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Polypedilum ovahimba new species: (a) abdominal tergites, pupa; (b) posterolateral comb; (c) dorsal head and labrum, larva; (d) antenna, larva; (e) mandible, larva; (f) mentum, larva.
Source publication
A second species of Polypedilum (Diptera: Chironomidae) is inferred to tolerate desiccation in an African rock pool habitat similar to the well-known anhydrobiotic Polypedilum vanderplanki Hinton. The species, Polypedilum ovahimba sp. nov., is described and illustrated as new to science from Namibia.
Contexts in source publication
Context 1
... Tergal armament as in Figure 3a, tergite I without sternal or tergal armament. Hook row comprising 56 hooks in mostly uniserial row, extending 56-60% of width of tergite II. ...
Context 2
... non-spinose, base simple, small, circular. Abdomen. Tergal armament as in Figure 3a, tergite I without sternal or tergal armament. Hook row comprising 56 hooks in mostly uniserial row, extending 56-60% of width of tergite II. Tergites II-VI with anterior transverse band of spines connected to medial spine areas only on VI; II no median or (Fig. 3c). Fronto-clypeal apotome anteriorly broadened, with cephalic seta S3 inserted subterminally, posterior to 10 wide hyaline area. Antenna (Figs 2d,3d) with segment lengths, 45: 12: 10: 12-13: 5, AR 1.1-1.2; Lauterborn organs slender, opposite, seven to eight long; style slender 10 long; blade length 50, not extending beyond apical ...
Context 3
... to eight long; style slender 10 long; blade length 50, not extending beyond apical segment. Mandible (Figs 2e,3e): length 105-110, with dark outer tooth as long as apical, two inner teeth; inner darkened area (innermost, 'third tooth') is fused with mola, close to base of long simple seta subdentalis; mola with three to four inner spines. Labrum (Fig. 3c); SI and SII setae finely plumose, pecten epipharyngis comprises three distinctly separated scales, each with two to three blunt teeth; premandible 80, with two short teeth. Mentum (Figs 2f,3f); width 100, with rather bulbous protrud- ing median teeth, small first laterals, second laterals tall but not extending to median teeth height, ...
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Chironomid pupal exuviae were collected from coastal rock pools at Isle Royale National Park,
Michigan, from April to October in 2009 and 2010. Pools in bedrock depressions were separated into
those higher on the shore, where desiccation is likely an important disturbance, and lower on the shore,
where wave-wash from Lake Superior is likely a funda...
Citations
... According to fossil data, the heterogenous genus Polypedilum, grouping more than 520 described species inhabiting various environments in running and stagnant water, appeared around 75 Ma ) and most species do not survive desiccation for longer than a few days (Suemoto et al. 2004). However, a couple of species inhabiting temporary rock pools like P. vanderplanki can survive in dry mud for extended periods up to 6 months, but anhydrobiosis was not verified in these species, which may survive through a desiccation avoidance strategy (Cranston 2014;Cornette et al. 2022). True anhydrobiosis is expected to have been acquired exclusively in the common ancestor of P. vanderplanki and P. pembai between 65 and 33 Ma (Cornette et al. 2017). ...
The sleeping chironomid Polypedilum vanderplanki is capable of anhydrobiosis, a striking example of adaptation to extreme desiccation. Tolerance to complete desiccation in this species is associated with emergence of multiple paralogs of protective genes. One of the gene families highly expressed under anhydrobiosis and involved in this process is protein-L-isoaspartate (D-aspartate) O-methyltransferases (PIMTs). Recently, another closely related midge was discovered, Polypedilum pembai, which is able not only to tolerate desiccation but also to survive multiple desiccation–rehydration cycles. To investigate the evolution of anhydrobiosis in these species, we sequenced and assembled the genome of P. pembai and compared it with P. vanderplanki and also performed a population genomics analysis of several populations of P. vanderplanki and one population of P. pembai. We observe positive selection and radical changes in the genetic architecture of the PIMT locus between the two species, including its amplification in the P. pembai lineage. In particular, PIMT-4, the most highly expressed of these PIMTs, is present in six copies in the P. pembai; these copies differ in expression profiles, suggesting possible sub- or neofunctionalization. The nucleotide diversity of the genomic region carrying these new genes is decreased in P. pembai, but not in the orthologous region carrying the ancestral gene in P. vanderplanki, providing evidence for a selective sweep associated with postduplication adaptation in the former. Overall, our results suggest an extensive relatively recent and likely ongoing adaptation of the mechanisms of anhydrobiosis.
... In the Afrotropical region, about 90 species are recognised in this genus (Andersen et al. 2015;Ekrem et al. 2017). However, allocation of species to proper groups, which is largely based on the hypopygium characteristics (Cranston 2014), can be challenging and not all species have been allocated Saether et al. 2010;Kawai et al. 2012;Yamamoto et al. 2012). According to Ekrem et al. (2017), two afrotropical species (i.e. ...
... Another closely related anhydrobiotic species, P. pembai, has been subsequently described from Malawi (Cornette et al. 2017). Although P. vanderplanki and P. pembai are the only species exhibiting anhydrobiosis, other chironomid species, as P. ovahimba, are temporary rock pool dwellers expected to show relatively long-term desiccation tolerance (Cranston 2014). Given the habitat similarity in which P. cranstoni sp. ...
... Given the habitat similarity in which P. cranstoni sp. nov., P. ovahimba (Cranston 2014) and the two known anhydrobiotic chironomids are found, it is hypothesised that this new species should also exhibit desiccation tolerance. It is interesting to note that among chironomid species inhabiting ephemeral rock pools in Africa, species belonging to genus Chironomus, such as C. imicola and C. pulcher adopted the strategy to escape from the rock pools during the dry season and to recolonize after the first rains (Mc Lachlan 1988). ...
One newly described species of Chironomidae, Polypedilum (Pentapedilum) cranstoni sp. nov., was discovered in ephemeral rock pools from the Maloti-Drakensberg mountains in South Africa. Desiccation-resistant larvae were obtained from bottom sediments of rock pools that had been dry for the previous several months. After rehydration, ex situ adults emerged and were collected. The morphology and diagnostic characters of the new species (male and female adults) are described here together with an analysis based on their COI gene sequence.
... The climate and weather of southern Africa have a major effect on local still-water insects Bird et al. 2019). The lentic insects are well adapted to life in these dynamic habitats, and often have short lifespans, diapause during certain life stages, and have high dispersal ability (Peters 1972;Williams 2006;Cranston 2014;Bird et al. 2019). Here we highlight endemism and some adaptations among the major lentic insect groups. ...
... In the case of flies, species from the genus Polypedilum (Chironomidae), one of which occurs in Namibia, can survive complete desiccation as larvae for over six months (Cranston 2014). However, most larval or nymphal stages of aquatic insects are intolerant of complete desiccation. ...
Artificial ponds assure continuous societal water supply, especially during droughts. Obligate aquatic and amphibiotic insects readily inhabit novel water bodies, as many possess mobility traits for opportunistic colonization. We review here the value of artificial ponds (< 2 ha) (and reservoirs; > 2 ha) for local aquatic insect diversity in mostly dry and drought-prone southern Africa. We compare these ponds to natural pools, wetlands, and stream deposition pools. The region has a highly varied topography and physiographical zones. Flat, arid areas largely support widespread insect generalists, while the mountainous orographic zones support an additional rich fauna of localized endemics. However, the many ponds (> 0.5 million) have greatly changed the local distribution patterns of surface freshwater across the region, increasing the area of occupancy for many aquatic insect species, especially dragonflies. We focus on the extent to which aquatic insect assemblages have benefitted from new ponds and reservoirs. We conclude that these novel ecosystems benefit almost all lentic aquatic insect species, while also enabling population resilience during droughts. However, while these benefits are substantial, these ponds are not a substitute for natural still waters, which are still required to maintain all indigenous lentic aquatic insect diversity.
... The climate and weather of southern Africa have a major effect on local still-water insects Bird et al. 2019). The lentic insects are well adapted to life in these dynamic habitats, and often have short lifespans, diapause during certain life stages, and have high dispersal ability (Peters 1972;Williams 2006;Cranston 2014;Bird et al. 2019). Here we highlight endemism and some adaptations among the major lentic insect groups. ...
... In the case of flies, species from the genus Polypedilum (Chironomidae), one of which occurs in Namibia, can survive complete desiccation as larvae for over six months (Cranston 2014). However, most larval or nymphal stages of aquatic insects are intolerant of complete desiccation. ...
... The larvae of Polypedilum occur mostly in shallow, eutrophic waters with some being tolerant to polluted conditions (Armitage et al. 1995;Pornichu & MacDonald 2003). The species, Polypedilum ovahimba Cranston, 2014 andP. vanderplankii Hinton, 1951 are known to suspend their metabolism like tardigrades when exposed to unfavourable conditions (Cranston 2014). ...
... The species, Polypedilum ovahimba Cranston, 2014 andP. vanderplankii Hinton, 1951 are known to suspend their metabolism like tardigrades when exposed to unfavourable conditions (Cranston 2014). The phenomenon of parthenogenesis is prevalent in some population of P. parthenogeneticum Donato & Paggi, 2008(Donato et al. 2019. ...
Imagines and pupae of new species Polypedilum (Pentapedilum) retusum are described from India. Three species, P. (Polypedilum) tamanigrum Sasa, 1983, P. (Pentapedilum) anale (Freeman, 1954), and P. (Tripodura) conghuaense Zhang, Song, Qi and Wang, 2016 with pupa are recorded firstly in the subcontinent. Hypopygia of P. (P.) ascium Chaudhuri, Guha and Das Gupta, 1981, P. (T.) conghuaense, P. (T.) lineatum Chaudhuri, Guha and Das Gupta, 1981 and
P. (P.) nudiceps Chaudhuri, Guha and Das Gupta, 1981 are redescribed. Polypedilum (P.) exterflexum Hazra, Sanyal and Brahma, 2015, P. clavipennae Hazra, Sanyal and Brahma, 2015 and P. aduncum Konar and Hazra, 2017 are proposed here to transfer to the genus Stictochironomus Kieffer, 1919. Polypedilum (P.) insolitum Chaudhuri, Guha and Das Gupta, 1981is here stated as junior synonym of Zavreliella marmorata (Wulp, 1859). In addition, some biogeographic and taxonomic remarks including DNA barcoding for selected species are given. Cladistic analysis of the Oriental species of Polypedilum
Kieffer is made to hypothesise their possible relationship. A new dichotomous key of the Oriental species of Polypedilum is presented here.
... Ongoing descriptions of new chironomid species (e.g. Cornette et al., 2017;Cranston, 2014;Drayson et al., 2015) indicate a global biodiversity that is yet to be fully comprehended, particularly in the southern hemisphere (Nicacio and Juen, 2015). Chironomids often dominate natural aquatic ecosystems by abundance and biomass (Serra et al., 2016). ...
Chironomids are a formidable indicator taxon, as they are globally ubiquitous, can tolerate a wide range of environmental conditions, and can occur in high numbers in anthropogenically impaired environments where other indicator taxa are not encountered. Biomonitoring is frequently performed through analyzing species composition, abundance and morphology. However, these traditional approaches may be problematic, since indicator taxon morphology is often cryptic, and inadequately assigned species complexes may lead to generalized ecological tolerances. We argue that the use of chironomids in freshwater biomonitoring could be much improved if physiological responses to a given pollutant were measured in conjunction with precisely determined species, aided by molecular approaches such as is already done for some well known mesophilic and extremophile species in certain regions of the world. We explore molecular biological approaches that may prove useful for this purpose.
... 102°C and can survive through a wetting/ drying cycle at least ten times. An additional species of 'sleeping chironomid', P. ovahimba Cranston, 2014, has been recently described from rock pools of the Waterberg Plateau, Namibia (Cranston, 2014). ...
Temporary lentic wetlands are becoming increasingly recognised for their collective role in contributing to biodiversity at the landscape scale. In southern Africa, a region with a high density of such wetlands, information characterising the fauna of these systems is disparate and often obscurely published. Here we provide a collation and synthesis of published research on the aquatic invertebrate fauna inhabiting temporary lentic wetlands of the region. We expose the poor taxonomic knowledge of most groups, which makes it difficult to comment on patterns of richness and endemism. Only a few groups (e.g. large branchiopods, ostracods, copepods and cladocerans) appear to reach higher richness and/or endemicity in temporary wetlands compared to their permanent wetland counterparts. IUCN Red List information is lacking for most taxa, thus making it difficult to comment on the conservation status of much of the invertebrate fauna. However, except for a few specialist groups, many of the taxa inhabiting these environments appear to be habitat generalists that opportunistically exploit these waterbodies and this is hypothesised as one of the reasons why endemism appears to be low for most taxa. Given that taxonomy underpins ecology, the urgent need for more foundational taxonomic work on these systems becomes glaringly apparent.
... Immatures of Polypedilum can occur in both standing and flowing waters, even in those at high latitude and altitude (Zhang, Song, Qi, & Wang, 2016). Moreover, three Polypedilum species, including the famous sleeping midge Polypedilum vanderplanki Hinton, are known for their capability to undergo anhydrobiosis and tolerance to complete dehydration (Cornette et al., 2017;Cranston, 2014;Hinton, 1960). Polypedilum may also be among the most abundant invertebrates in eutrophic ponds, reaching densities of up to 1,200 larvae per square metre (Int Panis, Bervoets, & Verheyen, 1995). ...
Polypedilum Kieffer (Diptera: Chironomidae), with 520 currently known species worldwide, can be extremely difficult to identify species level based on the morphology. We used 3,670 cytochrome c oxidase subunit I (COI) barcodes to explore the efficiency of the COI barcodes to differentiate between species in a superdiverse aquatic insect genus. The Barcode of Life Data System (BOLD) presented 286 BIN clusters in Polypedilum, representing 163 morphospecies, of which 93 were contributed from our laboratory. Molecular operational taxonomic units (OTUs) ranged from 158 to 345, based on Automatic Barcode Gap Discovery (ABGD), the Barcode Index Number (BIN), Bayesian Poisson tree processes (bPTP), generalized mixed Yule coalescent (GMYC), jMOTU, multi‐rate Poisson tree processes (mPTP), neighbor‐joining (NJ) tree and prethreshold clustering. In comparison, GMYC, bPTP, mPTP and BIN suggested more species than warranted by morphology, while ABGD, jMOTU, NJ, prethreshold clustering and ABGD yielded a conservative number of species when setting higher thresholds. Nine species complexes with deep intraspecific divergences indicated 18 potentially cryptic species, which require further taxonomic research including complete life histories and nuclear genetic data to be resolved. The discrimination of Polypedilum species by DNA barcodes proved to be successful in 94.4% of all studied morphological species.
... Recently, a new chironomid species, Polypedilum ovahimba, was described from Namibia (Cranston, 2014). Polypedilum ovahimba larvae were found in temporary rock pools similar to the harsh habitat of P. vanderplanki and this species was thus suggested to be anhydrobiotic. ...
The sleeping chironomid (Polypedilum vanderplanki Hinton) lives on temporary rock pools in the semi-arid tropical regions of Africa. Its larvae are able to survive the dry season in a completely desiccated ametabolic state known as anhydrobiosis. So far, P. vanderplanki was the only species among all insects showing demonstrated anhydrobiotic ability. Here, we show that a new related species originating from Malawi, Polypedilum pembai sp.n., is also anhydrobiotic and that its desiccation tolerance mechanism is probably similar to what is observed in P. vanderplanki. The new species, P. pembai sp.n., is described with special attention to the common and different morphological features, compared with P. vanderplanki. Phylogenetic analysis showed that both species are closely related, suggesting that anhydrobiosis evolved only once in their common ancestor about 49 Ma somewhere in Africa, before the divergence of two species, one in the sub-Saharan area and another in southeastern Africa.
... However, chironomids which can aestivate and are tolerant to the body water loss, e.g. Polypedilum vanderplanki Hinton, 1951, are much more resistant than the above-mentioned species (Watanabe et al., 2002;Frouz et al., 2003;Cranston, 2014). Hence, S. sticticus appears as a relatively resistant chironomid species, well adapted to periodically emersed habitats and capable of surviving 5-6 days of the substratum emersion in laboratory conditions. ...
Organisms inhabiting shallow near-shore waters experience emersion during water-level fluctuations, which are increasing in frequency and magnitude due to climate change and anthropogenic activities. We experimentally investigated the survival and behaviour of two common shallow-water and psammophilous invertebrates, the chironomid Stictochironomus sticticus and the oligochaete Potamothrix moldaviensis, during sandy substratum drying. We examined horizontal migrations following a decreasing water level in inclined tanks and vertical migrations into substratum. In drying tanks, the substrate was initially submerged and then water was gradually evaporated to expose the surface sediments. In control tanks, the substratum remained submerged. We hypothesised that the organisms would tolerate drying (surviving at least while the substrate remained moist) and/or migrate vertically and/or horizontally under drying conditions. Chironomids were tolerant of drying, with 90% mortality occurring at the sediment water content (LWC90) of 0.3% (dry sand). They exhibited neither horizontal nor vertical migrations in response to drying. Oligochaetes were far less resistant to drying (LWC90 = 13.9%, corresponding to humid sand) and did not exhibit any behavioural adaptations. Thus, our hypothesis was supported with regard to the resistance to drying of chironomids, but not that of oligochaetes. Contrary to our hypothesis, neither species exhibited behavioural adaptations to drying.
