Macrholaspis Oudemans, 1931

Emberson, Rowan M., 2010, A reappraisal of some basal lineages of the family Macrochelidae, with the description of a new genus (Acarina: Mesostigmata), Zootaxa 2501, pp. 37-53 : 48-49

publication ID	https://doi.org/ 10.5281/zenodo.195835
DOI	https://doi.org/10.5281/zenodo.6212254
persistent identifier	https://treatment.plazi.org/id/03997670-FFB0-E66C-8ECB-FC7A72DF691A
treatment provided by	Plazi
scientific name	Macrholaspis Oudemans, 1931
status

Treatment

Macrholaspis Oudemans, 1931: 272 . Type species: Gamasus opacus Koch, 1839 , by original designation. Macrocheles opacus species group.— Johnston, 1970: 148.

Medium sized (female dorsal shield usually 600–1100 μm in length), litter-dwelling Macrochelini; dorsal shield with 28 pairs of setae, plus 1–4 unpaired or paired setae; setae long, tapered and usually entirely pilose; j1 laterally expanded; dorsal shield tapered posteriorly, lateral and posterior margins dentate, crenulate or smooth; ventri-anal shield rounded or subcircular, with 1–3 pairs of pre-anal setae; three pairs of postepigynal platelets free in membranous cuticle; lateral processes of epistome reduced; cheliceral dorsal seta pectinate laterodistally.

The dorsal shield has a basic complement of 28 pairs of setae plus 1–4 additional unpaired or paired setae; setae J3 are always present and a single seta, or a pair of setae, or 3–4 unpaired setae are present between setae j6 and J3. Setae j1 are short and laterally expanded; the other setae are long, tapered and pilose along their entire length (except for M. evansi Balogh , in which setae j6, z6, J3 and a pair between j6 and J3 are aciculate). Setae z1 and J5 are often shorter than the other setae. The dorsal shield is tapered from the shoulders and does not cover the entire dorsum. It may be ornamented with microspicules or have reticulated surface sculpture. The lateral and posterior margins of the dorsal shield are often finely dentate or crenulate. The ventral sclerotisation is reduced and the setae are aciculate or pilose. The sternal shield is punctatereticulate without strong lineal patterns. The epigynal shield is reduced and rounded posteriorly, with the pores free in the membrane. The ventri-anal shield is more or less reduced, usually rounded or subcircular, with 1–3 pairs of pre-anal setae and a cribum with strong para-anal extensions. There are three pairs of sclerotised post-epigynal platelets free in membranous cuticle. The lateral processes of the epistome are usually reduced to narrow spikes, either attached to the median process or free ( Fig. 17 View FIGURES 12 – 17. 12 – 15 ), but they are absent in M. carpathicus Mašán. The median process is bifurcate and usually dissected distally. The fixed chela has an offset subterminal tooth and a median tooth, and the female movable chela has two central teeth. The cheliceral dorsal seta is pectinate laterodistally. The legs are strongly rugose, with setation normal for the family. The setae are mainly pilose or occasionally blade-shaped, except on coxa and tarsus I where they are aciculate. The visible spermathecal structures include elongate tubuli and well developed rami; the sacculus is indistinct.

Males, where known ( M. beieri (Johnston) and M. reductus (Petrova)) , have separate sternogynal and ventri-anal shields. The male movable chela is unidentate with a short, strongly tapered, posteriodorsally directed spermatodactyl. Femur II has a ventral spur.

Notes. Macrholaspis is distinguished from Macrocheles by the reduced ventral sclerotisation and by the presence of three pairs of sclerotised post-epigynal platelets in the membrane between the epigynal and ventri-anal shields, a feature shared with Nothrholaspis and Geotrupacarus . Macrholaspis is further distinguished from other genera by the distinctive shape of the epistome, the fully pilose dorsal setae, the laterally expanded setae j1, the litter dwelling habit, and the rarity of males.

Hyatt & Emberson (1988) saw no males among 116 adults of the three species occurring in the British Isles, and Mašán (2003) did not report any males among nearly 200 specimens of six species from Slovakia. Johnston (1970) stated that M. beieri Johnston was the only species of the genus (species group) for which males were known. This, however, is not strictly correct; Petrova (1966), in describing M. reductus , clearly indicated and illustrated the male of the species, but compared it to species of Nothrholaspis rather than Macrholaspis .

Macrholaspis is closely related to Nothrholaspis , and a case could be made for regarding it as a subgenus of the latter. However, the epistomal structure of Macrholaspis is quite different from that of Nothrholaspis , as are the fully pilose dorsal setae and the laterally expanded setae j1. The two genera share the presence of three pairs of sclerotised post-epigynal platelets with Geotrupacarus , a feature otherwise seen only rarely in the family. These three genera also have para-anal extensions of the cribrum, an apparently pleisiomorphic character that occurs widely in free-living, early derivative lines of the Macrochelidae (including Geholaspini), but is absent in most species of Macrocheles . The males of these three genera also have separate sternogynal and ventri-anal shields and major spurs on the legs are limited to femora II. Males of more derived species of Macrocheles often have holoventral shields and may have additional spurs on legs II and IV.

Macrholaspis is a Palaearctic genus with species distributed from Britain and Ireland to Japan ( Hyatt & Emberson 1988, Ishikawa, 1969), but appears to be most diverse in Central Europe ( Balogh 1958, Johnston 1970, Mašán 2003).

As pointed out by Mašán (2003), Macrocheles punctatissimus Berlese is not a species of Macrholaspis , although it was tentatively included in the opacus species group by Hyatt & Emberson (1988). It lacks the definitive characters of the genus, particularly the reduced ventral sclerotisation, the free post-epigynal platelets, the reduced lateral processes of the epistome, and the pectinate cheliceral dorsal seta. Macrocheles analis Hyatt & Emberson , also placed in the opacus species group by Hyatt & Emberson (1988), has been transferred to Reductholaspis , a distinctive new genus apparently more closely related to Longicheles than to Macrholaspis (see above).

Kingdom	Animalia
Phylum	Arthropoda
Class	Arachnida
Order	Mesostigmata
Family	Macrochelidae