerudová, Jana, Kovac, Damir & Rozkošný, Rudolf, 2007, Description Of The Oriental Stratiomys Reducta, New Species, And Its Larva And Puparium (Diptera: Stratiomyidae), Raffles Bulletin of Zoology 55 (2), pp. 245-252 : 246-251

Stratiomys reducta , new species

( Figs. 1–7 )

Material examined. – Holotype: male, north Thailand, Mae Hong Son Province, Pangmapa District: near Muang Phaem, 18 Apr.2002, 1 male ex puparium of larva found in spring, A87/02, coll. D. Kovac, deposited in the Senckenberg Forschungsinstitut, Frankfurt am Main ( SMF).

Paratypes: 1 female, same data as holotype, A87/02, ( SMF) ; 1 female, same locality, 07 Apr.2002, resting on grass, A74/02 ( SMF) ; 1 female, same locality, 7 Apr.2002, ex puparium, A84/02 ( SMF) ; 1 female, same locality, 17 Apr.2002, ex puparium, A85/02 ( SMF) ; 1 female, same locality, 18 Apr.2002, ex puparium, A86/02 ( SMF) ; 4 females, same locality, 20 Apr.2002, ex puparia, A88/02 (1 specimen in SMF, 1 specimen in Faculty of Science, Masaryk University ( FSMU), 2 specimens in the Department of Entomology, Kasetsart University , Bangkok) ; 1 male, same locality, 22 Apr.2002, ex puparium, A96/02 ( FSMU) .

Larvae : 66 larvae, same locality as holotype, 7 Apr.2002, A75/02– A81/02 ( SMF) ; 7 larvae, same locality and date ( FSMU) ; 2 larvae, near Ban Huai Pong , 15 Oct.2005 ( SMF) . All specimens collected by D. Kovac.

Etymology. – The proposed name refers to the reduction of lateral abdominal markings in both sexes compared to related species.

Description. – Holotype male: Head suboval in lateral view, tapered towards prominent ocellar tubercle. Face somewhat convex but narrowly produced in lateral view, postocular rim swollen in lower third. Eyes bare, medially contiguous for a long distance, facets markedly smaller in lower third. Lower frons above antennae subshiny black, face also entirely black but more punctuate and finely wrinkled. Antenna long, flagellum with 5 flagellomeres, apical flagellomere dull, relative lengths of scape: pedicel: flagellum are 2.6: 1: 4. Head pilosity whitish-yellow, erect and fairly long especially on swollen area of postocular rim but very short and appressed on occiput behind eyes.

Thorax black, only scutellar spines and narrow space between them yellow. Thoracic pile woolly, longer and dense along notopleura and on pleura. Wing hyaline, with brownish veins and slightly bronze tinge. Wing venation as in other species of genus, all M veins ending far before wing margin, Cu 1 A somewhat longer, postcubitus hyaline but distinct. Lower calypter haired, with usual fan-like process.

Legs predominantly black, only fore- and mid-knees yellowish; basal third of hind tibia contrastingly yellow. Mid and hind basitarsi pale brown to yellow. Pile on legs inconspicuous, pale and mostly appressed, longer and more reddish on inner surface of fore tibia.

Abdomen ( Fig. 1 ) rounded, broader than thorax, predominantly black. Yellow pattern consisting of narrow markings at posterior corners of tergite 3 and narrow lateral margin of tergite 4. Similar spots at posterior corners of tergite 2 barely visible and lateral margin of tergite 3 very narrowly yellow only at anterior corner. Posterolateral spots on tergite 4 mostly absent but a small subtriangular medial spot visible near posterior margin. A narrow longitudinal medial stripe on tergite 5 not reaching its anterior margin and partly extended along posterior margin.Venter predominantly black, sternites with yellow posterior and lateral margins; sternite 1 yellow medially; yellow pattern on sternite 2 extending almost to its anterior margin and occupying more than medial third. Abdominal pile black, short and appressed on dark parts of tergites. Pale hairs nearly erect at anterolateral corners of abdomen, short and denser on lateral margin of two last tergites. Ventral abdominal pile entirely pale, inconspicuous.

Male genitalia ( Figs. 2–4 ): Epandrium convex, posterior margin transverse, emarginate anteriorly. Proctiger resembling a low triangle, cerci subquadrate, posterior margin slightly obliquely transverse with slightly produced posteromedial lobe. Genital capsule ( Fig. 3 ) massive, with a well-developed medial process with a slightly bilobed posterior margin, gonostyli sharply pointed medially and gonocoxal apodemes not reaching anterior margin of genital capsule. Aedeagal complex ( Fig. 4 ) only slightly longer than genital capsule at midline, smooth and tripartite; lateral lobes dilated in distal third.

Measurements. – Length: body (without antennae) 7.5 mm, wing 6.6 mm.

Female. – Eyes bare, head with a broad frons occupying more than 1/3 of head width, ocellar tubercle prominent in lateral view ( Fig. 6 ). Frons slightly widened towards antennae, predominantly black and densely punctate but punctation somewhat reduced on vertex. Two distinct, transversely oval, shiny frontal calli present above supra-antennal depression, both predominantly black but each with a narrow and medially-widened yellow spot ( Fig. 7 ). Area around bases of antennae black and black pattern narrowly extending along frontal depression and continuing as broad medial stripe on face. Scape and flagellum of antenna relatively longer than in male, relative lengths of scape: pedicel: flagellum are 3.5: 1: 4.6. Oral margin broadly black with black colouration continuing on gena below eye. Postocular rim band-shaped, almost as broad as length of pedicel, parallel sided, contrasting yellow and continuing on posteroventral margin of eye. Median occipital sclerite with a pair of large yellow spots, upper margin of occipital cavity yellow, remainder black. Head pile rather short, semi-erect to erect, pale but more brownish on upper frons, very short, dense and appressed especially on postocular rim.

Thorax, wings and legs as in male but nearly the entire posterior half of scutellum pale and basal thirds of all tibiae yellow. Abdominal spots on tergite 3 slightly narrower than in male, yellow lateral margins on tergites 3 and 4 slightly more extensive and yellow medial stripe on tergite 5 longer ( Fig. 5 ). Venter more extensively yellow: posterior margin of sternite 1 entirely yellow and yellow posterior margins of sternites 3 and 4 broadened medially. Female genitalia not examined.

Measurements. – Length: body (without antennae) 8.62 – 10.53 mm, wing 5.92 – 8.16 mm. 9 females examined.

Larva (mature). – Elongate, only slightly dorsoventrally flattened, caudal end distinctly tapering, anal segment modified into an elongate breathing tube. Head mostly dark brown. Dorsomedian sclerite separated by a clypeofrontal suture on either side, dark brown with paler proximal third. Lateral sclerites (genae, ocular plates) predominantly medium brown. Ventral sclerites uniformly dark brown with black margins. Oral opening and antennae black, at least basally. Dorsum of body segments mainly brown in ground colour, with dark brown and yellowish pattern. Thoracic segment 1 uniformly brown on anterior half; posterior half with yellow pattern consisting of small circular, partly confluent yellow spots. Central area yellow with a dark longitudinal midline. Also, extensive lateral areas around anterior spiracles yellow. Thoracic segments 2 and 3 more yellow than preceding, with three pairs of subquadrate yellow patches in a transverse row at anterior margin. Area on about posterior 2/3 of segment with yellow circular spots which are, however, more confluent than on thoracic segment 1, thus a dark medial line is visible along entire length. Abdominal segment 1 with six well developed yellow patches along anterior margin, posterior part of this segment with a similar pattern as on thoracic segment 3, although apparently darker. The following abdominal segments with six (= three pairs) subtriangular yellow patches along posterior margin, middle pair larger than others. Lateral areas of abdominal segments with extensively confluent yellow spots creating a brownish pattern with more or less distinct longitudinal stripes. Venter of body segments yellowish-brown in ground colour. Thoracic segments with several small brownish spots arranged into posteromedial and lateral symmetrical groups. Brownish spots on abdominal segments not very distinct, more confluent ventrolaterally, forming two more or less distinct longitudinal stripes on each side.

Head ( Figs. 8–10 ; 13–17 ): only slightly retracted into thoracic segment 1, about as long as broad in dorsal view, head index 1.0–1.2. Labrum somewhat longer than anterolateral corners of head capsule. Eyes distinct but small, darker than surrounding areas. Two-segmented antennae situated at the anterolateral angles of the head capsule (a, in Fig. 13 ). Basal segment of antenna about twice as long as wide, apical segment short, semiglobular. One relatively small dark brown subcylindrical sensilla visible beside apical segment (se, in Fig. 17 ). Ventral margin of genal lobes bordered by dense hair fringe. Mandibular-maxillary complexes located on the sides of labrum densely haired, transverse rows of flat setae arranged in characteristic combs in apical part. Fingerlike maxillary palpus relatively long. Ventral opening of head capsule well-developed, covered with fine membrane.

Body segments: Larval body consists of three thoracic and eight abdominal segments. Thoracic segments almost as long as wide. Abdominal segments gradually tapering and elongated toward distal end: segments 1–3 more than twice as wide as long, segment 5 subquadrate, segment 7 almost 1.5 (1.4) times as long as wide and anal segment about four times as long as wide (index of mature larvae 3.6–4.3). Oval anal slit located near base of anal segment occupying less than one-third of segment length ( Figs. 12 , 22 ). No ventral hooks and intersegmental projections visible; sternal patch not present.

Respiratory system: Dark brown anterior spiracles on sides of thoracic segment 1 relatively small, oval ( Fig. 18 ). Very small and indistinct, circular, dark brown dorsolateral spiracles found on thoracic segment 3 and abdominal segments 1–7 that are very probably non-functional. Tranverse spiracular opening at distal end of anal segment surrounded by pinnate float hairs arising from dorsal and ventral lips ( Figs. 12 , 22 ).

Chaetotaxy (for definitions of terminology see Rozkošný, 1982): Configuration and number of major setae same as in other species of the genus Stratiomys . Head capsule virtually without surface hairs (except for conspicuously haired genal lobes on ventral side and anterior margin of ventral opening), major setae clearly visible. Labral setae (Lb 1) relatively long and simple, posterior labral setae (Lb 2) broadly bushlike ( Figs. 8, 9 ). Anterior clypeofrontal setae (Cf 1) on level of posterior eye margin, simple and slender, posterior clypeofrontal setae (Cf 2) fanlike with numerous branches ( Figs. 8, 9 , 13 ). Long and slender dorsolateral seta (DL) beyond eye and lateral seta (L) just below it ( Figs. 8, 9 , 15 ). Three pairs of ventral setae well-developed. Seta V 1 close to ventral opening, largely fanlike and transverse with numerous branches but often almost invisible among marginal hairs of genal lobes, setae V 2 relatively long and simple, V 3 setae simple, flattened in basal half ( Figs. 9, 10 , 15 ). Ventrolateral setae arranged into elongate triangle: Vl 1 in middle of genal lobe, Vl 2 between lateral seta (L) and antenna, and VL 3 in front of V 3 ( Figs. 9, 10 , 15 ).

Major setae on body segments often barely visible among long pale hairs that are especially dense on anterior half and dorsolateral parts of segments.

Thoracic segment 1 bears all characteristic setae including 2 pairs of anterodorsal (Ad) and 3 pairs of dorsal setae (D). All setae simple, at most with short pubescence, Ad1 and D 1 setae partly flattened. Slender and long D2 setae shifted to anterior margin of segment ( Figs. 8 , 19 ). Dorsolateral (DL) and ventrolateral (VL) setae hardly visible between bunches of numerous, long setae forming lateral fringe. Ventral side with only short two-branched outer ventral setae (V 2) and simple, short inner ventral setae (V 1) inserted more medially and slightly anterad. Dense pale short hairs present on almost entire anterior half of segment. Remaining pubescence sparse, hyaline, denser only along lateral margins.

Setae on dorsal and ventral side of thoracic segments 2 and 3 in same position as on segment 1, but without anterodorsals. Dorsal setae D1 and D 3 in a transverse line, D2 setae again shifted anteriorly.

Configuration of dorsal setae on abdominal segments 1–7 very similar to thoracic segments 2 and 3; dorsal D 1 setae pubescent, D 2 setae again shifted anteriorly approximately at boundary of anterior third of segments, D 3 inserted at same level as D 1 ( Figs. 11 , 20, 21 ). Relatively short dorsolateral seta (DL) inserted above spiracle on each side. Two major lateral setae (L 1, L 2) often barely distinct among hairs on lateral margin but L 2 usually longer ( Fig. 11 ). Three pairs of ventral setae arranged semicircularly: (V 1) located closest to posterior margin, V 2 being somewhat above and more lateral and V 3 above them, near anterior margin ( Fig. 12 ). On dorsal side of anal segment (= abdominal segment 8) one pair of short dorsal setae present at distal third and two pairs of relatively long lateral setae: L1 above middle of segment and L 2 at each posterolateral corner ( Fig. 11 ). Ventral side with 6 pairs of setae being more or less distinct (V 1 above anal slit, V 2 more lateral at level of proximal end of anal slit, V 3 at sides of anal slit, V 4 at level of distal end of anal slit, V 5 and V6 approximately at the middle of segment ( Figs. 12 , 22 ). Pair of apical setae (Ap) distinct on ventral side just above apical coronet. Subapical setae were not found ( Fig. 12 ).

Measurements. – Length 9.0– 27.3 mm; maximum width 1.3–4.0 mm. Seven larvae examined.

Puparium. – The pupa is formed within the skin of the last larval instar. All morphological structures characteristic for the last instar larvae including mouthparts, cuticular structures and surface pubescence remain unmodified. In full agreement with the other known larvae of the Stratiomyini no pupal structures (elongation of anterior spiracles or pupal respiratory tubes on abdominal segments) were present on the surface of the puparium. The length and maximum width of the puparium is the same as in mature larvae.

Measurements. – Length 25.6–27.1 mm; maximum width 3.6–4.1 mm. Two puparia examined.

Biology. – Stratiomys reducta larvae were found at two different localities, near the settlements of Muang Phaem and Ban Huai Pong. Both collection sites were situated in an open area of the forest with water diffusely seeping out of the ground ( Fig. 23 ). In the depressions of the wet ground there were small puddles. Most larvae stayed in the puddles, but some were also creeping around on the wet ground between them. The larvae were most abundant in March–April (dry season). There were hundreds of larvae at the Muang Phaem site, while at the Huai Pong site there were only a few. The reason for the high abundance of S. reducta larvae at the Muang Phaem site is probably the regular occurrence of water buffaloes ( Fig. 23 ). The water buffaloes create depressions in the ground when walking around and their dung provides additional nutrients for the organisms living in the puddles.

Figures

Figs. 1–7. Stratiomys reducta, new species. Characters of adults: 1, male abdomen, dorsal view; 2–4, male genitalia: cerci, proctiger and epandrium (2), genital capsule (3), phallic complex (4); 5, female abdomen, dorsal view; 6, female head, lateral view; 7, female head, frontal view, antennae removed.

Figs. 8–12. Stratiomys reducta, new species. Mature larva: 8, head and thoracic segment 1, dorsal view; 9, head, lateral view; 10, head,ventral view; 11, last three abdominal segments, dorsal view; 12, last three abdominal segments, ventral view. Ad1, Ad2, Ap, Cf1, Cf2, D, Dl, D2, D3, DL, L, L1, L2, Lb1, Lb2, V1, V2, V3, V4, V5, V6, VL1, VL2, VL3 = constant setae.

Figs. 13–18. Stratiomys reducta, new species. Mature larva: 13, head, dorsal view; 14, clypeofrontal setae (Cf2) on dorsal side of the head; 15, head, lateral view; 16, head, ventral view; 17, antenna with sensilla; 18, anterior spiracles on sides of thoracic segment 1. a = antenna; se = sensilla; Cf1, Cf2, DL, L, V2, V3, VL1, VL2, VL3 = constant setae.

Figs. 19–22. Stratiomys reducta, new species. Mature larva: 19, thoracic segment 1, dorsal view; 20, abdominal segment 1, dorsal view; 21, abdominal segment 7, ventral view; 22, abdominal segment 8 (anal segment), ventral view. Ad1, Ad2, D1, D2, D3, V1, V2, V3, V6 = constant setae.

Fig. 23. Habitat of Stratiomys reducta, new species, in north Thailand (Muang Phaem site, April 2003).