Review of the Mesovelia horvathi species complex (Hemiptera: Gerromorpha: Mesoveliidae), with the description of seven new species from India Jehamalar, E. Eyarin Chandra, Kailash Polhemus, Dan A. Zootaxa 2019 2019-08-06 4651 3 471 496 427GS Lundblad, 1933 Lundblad 1933 [151,588,837,864] Insecta Mesoveliidae Mesovelia Animalia Hemiptera 2 473 Arthropoda species horvathi  ( Figs. 1A–F) 1933.  Mesovelia horvathiLundblad, Arch. Hydrobiol. Suppl. ,12, 190.   Material examined.   INDONESIA, SUMATRA,  Sumatera Utara Province,2 apt. ♂, 1 apt. ♀, Kab. Simalungun, Kec. Jorlan Hataran, swift river above Tigadolok, 18 kmE. of Prapat,  1000 ma.s.l., vic. 2.76750 0S, 98.98889 0E,  8.xi.1985, CL 2189, D.A. Polhemus& J.T. Polhemus( BPBM); 1 apt. ♂, Kab. Tapanuli Tengah, Kec. BarusUtara, swift rocky hill stream in primary lowland rainforest,  15 kmNW of Barus on Pakkatto Barusroad,  150 ma.s.l., vic. 2.08833 0S, 98.46583 0E,  10.xi.1985, CL 2194, D.A. Polhemus& J.T. Polhemus( USNM, BPBM).  Bengkulu province, 1 apt. ♀, Kab. Rejang Lebong, Kec. Birmani Ulu, Hutabarna Riverat Tabarenah, 7 kmW. of Curup,  600 ma.s.l., 3.44000 0S, 102.5097 0E, water temp. 23.5° C.,  7.ix.1991, CL 2582, D.A. Polhemus& J. T. Polhemus( BPBM).  Redescription. Apterous male: ( Figs. 1A–F). Body length 2.24 (2.20–2.40, n=3), body width at metanotum 0.60, body width at tergum IV 0.60 (n=3).  Colour. Yellowish brown; dorsum of body covered with minute pale setae; antenna yellowish brown; rostrum yellowish brown with apex of fourth article darkened; legs including tarsi and claws uniformly yellowish brown; setiform spines on appendages black.  Structural characters.Frontoclypeal region with 6–8 thick setae. Head length 0.55, head width across eyes 0.45; synthlipsis (minimum interocular distance) 0.20; eye length 0.20, eye width 0.10. Lengths of antennomeres I–IV 0.45, 0.30, 0.80, 0.75. Pronotal length 0.17, width 0.55; mesonotal length 0.15, width 0.56; metanotal length 0.10, width 0.55. Lengths of leg segments: foreleg: femur 0.70, tibia 0.65, tarsomeres I–III 0.03, 0.05, 0.09; mid leg: femur 0.80, tibia 0.90, tarsomeres I–III 0.04, 0.15, 0.11; hind leg: femur 1.10, tibia 1.55, tarsomeres I–III 0.05, 0.21, 0.15. Widths of fore, mid, hind femora 0.10, 0.10, 0.12. Flexor region of all femora lacking subapical spines; hind tibia sparsely clothed with medium sized spines on flexor margin, bearing 5–6 longer dark spines along extensor margin. Dorsal abdominal length 1.23; terga I–VIII 0.15, 0.15, 0.10, 0.10, 0.15, 0.13, 0.20, 0.30; sterna IV–VIII 0.10, 0.10, 0.14, 0.15, 0.12. Combined length of abdominal sterna V–VII 0.40. Basal region of sternum VIIIsublaterally with pair of dark brown spiniform setal tufts, each tuft with 6–7 spiniform setae arranged irregularly ( Fig. 1C); sternum VIIImidlaterally at level of posterior margin with very small tubercle (more evident in alcohol after dissection); inner length of spiniform setal tuft on sternum VIII0.09, basal width 0.04, width between two tufts 0.11; without any space between posterior margin of abdominal sternum VII and anterior margin of spiniform setal tuft. Terminalia: anterior part of proctiger longer than bowl-shaped posterior part, clothed with long setae posteriorly, posterior part ventromedially convex, not excavated, median lateral process long, with acute tip ( Fig. 1D); paramere slightly broad basally, medially not twisted, apical part tapering, gently curved on ventral margin ( Fig. 1E), paramere, when attached to pygophore, with apical part slightly curved and directed laterad in lateral view ( Fig. 1E) and in dorsal view tip directed anterad ( Fig. 1D).  Apterous female.Colour: similar to apterous male. Body length 2.60 (2.30–2.60, n=2), width across metanotum 0.70, width across tergum IV 0.90 (0.85–0.90, n=2), head length 0.55, head width 0.52, eye length 0.19, eye width 0.13, synthlipsis 0.25; lengths of antennomeres I–IV 0.45, 0.35, 0.76, 0.75; pronotal length 0.20, width 0.60, mesonotal length 0.15, width 0.65, metanotal length 0.10, width 0.68. Lengths of leg segments: foreleg: femur 0.65, tibia 0.70, tarsomeres I–III 0.03, 0.06, 0.10; mid leg: femur 0.90, tibia 0.87, tarsomeres I–III 0.03, 0.15, 0.11; hind leg: femur 1.05, tibia 1.60, tarsomeres I–III 0.05, 0.25, 0.20. Widths of fore, mid, hind femora 0.08, 0.11, 0.14. Flexor regions of fore and mid femora subapically lacking spines. Dorsal abdominal length 1.46, lengths of abdominal terga III–VIII, 0.50, 0.15, 0.15, 0.20, 0.22, 0.20; proctiger 0.14, dorsal gonoplac length 0.07, abdominal sterna V–VII, 0.13, 0.13, 0.15, abdominal length from sternum VIIIto abdominal tip 0.62; combined length of abdominal sterna V–VII 0.41; maximum connexivum width at tergum V 0.25, ventral abdominal length from sternum V to abdominal tip 1.10.  Distribution. Australia, Indonesia, Papua New Guinea, Japan, China, Indonesia, Malaysia, Myanmar, Philippines, Singapore, Taiwan, Cambodia, Thailandand Vietnam(J. Polhemus & D. Polhemus 2000, Damgaard et al. 2012, D. Polhemus 2017).  Type repository.Male and female syntypes( Damgaard et al.2012) ( Lectotypenot designated): Indonesia, Java, Ranu Lamongan and Ranu Pakis and Sumatra, Lake Ranau, Naturhistoriska Riksmuseet (Natural History National Museum) ( NHRS), Stockholm, Sweden.  Remarks.  Mesovelia horvathiwas described by Lundblad (1933)from a set of four syntypes, consisting of a female specimen taken at Lake Ranau in southern Sumatra(the modern Sumatera Selatan Provinceof Indonesia), and three additional specimens from Java, consisting of a male from Lake Lamongan, and a male and a female from Lake Pakis, both of these being crater lakes lying immediately to the east of Klakah in eastern Java. At the Lake Lamongan locality, the specimen was noted as having been taken amid aquatic plants, whereas at Lake Pakis the specimens were taken from moss. In the original description, Lundblad compared his species with  M. orientalisKirkaldy, 1901, i.e., the currently valid  Mesovelia vittigeraHorváth, 1895, and mentioned that the legs of both species were very similar, with the difference being that the middle leg in  M. horvathilacked ventral spines. Lundblad's discussion would thus imply that in  M. horvathithe fore leg might possess 5–7 ventral spines as in  M. vittigera.However, his figures 72 C and D clearly indicate the absence of such spines on both the fore and hind legs ( Lundblad 1933). This confusion about the presence or absence of dark spines, and their number, on the flexor region of the fore femur has not been noted in subsequent work on the genus ( Thirumalai 1989, 1994, J. Polhemus & D. Polhemus 2000, Andersen & Weir 2004, Chen et al.2006, Yang & Murphy 2011, Chandra & Jehamalar 2011, Jehamalar & Chandra 2016, Basu et al.2016, 2018). In the present study, the third author examined three apterous males and two apterous females of  M. horvathifrom Sumatera Utaraand Bengkuluprovinces of Sumatra. All of these specimens lack spines on both the fore and mid femora, and conform in all respects to the illustrations of  M. horvathiprovided by Lundblad (1933). As such, they form the basis for our interpretation of this species. Lundblad did not explicitly designate a holotypefor  M. horvathi, and no lectotypehas been designated to date. Because we have not seen Lundblad's specimens, and therefore cannot evaluate their condition, we defer from doing so here. A molecular analysis undertaken by Damgaard et al.(2012), which included sequence data from specimens of  M. horvathitaken in Australia, New Caledonia, Papua New Guinea, and Laos, indicated a modest degree of sequence divergence among the populations grouped under this species name, and subsequent study may reveal that cryptic species are also present in these regions. In particular, in the analysis of Damgaard et al.(2012), the populations from New Caledoniaand New Guineaclustered as a clade sister to those from Laosand Australia. J. Polhemus & D. Polhemus (2000)noted that a similar but undescribed species with a differing male paramere morphology was present on Ceylon, and that populations fitting within the broad species concept were also present in Africa, although they speculated that the latter might eventually prove to represent a separate species. In regard to the populations occurring west of Indochina, these authors concluded that “…the westernmost range of  M. horvathithus remains unclear, pending further analysis of these peripheral populations.”   FIGURES 1A–F.  Mesovelia horvathiLundbladapterous male: A, habitus, dorsal view; B, dorsal view of legs; C, eighth abdominal segment, lateral view; D, genital capsule, dorsal view; E, same, lateral view; F, fore femur, ventral view (dmp—dorsome-dian projection of pygophore; lex—lateral excavation; lp—lateral process; pa—paramere; pr—proctiger; py—pygophore). Our current morphological analysis indicates that many of the populations of the  M. horvathicomplex present on the Indian subcontinent represent a set of distinct species, as described herein. A more critical morphological assessment of material from Misool and Sumba islands in the eastern Malay Archipelago now indicates that those populations are also distinct from nominate  M. horvathi,but this problem will be addressed in a subsequent study. The previous few records of  M. horvathifrom Indiaby Thirumalai (1989, 1994), Chandra & Jehamalar (2011), Jehamalar & Chandra (2016), and Basu et al.(2016, 2018) may belong to one of the species described here, or other new species. The present study thus suggests that  M. horvathimay not have the wide distribution currently ascribed to it, and that previous records of this species from Australia, Borneo, Papua New Guinea, Japan, China, Indonesia, Malaysia, Myanmar, Philippines, Singapore, Taiwan, Cambodia, Thailandand Vietnamby J. Polhemus & D. Polhemus (2000), Damgaard et al. (2012), and D. Polhemus (2017)should be carefully re-examined. We have plotted the distribution of reliably confirmed populations of this species from Java and Sumatra in Fig. 10C. We consider it likely that “true”  M. horvathimay eventually be shown to be endemic to the Greater Sunda Islands. 2313474695 1985-11-08 BPBM D. A. Polhemus & J. T. Polhemus Indonesia 1000 Prapat Tigadolok 2 473 2 1 1 Sumatera Utara 2313474691 1985-11-10 USNM, BPBM D. A. Polhemus & J. T. Polhemus Indonesia 150 Barus Barus 2 473 1 1 Sumatera Utara 2313474678 1991-09-07 BPBM D. A. Polhemus & J. T. Polhemus Indonesia Hutabarna River 600 Curup Tabarenah 2 473 1 1 Bengkulu 2313474680 NHRS Sweden Lake Ranau 3 474 1 Stockholm