Mypongia brevipes Southcott 1961
Creators: name: Seeman, Owen D.
name: Beard, Jennifer J.
name: Fan, Qing-Hai
name: Otto, Jürgen C.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Trombidiformes
Erythraeidae
Mypongia
Mypongia brevipes

description: Mypongia brevipes Southcott, 1961
Figures 1–6
Diagnosis. Larva. Prodorsal sclerite reduced to an irregular region of smooth soft cuticle around crista metopica; prodorsum with 4 pairs of setae. Dorsum with 18 pairs of setae, mildly hypertrichous C row (six pairs) and D row (four pairs). Coxa I with two pairs of setae; coxa II lacking setae. Gnathosoma lacking proximal setae bs. Palp slender, femur and tibia each at least twice as long as wide, all palp setae smooth and unspecialised; paradont absent. Leg setation reduced, especially genua and tibiae II–III; setal counts, trochanter to tarsus: leg I 2-3/5-8+σ-10+2ϕ+κ–16+duplex+ω+ε; leg II 2-3/4-5+σ+κ-5+2ϕ-13+duplex+ω; leg III 2-3/4–5+σ-5+ϕ-14. Leg setae smooth or sparsely barbed.
Material examined. 4 larvae, as follows. New Zealand: 1 larva, ex kiwifruit, 28 Sep 2000 (QMB; Q19775). 1 larva, ex kiwifruit, 3 Jun 2015 (N162334), drawn specimen. 1 larva, ex kiwifruit, 14 Nov 2020 (BISS: 399629, Q180666, 132763QA) [fragments of specimen—idiosoma and one leg, matched but not measured]. South Australia: 1 larva, Belair, 30 May 1990, R.V. Southcott, soil and litter under Euc. camaldulensis. Tx 305, By B. t. on 7 Jun 1990 (SAM J24237) [poor mount, measured where possible].
Other material examined. South Africa: 1 larva, Potchefstroom, ex moist litter and grass, 28 Apr 1982, D.E. Johnston [SAM J24239] (identified as an undescribed species of Mypongia).
Description (n=3 measured).
Metric data in Table 2.
Dorsum (Figs 1, 3A). Scutum reduced to a lightly sclerotised region poorly defined by limits of prodorsal striation, lacking setae. Crista well-defined, anteriorly and posteriorly capturing trichobothria ASens and PSens, respectively. ASens and PSens slender with few tiny barbs. Prodorsum with 4 pairs of setae, AL setae shortest, scapular (Sc) setae longest; ML, PL intermediate in length; all prodorsal setae slender, with few barbs; epl microphalliform, typical for Trombidiformes. Opisthodorsum with 18 pairs of setae, becoming slightly thicker and longer posteriorly; mid C-row setae irregular in position, other opisthosomal setae in pairs forming rows.
Venter (Fig. 2). Striae between coxae I–II longitudinal; region between coxae II–III with six pairs of setae (excluding 3a), medial striae alternating between regions of transverse and longitudinal; opisthoventer with nine pairs of setae (including ps1-2), striae transverse (arching medially). All setae fine; setae 1a, 1b, 1c, 3b smooth; all other setae with few barbs. Apodemes I–III with narrow anterior margins, posterior margins poorly defined; coxae I-II adjacent, lacking setae in between.
Abbreviations from Southcott (1961, 1992): IL, idiosoma length; IW, idiosoma width; ISD, distance ASens-PSens; AW, distance setae AL-AL; MW, distance setae ML-ML; PW, distance setae PL-PL; AP, distance AL-PL; AL, ML, PL setal lengths; L, scutum length; W, scutum width; SBa distance between anterior sensilli bases; SBp, distance between posterior sensilli bases; ASens, anterior sensillus length; PSens, posterior sensilli length; Oc, eye diameter; CDS, length of central dorsal setae; PDS, length of posterior dorsal setae.
Gnathosoma (Fig. 3B, C; 4A, B). Anterior ventral gnathosoma with four pairs of setae, cs fine, 14–17, as1- 2 small (5–6), as3 slightly longer (7–9) and thicker. Dorsally with small rod-like supra palp-coxal seta ep. Palp elongate, almost linear (i.e. not conspicuously elbowed); palp femur 45–46 long, 20–22 wide; genu 30–31 long, 17– 20 wide; palp tibia with simple odontus, lacking paradont; palp tarsus with seta ul′′ longest, eupathidion ξ slightly shorter, solenidion ω thin. Setal counts femur-tarsus: 2-3-3+claw-5+ω+ξ. Chelicerae hook-like, lacking teeth.
Legs (Figs 4 C–E, 5–6). Leg segmentation formula 7-7-7. All legs shorter than body, legs I and III longest. Leg setation reduced in number, all setae fine and smooth or with few barbs. Genu I with one solenidion σ, lacking microseta κ; genu II with one solenidion σ, with minute microseta κ; genu III with one solenidion σ. Tibia I with two solenidia ϕ and microseta κ in line, decreasing in size distally; tibia II with two solenidia ϕ well-separated from each other, lacking microseta κ; tibia III with one solenidion ϕ. Tarsus I with famulus ε distant from dorsal duplex setae formed by long eupathidion tcξ′ and small fine companion seta z; proral seta p′ fine and densely barbed (perhaps better interpreted as u′′, with p′ absent), eupathidial pξ′′ smooth, long, thin; tarsus II with duplex setae (tcξ′ + z) and long thin proral eupathidion pξ′′; tarsus III with tc′ barbed tactile seta, lacking companion seta z. Claws and empodia claw-like, smooth. Setal formulae, trochanters to tarsi: leg I 2-3/5-8+σ-10+2ϕ+κ-16+duplex+ω+ε; leg II 2-3/4-5+σ+κ-5+2ϕ-13+duplex+ω; leg III 2-3/4-5+σ-5+ϕ-14. Leg setae smooth or sparsely barbed.
Remarks. Southcott (1961) described M. brevipes from a single larva collected from vegetation at Myponga, an elevated locality close to the coastline at the southern end of the Mt Lofty Ranges, South Australia. The holotype was unavailable for study because it is missing from the SAM, but the material from New Zealand matches Southcott (1961) closely (Table 2). In addition to the newly collected material from New Zealand, the South Australian Museum held two additional larval Mypongia specimens. The specimen from Belair, South Australia, is partially spoiled, overly flattened and crumpled. The measurements also match the Southcott description well (PSens is somewhat smaller; Table 2), but there may be an intercoxal seta (apparently asymmetrically expressed) between coxae I-II and two setae on coxae II (asymmetrically expressed). The setae on coxae II could be illusions caused by a fold of soft seta-bearing cuticle. The larval specimen from South Africa is an undescribed species that was collected with an adult Abrolophus species close to A. ripicola (Tables 1, 2). In addition to the measurements, particularly the PSens being much longer than ASens (Table 2), the crista is punctate and similar to that of nymphal and adult A. ripicola.
Mypongia is a highly distinctive larva. The leg setation is greatly reduced, with the most reductions being on genu II-III and tibia II-III (only 5 tactile setae). As far as we are aware, other larvae of Erythraeidae have 7–9 genual setae and 10–13 tibial setae on leg II. Setal counts are usually similar on leg III, although some exceptions exist (e.g. Monteustium marezensis Haitlinger & Sundic 2015 has 11+ϕ+k on tibia II and 8+ϕ on tibia III). In Southcott’s (1961) classification, the larva of M. brevipes belongs to the Balaustiinae due to its crista and absence of a prodorsal sclerite.
description: Published as part of Seeman, Owen D., Beard, Jennifer J., Fan, Qing-Hai & Otto, Jürgen C., 2024, Abrolophus from Australasia, and the mysterious Mypongia (Trombidiformes: Parasitengona: Erythraeidae), pp. 151-189 in Zootaxa 5519 (2) on pages 152-160, DOI: 10.11646/zootaxa.5519.2.1, http://zenodo.org/record/13915687