Mangalcoris miniatus, Murphy & Polhemus, 2012

Murphy, D. H. & Polhemus, Dan A., 2012, A New Genus Of Micropterous Miridae From Singapore Mangroves (Insecta: Hemiptera: Heteroptera), Raffles Bulletin of Zoology 60 (1), pp. 109-115 : 110-114

publication ID	https://doi.org/ 10.5281/zenodo.5347090
persistent identifier	https://treatment.plazi.org/id/227E87D0-E046-FFB9-FCEE-FC34FA4DF997
treatment provided by	Tatiana
scientific name	Mangalcoris miniatus
status	new genus, new species

Treatment

Mangalcoris miniatus View in CoL , new genus, new species

( Figs. 1–4 View Fig View Fig View Fig View Fig )

Type material. — SINGAPORE: Holotype male, Mandai Kechil mangroves, under intertidal wood at 2.6 m above datum, near abandoned house, under trees, 9 Apr.1990, coll. D. H. Murphy ( ZRC) . Paratypes (adults only) – SINGAPORE: 4 males, 7 females, 32 immatures, same data as holotype, D. H. Murphy ( ZRC, BPBM) . THAILAND: 2 males, 1 female, Ranong mangroves, in Rhizophora timber on ground, 14 Nov.1987, coll. D. H. Murphy ( ZRC) ; 1 female, Ranong, 28 Jul.1988, coll. D. H. Murphy ( ZRC) .

Diagnosis. — This species may be recognised by its micropterous form ( Figs. 1 View Fig , 2 View Fig ), red colouration ( Fig. 1 View Fig ), the shapes of the male parameres ( Figs. 2D, E View Fig ; 3A, B View Fig ), and its preference for intertidal mangrove habitats.

Description. — Micropterous male: Body form short and relatively broad, length 1.65, maximum width (across basal abdomen) 0.60; wings micropterous, appendages slender ( Figs. 1A, B View Fig ; 2B View Fig ); general colouration bright red ( Fig. 1A, B View Fig ).

Head short, declivant, length 0.30, width 0.40; antennae with all segments long, segment I stout, segments II–IV longer, more slender ( Figs. 1B View Fig ; 2B View Fig ), segments III and IV finely annulate, bearing erect setae with lengths 3× the diameter of these respective segments, lengths of segments I–IV = 0.40, 0.80, 1.00, 1.70. Labrum short; rostrum long, stout ( Fig. 1A View Fig ), length 0.95, reaching abdominal segment III.

Pronotum length 0.20, width 0.45, anterior margin weakly concave in posterior direction, lateral margins weakly divergent posteriorly, posterior margin weakly curved in posterior direction. Wing pads small, micropterous, transversely ovate.

Legs elongate, femora stout, tibiae and tarsi slender; middle and hind femora with 5 and 2 ventrolateral trichobothria respectively; lengths of leg segments as follows: fore leg femur/tibia/tarsal I/tarsal II = 0.80, 0.90. 0.10, 0.30; middle leg femur/tibia/tarsal I/tarsal II = 0.70, 0.80. 0.10, 0.30; hind leg femur/tibia/tarsal I/tarsal II = 1.00, 1.05. 0.20, 0.40.

Abdomen with all tergites exposed, lateral margins bowed outward.

Genitalia with parameres asymmetrical, blunt; left almost straight ( Fig. 3A View Fig ), right strongly hooked ( Fig. 3B View Fig ); aedeagus as in Fig. 3C View Fig .

Micropterous female: Similar to male in general structure and colouration, but slightly larger in overall size ( Fig. 1C, View Fig

D); length 1.30 mm, maximum width (across basal abdomen) 0.50 mm.

Remarks. — Mangalcoris miniatus , new genus, new species, is a very long-limbed micropterous cimicomorphan bug found under wet intertidal timber in Southeast Asian mangroves. It was initially collected in Thailand, with subsequent collections from Singapore, and there is every reason to expect a wider distribution in this specialised habitat along the intervening Southeast Asian coastline. The bright red immatures are conspicuous, but to the naked eye are likely to be dismissed as trombiculid mites, which are also common in such mangrove habitats. Adults are less conspicuous, the heavier sclerotisation concealing the red pigment, which, however, is still present. When collected by aspirator, the distinctive “ bug ” odour indicates the presence of repellant glands.

When first studied, it was suspected that this taxon might represent an undescribed family. In most of the older works, the heteropteran families are sorted on rather superficial characters of tarsal formula, presence or absence of ocelli, segmentation of the rostrum, and general habitus. Although this is adequate for most typical members of these families, it has long been known that aberrant genera exist whose placement can be difficult (McAtee & Malloch, 1924), particularly if they possess reduced wing development. One such form led China & Myers (1929) to an important reassessment on the cimicoid families, and many later workers have been critical of reliance on the traditional character suites.

This problem becomes especially difficult when dealing with species which are micropterous in both sexes, where important features of wing venation are unavailable. Fortunately recent work has emphasised the taxonomic importance of genitalic, trichobothrial, and pretarsal structures, and the characteristic scent gland apparatus, so that assigning such forms to higher taxa is no longer as speculative as it once was (Schuh & Slater, 1995). Based on an extensive character analysis, we believe that a strong case can be made for placing the following new species in the family Miridae , subfamily Cylapinae , in spite of several aberrant features subsequently discussed.

The diastome scent gland apparatus, 4-jointed rostrum, absence of trichobothria (except in Miridae ), and adult metathoracic spiracle lying ventral and anterior are among the defining apomorphies of Cimicomorpha, as defined by Leston et al. (1954). This definition was further developed by Stys & Kerzhner (1975) and summarised by Schuh (1986). The older concept of “ cimicoid families ” in the sense of China & Myers (1929) approximates this more restricted grouping though it is no longer used in its original form.

The resemblance of the tarsi in Mangalcoris to those of Plokiophila China, 1953 (see China & Myers, 1929) is quite striking, and in keys in older works the species runs to Microphysidae (from which the Plokiophilidae were subsequently separated). A more detailed appraisal of its characters however, quickly makes clear that the tarsus is the only structural resemblance between Mangalcoris and the Plokiophilidae . The male genitalia are not symmetrical, insemination is not haemocoelic, a laciniate ovipositor is present with its outer plate undivided, scent ostioles are prominent, and the basal joint of the rostrum is long with its apical joint cylindrical.

Disregarding the tarsi (and the unavailable wing structures), the full complement of available characters is otherwise typical of Miridae , in particular: 1) ocelli absent in both sexes (although this may also be linked to the uniformly apterous condition in all life stages); 2) rostrum with an elongated basal segment; 3) ovipositor lanceolate; and 4) trichobothria present on the middle and hind femora. In addition to these classic mirid characters, the following character states are present which also argue for placement in this family: 1) male with asymmetrical parameres; 2) development of a secondary phallotreme and lobate vesica (cf. Kelton, 1959); 3) female internal reproductive system with spermatheca nonfunctional and reduced to a tubular spermathecal gland; 4) lateral oviducts basally with chitinous lining; 5) ventral seminal pouch present (cf. Scudder, 1959; Davis, 1955; Matsuda, 1976); and 6) female ovipositor laciniate with discrete gonopore (cf. Scudder, 1959).

Assuming the present family placement is correct, Mangalcoris miniatus runs to the mirid subfamily Cylapinae , tribe Cylapini , in the key provided by Carvalho (1955). The two segmented tarsi and membranous vesica with sclerotised spicules are consistent with this placement in the Cylapinae . The Cylapinae are known to include several brachypterous forms, with most of these in the Fulviini . Members of the latter, however, have an elongate head of very different form to that of Mangalcoris , often possess claws with a subapical tooth, and usually have a well-developed collar on the pronotum. By contrast, the tribe Vaniini also contains a number of brachypterous species which show much greater similarities to Mangalcoris ; these include Vanniopsis howense from Lord Howe Island, and Austrovannius scutica and A. xepenehense from New Caledonia ( Cassis et al., 2003); the latter two species live in leaf litter or on fallen logs, an ecology not unlike that of Mangalcoris , although not in an intertidal setting.

In addition, the aedeagus of Mangalcoris is similar in some respects to that of Vanniopsis howense , with a large basal apparatus and a membranous distal section, and also similar in some respects to that of Kanakamiris krypton (Cassis & Monteith, 2006) , also a member of the Vaniini . This same general ground plan of the aedeagus, but with a more highly spinose distal section, is also seen in the genera Afrovannius ( Gorczyca, 1997) , Fulvius ( Gorczyca, 1998) , and Xenocylapidius ( Gorczyca, 1999) .

We have examined further cylapine material in the ZRC collection of a fungal feeding species provisionally placed near Rhinocylapus Poppius, 1909 . There are few similarities, indicating that a placement in the cylapine tribe Rhinomirini is not logical, but it is worthy of note that this is the only mirid in the ZRC collection that possesses femoral pit organs similar to those seen in Mangalcoris .

In consideration of the above, we assign Mangalcoris miniatus to the Miridae , subfamily Cylapinae , without suggesting a firm tribal placement, but with a comment that it will most likely fall into the Vaniini when a broader assessment of cylapine genera is eventually conducted, although it lacks the spatulate parempodia that are a key synapomorphy for the Vannius complex ( Cassis et al, 2003). We would further note that Cassis et al. (2003) assigned the Vaniini to the Cylapinae as incertae sedis, indicating they were not entirely comfortable with this taxonomic placement, and highlighting the uncertain phylogenetic affinities of this entire putative clade of mirid taxa.

Ecological notes. — Among the more aberrant features of Mangalcoris , apart from the micropterous condition (which is not uncommon across Miridae as a whole), is the reductional form of the tarsus and pretarsus. The general morphology of the tarsal segments is exactly as illustrated for Plokiophila and although the tarsal claws are symmetrical, the single non-central aroliar seta might be considered a step towards asymmetry. We speculate that there may be convergent evolution of character states here, possibly linked to an inverted mode of life. Plokiophilidae inhabit the webs of spiders and Embioptera, and it is possible they are adapted to hang upside down as a result. Similarly, Mangalcoris have a distinctive habit of spending all their time on the undersides of timber pieces in mangrove estuaries, and if the piece they occupy is turned upright they quickly retreat to the underside again. They do not emerge to forage on the upper side at night, nor do they move to the top side even if the timber is strongly illuminated from beneath.

Living Mangalcoris have been successfully maintained for up to a week in the lab on an inverted agar plate during attempts (so far unsuccessful) to study their feeding behaviour. The aim of these experiments was to test whether they would feed on microbiota introduced when non-nutrient plates were seeded with rotted timber from the natural habitat. Although fungi, nematodes, harpacticoids and other small organisms were available to them, no successful feeding was seen. However, during early stages of such culture they did appear to forage actively and frequently probed the substrate with their stylets. Unfortunately, by the time potential prey had multiplied significantly, the agar surface deteriorated and the bugs became entrapped. Agar is evidently an unsatisfactory substrate for these insects, and they spend a large amount of time cleaning their legs and antennae when confined to it. The general culture technique however, may still prove to be a promising one if an alternative transparent substrate, such as silica gel, is utilised, although this remains to be tested.