Oriental Region Research Articles

Revision of the plant bug genus Diognetus, with descriptions of thirteen new species from the Oriental and Eastern Palearctic Regions (Hemiptera: Heteroptera: Miridae)

The mirine plant bug genus Diognetus Distant, 1904 (Hemiptera: Heteroptera: Miridae: Mirinae: Mirini) is revised. Eighteen Oriental and Eastern Palearctic species are properly assigned to the genus. Diplotrichiella Poppius, 1915, syn. nov. and Yamatolygus Yasunaga, 1994, syn. nov. are synonymized with Diognetus; accordingly the following two new combinations, one substitute name and one new synonymy are proposed: Diognetus flavigenis (Horváth, 1905) comb. nov. and D. insulanus (Yasunaga, 1994) comb. nov. (transferred from Yamatolygus); D. yamato Yasunaga nom. nov. for Yamatolygus pilosus Yasunaga, 1994, junior secondary homonym of D. pilosus (Poppius, 1914); and Diplotrichiella rufescens Poppius, 1914, syn. nov. = Diognetus intonsus Distant, 1904 (valid name). Thirteen species are described as new: Diognetus bagmaticus sp. nov. (from Nepal), D. cheimon sp. nov. (Japan), D. dhampus sp. nov. (Nepal), D. duwalorum sp. nov. (Nepal), D. giganteus sp. nov. (Malaysia), D. gotohi sp. nov. (Malaysia), D. laureus sp. nov. (Japan), D. magnificus sp. nov. (Indonesia), D. minusculus sp. nov. (Malaysia), D. puspae sp. nov. (Nepal), D. schuhorum sp. nov. (Indonesia), D. styrax sp. nov. (Taiwan) and D. vernus sp. nov. (Japan). The generic characters are reassessed and discussed, on the basis of detailed observation of external structures using scanning electron microscopy as well as male and female genitalia.

A New Species of <i>Pseudotocepheus</i> Balogh 1960 (Acari, Oribatida, Otocepheidae) from <i>Dipterocarpus alatus</i> in Vietnam, with a Key to the Known Species of the Genus from the Oriental Region

A new mite species of the genus Pseudotocepheus (Oribatida, Otocepheidae), collected from the bark of Dipterocarpus alatus in the Cat Tien National Park, southern Vietnam, is described. Pseudotocepheus cattienensis sp. n. differs from P. setiger in a smaller body size, a fusiform bothridial seta, two pairs of medial prodorsal condyles, poorly developed medial notogastral condyles, the lamellar seta being distinctly removed from the bothridium, a tuberculate posterior part of the notogaster, and a setiform seta d on leg femora I and II. In addition, an identification key to the species of Pseudotocepheus from the Oriental Region is given.

Where are they from and where are they going? Detecting areas of endemism, distribution patterns and conservation status of the order Spirostreptida in Brazil (Diplopoda, Juliformia)

Millipedes are well-known for their limited dispersal abilities with species restricted to mountains, islands, and patches of forest being important models for formulating and testing biogeographic hypotheses. The order Spirostreptida is composed of nearly 1300 species distributed across the Afrotropical, Oriental, and Neotropical regions. The order is divided into the suborders Cambalidea and Spirostreptidea with the families Pseudonannolenidae (Cambalidea) and Spirostreptidae (Spirostreptidea) occurring in Brazil. To date, there have been no studies on the biogeography of Neotropical Spirostreptida. We employed a multi-approach analysis with Parsimony Analysis of Endemicity, Endemicity Analysis, and Infomap, to detect areas of endemism and patterns of distribution of the order in Brazil. Six areas of endemism are proposed for the 133 Brazilian species: Northern Serra Geral, Southeastern mountain ranges, Cerrado and Atlantic Forest zone, Eastern Cerrado and Serra do Espinhaço, Pantanal, and Southern Amazon and Cerrado zone. Most endemic areas fall within the Atlantic Forest, which has been previously shown to be an important area of endemism for many invertebrate taxa. The richest biomes are the Atlantic Forest with 75 species and the Cerrado with 55 species, while the least rich biomes are the Caatinga with six species and the Pampa with three species. Although the southeastern region of Brazil has the highest species richness, it also has the highest concentration of threatened species. Based on International Union for Conservation of Nature (IUCN) criteria, most Brazilian Spirostreptida are either endangered or critically endangered, with the highest concentration of endangered taxa occurring in the Atlantic Forest biome.

First report of the fairyfly Schizophragma mitai Triapitsyn (Hymenoptera: Mymaridae) from India with notes on S. indica Rehmat & Anis

The fairyfly species Schizophragma mitai Triapitsyn is reported for the first time from the Oriental region. Since the extension of range from the Palaearctic region to the Oriental region, the species is redescribed based on the Indian material. A detailed note on S. indica Rehmat & Anis is provided with an observed variation. The illustrations and updated distribution map of both species are also included.

Wasp-mimicking soldier flies of the Australian Region: revision of Ampsalis Walker, Elissoma White and Lagenosoma Brauer (Stratiomyidae: Clitellariinae)

The genera Lagenosoma Brauer, 1882 (= Peratomastix Enderlein, 1914 syn. n.), Elissoma White, 1916 (= Pycnothorax Kertész, 1923 syn. n.) and Ampsalis Walker, 1859 (Stratiomyidae: Clitellariinae) are revised. Three species of Elissoma are redescribed (i.e., E. australis (Kertész, 1923) comb. n., E. brunnea, Hardy, 1933, and E. lauta White, 1916) and seven species are described as new. Similarly, three species of Lagenosoma are redescribed (i.e., L. dispar Brauer, 1882 (= Peratomastix australis Enderlein, 1914 syn. n.), L. pictum Brauer, 1882 and L. propinquum Brauer, 1882) and seven species are described as new. Ampsalis sensu lato is represented by two species in Indonesia and two species in Madagascar; here the Indonesian species are circumscribed as Ampsalis sensu stricto (i.e., A. geniata Walker, 1859 and A. iterabilis (Walker, 1859)) with two additional species described from northern Australia. Eudmeta Wiedemann, 1830 is diagnosed and a new synonymy identified (i.e., E. marginata (Fabricius, 1805) (= E. coerulemaculata Yang, Wei et Yang, 2010 syn. n.)). A revised key to Clitellariinae genera of the Oriental and Australian regions is presented, as well as keys to species of Ampsalis, Elissoma, Eudmeta and Lagenosoma.

Metabolic and microbial changes in light-vented bulbul during recent northward range expansion.

Endotherms recently expanding to cold environments generally exhibit strong physiological acclimation to sustain high body temperature. During this process, gut microbes likely play a considerable role in host physiological functions, including digestion and thermogenesis. The light-vented bulbul Pycnonotus sinensis represents one such species. It used to be restricted to the Oriental realm but expanded its distribution range north to the Palearctic areas during the past few decades. Here, we explored the seasonal dynamics of the resting metabolic rate (RMR) and microbiota for local and newly colonized populations of the species. Our results showed that the mass-adjusted RMR and body mass were positively correlated with latitude variations in both seasons. Consistently, the gut microbiota showed a corresponding variation to the northern cold environments. In the two northern populations, the alpha diversity decreased compared with those of the two southern populations. Significant differences were detected in dominant phyla, such as Firmicutes, Bacteroidetes, Proteobacteria, and Desulfobacterota in both seasons. The core microbiota showed geographic differences in the winter, including the elevated relative abundance of 5 species in northern populations. Finally, to explore the link between microbial communities and host metabolic thermogenesis, we conducted a correlation analysis between microbiota and mass-adjusted RMR. We found that more genera were significantly correlated with mass-adjusted RMR in the wintering season compared to the breeding season (71 vs. 23). These results suggest that microbiota of the lighted-vented bulbul linked with thermogenesis in diversity and abundance under northward expansion.

A new and some interesting species of ptyctimous mites (Acari, Oribatida) from different countries of the all worldly zoogeographical regions

In the paper, we presented ptyctimous mites collected from Nearctic (Canada, USA), Neotropical (Dominicana), Palaearctic (Scotland, Italy, Russia, Nepal, Egypt), Afrotropical (Ethiopia, Gabon, Congo, Mozambique, Madagascar, Réunion), South Africa, Oriental (Maldives, Vietnam, Malaysia, Indonesia, China) and Australasian (Papua New Guinea, Australia, New Zealand) regions. Information of Mesoplophora (Parplophora) flavida Niedbała, 1985 and M. (P.) polita Niedbała, 1985 phoretic on different insects (Coleoptera: Passalidae) are presented. A new species Atropacarus (Hoplophorella) additus Niedbała sp. nov., is described from Madagascar. Supplementary descriptions and some remarks of ten species from six genera are given (including two paratypes of previously synonymous species). Information on the distribution and location of 85 species of 18 genera is also presented. Fifty-three species were found for the first time in the zoogeographical region or given country.

A new species of Pseudovelia Hoberlandt, 1950 (Hemiptera: Heteroptera: Veliidae) from Honshu, Japan

The genus Pseudovelia occurs at the margins of freshwater bodies and is widely distributed in the Palearctic and Oriental regions. It is represented by 29 species in the East and Southeast Asian mainland, of which five are known from Japan. Described here is Pseudovelia lasiomma sp. nov. from Lake Biwa, Honshu, Japan. In addition, a key is provided to facilitate the identification of the six species of Pseudovelia now known from Japan.

Molecular phylogeny and historical biogeography of Cyclommatus stag beetles (Coleoptera: Lucanidae): Insights into their evolution and diversification in tropical and subtropical Asia

Cyclommatus stag beetles (Coleoptera, Lucanidae) are very interesting insects, because of their striking allometry (mandibles can be longer that the whole body in large males of some species) and sexual dimorphism. They mainly inhabit tropical and subtropical forests in Asia. To date, there has been no molecular phylogenetic research on how these stag beetles evolved and diversified. In this study, we constructed the first phylogenetic relationship for Cyclommatus using multi-locus datasets. Analyses showed that Cyclommatus is monophyletic, being subdivided into two well-supported clades (A and B). The clade A includes the island species from Southeast Asia, and the clade B is formed by the continental species. The divergent time estimates showed these beetles split from the outgroup around 43.10 million years ago (Mya) in the late Eocene, divided during the late Oligocene (around 24.90 Mya) and diversified further during the early and middle Miocene (around 18.19 Mya, around 15.17 Mya). RASP analysis suggested that these beetles likely originated in the Philippine archipelago, then dispersed to the other Southeast Asian archipelagoes, Indochina Peninsula, Southeast Himalayas, and Southern China. Moreover, relatively large genetic distance and stable morphological variations signified that the two clades reach the level of inter-generic differences, i.e., the current Cyclommatus should be separated in two genera: Cyclommatus Parry, 1863 including the clade A species, and Cyclommatinus Didier, 1927 covering the clade B species. In addition, the evidence we generated indicated these beetles’ diversification was promoted probably by both long-distance dispersal and colonization, supporting an “Upstream” colonization hypothesis. Our study provides insights into the classification, genetics and evolution of stag beetles in the Oriental region.

Three New Eriophyid Mite Species from China (Acari: Eriophyidae).

Eriophyid mites (Eriophyidae) are strictly phytophagous and are concentrated in Europe, Eastern Asia, Southeast Asia, Western and Eastern North America, Southern India, and New Zealand. South and southwest China are hot spots for eriophyid mite species diversity and endemism. In this study, we describe two new species, Scolotosus ehretussp. nov. on Ehretia acuminata (Boraginaceae) and Neotegonotus ulmchangussp. nov. on Ulmus changii (Ulmaceae), from south and southwest China (the Oriental Region), and one new eriophyid mite, Leipothrix ventricosissp. nov. on Hosta ventricosa (Asparagaceae), from northeast China (the Palearctic Region). All three new eriophyid mite species are distributed in the temperate region of China. We further provided mitochondrial gene (cox1, 12S rRNA) and nuclear gene (18S rRNA, 28S rRNA) sequences for three new species.

Omorgus (Omorgus) khandesh (Coleoptera: Scarabaeoidea: Trogidae), a new species from India, along with an annotated catalogue of the Oriental and Palearctic species of the subgenus Omorgus Erichson, 1847

A new species of keratin beetle from Western India, Omorgus (Omorgus) khandesh Strümpher & Kalawate, new species, is described and illustrated. The new species is morphologically most similar to O. (O.) rimulosus (Haaf, 1957). The latter is redescribed and illustrated to enable accurate recognition of both species. Based on this work the following taxonomic changes are proposed: Three species are transferred from the subgenus Afromorgus Scholtz, 1986 to the nominotypical subgenus: O. (O.) inclusus (Walker 1858), O. (O.) maissouri (Haaf, 1945a) and O. (O.) rimulosus (Haaf, 1957). Lastly, we include an annotated catalogue of the species of the nominotypical subgenus Omorgus known from the Oriental and Palaearctic regions.

Global population genetic structure and lineage differentiation of the stable fly, Stomoxys calcitrans.

The bloodsucking fly, Stomoxys calcitrans (Diptera: Muscidae), is a cosmopolitan pest that transmits potential pathogens mechanically. We conduct phylogeographic analyses of S. calcitrans to resolve its global population genetic structure for establishing baseline of molecular studies. Results from mitochondrial gene suggested that the major divergence of S. calcitrans predominantly occurred 0.32-0.47 million years ago (Mya) and the subsequent diversifications took place during 0.13-0.27 Mya. The Ethiopian region was deduced as the most likely origin of S. calcitrans and the Nearctic lineages were considered to have originated from Oriental or Palaearctic regions. Our results further revealed that each biogeographic region of S. calcitrans likely maintains its genetic specialty, and yet, those non-monophyletic relationships were possibly caused by ancestral retention, dispersal with mammals, long-distance migration, and the international livestock industries. Moreover, the three highly diverged Ethiopian lineages may be putative cryptic species that require clarification of their veterinary importance. Unravelling the genetic structure of stable fly and preventing gene flow among biogeographic regions through anthropogenic activities are thus pivotal in livestock industry administration, particularly genetic exchange among differentiated lineages that might lead to the consequence of ecological trait alterations.

Bionomics of Phlebotomine Sand Flies in Different Climates of Leishmaniasis in Fars Province, Southern Iran.

Phlebotomus and Sergentomya are distributed in the old-world regions and transmit leishmaniases through mammalian and reptile hosts. Cutaneous leishmaniasis (CL) is one of the most important diseases in Iran. Iranian sand flies belong to three Oriental, Palearctic, and Afrotropical Regions. Fars Province is located in Palearctic, but southern parts are affected Oriental region situations on phglebotomine population variety. Therefore, a comprehensive study was required on the vectors of the disease in this Province. Regarding the approved role of the environmental factors in creating the fauna and distribution of living creatures, the "de martonne climate method" was used, and the climate was noticed as an important environmental factor for the determination of vector distribution. Accordingly, 14 sampling sites were selected from 10 foci in different climates of Fars Province. 19648 sand flies were collected from the studied areas in this Province during 2016. Phlebotomus papatasi and Se. antennata were the most frequent species, which were caught from in/outdoor areas. Phlebotomus sergenti and Ph. alexandri were caught from both Palearctic and Oriental zones but were more prevalent in the cold semi-arid climate of the Palearctic zone. Moreover, they were not caught from the hot desert and summer Mediterranean climates of the Oriental zone. It seems that Ph. papatasi as the main vector of CL could be well distributed in different climates in Fars. Moreover, some species like Ph. sergenti preferred especial climates in the Palearctic zone. Therefore, these data could be helpful to control leishmaniases more efficiently.

Phylogenetic Position of Haemaphysalis kashmirensis and Haemaphysalis cornupunctata, with Notes on Rickettsia spp.

Despite high diversity in the Oriental region, ticks of the genus Haemaphysalis have been neglected regarding their genetic data and vector potential. This study aimed to genetically characterize three species of the genus Haemaphysalis: Haemaphysalis cornupunctata, Haemaphysalis kashmirensis, and Haemaphysalis montgomeryi infesting goats and sheep, and Rickettsia spp. associated with these tick species in the Hindu Kush Himalayan range of Pakistan. Altogether, 834 ticks were collected by examining 120 hosts including goats (64/120, 53.3%) and sheep (56/120, 46.6%), in which 86 (71.6%) hosts were found to be tick-infested. The morphologically identified ticks were subjected to DNA extraction and PCR for the amplification of partial 16S rDNA and cox fragments. Rickettsia spp. associated with the collected ticks were detected through the amplification of gltA, ompA and ompB partial fragments. The 16S rDNA of H. cornupunctata and H. montgomeryi showed a maximum identity of 100% with the sequences of the same species, whereas the 16S rDNA of H. kashmirensis showed the highest identity of 93-95% with Haemaphysalis sulcata. The cox sequence of H. montgomeryi displayed 100% identity with the same species. In comparison, the cox sequences of H. cornupunctata and H. kashmirensis showed maximum identities of 87.65-89.22% with Haemaphysalis punctata and 89.34% with H. sulcata, respectively. The gltA sequence of Rickettsia sp. from H. kashmirensis showed the highest identity of 97.89% with Rickettsia conorii subsp. raoultii, while the ompA and ompB fragments from the same DNA samples revealed 100% and 98.16% identity with Rickettsia sp. and "Candidatus Rickettsia longicornii", respectively. Another gltA sequence amplified from H. montgomeryi ticks showed 100% identity with Rickettsia hoogstraalii, while the attempts to amplify ompA and ompB for R. hoogstraalii were unsuccessful. In the phylogenetic tree, the 16S rDNA of H. cornupunctata clustered with the corresponding species while its cox clustered with H. punctata. Both 16S rDNA and cox sequences of H. kashmirensis clustered with H. sulcata. The gltA sequence of Rickettsia sp. was clustered individually in the spotted fever (SF) group of Rickettsia, while the gltA sequence of R. hoogstraalii was clustered with the same species in the transition group of Rickettsia. In the SF group, the rickettsial ompA and ompB sequence clustered with undetermined Rickettsia sp. and "Candidatus Rickettsia longicornii", respectively. This is the earliest study regarding the genetic characterization of H. kashmirensis. This study indicated that ticks belong to the genus Haemaphysalis have the potential of harboring and/or transmitting Rickettsia spp. in the region.

Review of the tribe Smicromyrmini Bischoff, 1920 (Hymenoptera: Mutillidae)

Twenty-six genera and five subgenera of the tribe Smicromyrmini are reviewed. The tribe (528 valid species) is Afrotropical (15 genera /126 species), Palaearctic (13/213) and Oriental (14/204) in distribution. The females are known for 80%, and males for 87%, of the 26 genera and five subgenera. The hitherto unknown female of Rasnitsynitilla Lelej in Lelej & van Harten, 2006 is described. New combinations are proposed for Rasnitsynitilla bartolozzii (Lo Cascio et Grita, 2014), comb. nov. (from the genus Smicromyrme Thomson, 1870) and Skorikovia sanguinicollis (Klug, 1829), comb. nov. (from the genus Ephutomma Ashmead, 1899). The genus Indratilla Lelej, 1993 is newly recorded from India and the subgenus Eremotilla Lelej, 1985 from the Oriental Region. Keys to females and males of these genera and subgenera of Smicromyrmini are provided. Habitus photos of males and/or females are provided for each genus and subgenus.

Distribution patterns of established alien land snail species in the Western Palaearctic Region

Established alien land snail species that were introduced into the Western Palaearctic Region from other regions and their spread in the Western Palaearctic are reviewed. Thirteen of the 22 species came from North America, three from Sub-Saharan Africa, two from the Australian region, three probably from the Oriental Region and one from South America. The establishment of outdoor populations of these species was usually first seen at the western or southern rims of the Western Palearctic. Within Europe, the alien species usually spread from south to north and from west to east. The latitudinal ranges of the alien species significantly increased with increasing time since the first record of introduction to the Western Palearctic. The latitudinal mid-points of the Western Palaearctic and native ranges of the species are significantly correlated when one outlier is omitted. There is a general trend of poleward shifts of the ranges of the species in the Western Palaearctic compared to their native ranges. There are three reasons for these shifts: (1) the northward expansion of some species in Western Europe facilitated by the oceanic climate, (2) the impediment to the colonisation of southern latitudes in the Western Palaearctic due to their aridity and (3) the establishment of tropical species in the Mediterranean and the Middle East. Most of the species are small, not carnivorous and unlikely to cause serious ecological or economic damage. In contrast, the recently introduced large veronicellid slugs from Sub-Saharan Africa and the giant African snail Lissachatina fulica could cause economic damage in irrigated agricultural areas or greenhouses in the Mediterranean and the Middle East.

Review of the tribe Mutillini (Hymenoptera: Mutillidae) from the Oriental Region

The species in the tribe Mutillini (Mutillidae: Mutillinae) sensu Waldren et al. (2022, in press) of the Oriental region are reviewed. Fourteen species in the genera Kurzenkotilla Lelej, 2005, Mutilla Linnaeus, 1758, Standfussidia Lelej, 2005, and Storozhenkotilla Lelej, 2005 are keyed, reviewed, and illustrated. The males of the genus Kurzenkotilla are described and associated with the females. One new species: Storozhenkotilla nathani Lelej, sp. nov., male is described from India (Karnataka and Kerala). New combinations are proposed for Kurzenkotilla harmandi (André, 1898), comb. nov., K. rufodorsata (Cameron, 1897), comb. nov., K. semiviolacea (André, 1896), comb. nov., K. cicatricifera (André, 1894), comb. nov., and Storozhenkotilla binghami (Lelej, 2005), comb. nov. Six new country records are presented: Kurzenkotilla niveosignata (André, 1894) from Pakistan, K. annamensis Lelej, 2005 from Thailand, K. visrara (Cameron, 1898) from India, K. scrobiculata (Hammer, 1962) from Nepal, K. rufodorsata (Cameron, 1897) from Nepal, and Storozhenkotilla binghami Lelej, 2005 from Sri Lanka. Specimens of Mutilla mikado Cameron, 1900 from China were misidentified as Mutilla europaea by Su et al. (2019), and we recognize M. mikado as the sole member of the genus Mutilla to occur in the Oriental region. A key to the species of Oriental Mutillini is provided.

Love is in the air and beyond the ocean: Taxonomic review of Neotrogaspidia Lelej (Hymenoptera: Mutillidae: Trogaspidiini) in Northeast Asia highlights its unique distributional pattern

The genus Neotrogaspidia Lelej, 1996 is a small group of velvet ants with five species from the Australasian, Oriental and Palearctic Regions. The type species, N. pustulata (Smith, 1873) (♂♀), is the only Northeast Asian species known at present. In this paper, N. elpinice (Mickel, 1933), stat. resurr. et comb. nov. (♂♀) is resurrected from the junior synonym of N. pustulata. Two new combinations are proposed for N. circumcincta (André, 1896), comb. nov. (♂♀) from Orientidia Lelej, 1996 and N. recticarinata (Chen, 1957), comb. nov. (♂) from Trogaspidia Ashmead, 1899. New synonymies are proposed for N. elpinice with T. aestivalis Hammer, 1949, syn. nov. and T. maritima Chen, 1957, syn. nov., and N. circumcincta with T. yuliensis Tsuneki, 1972, syn. nov. and Krombeinidia agricola Williams, 2019, syn. nov. An updated genus diagnosis and a key to all described species are provided. New records include N. circumcincta from Laos and Vietnam, N. pustulata from North Korea, and N. recticarinata from Taiwan. The inflated endophallus of the male genitalia of N. pustulata is illustrated. A potential host record, habitat records and mating observations of Neotrogaspidia are presented. The historical process of formation of the distributional patterns of this genus in Northeast Asia is discussed.

The global spread and invasion capacities of alien ants

Many alien species are neither cultivated nor traded but spread unintentionally, and their global movements, capacities to invade ecosystems, and susceptibility to detection by biosecurity measures are poorly known.1,2,3,4 We addressed these key knowledge gaps for ants, a ubiquitous group of stowaway and contaminant organisms that include some of the world's most damaging invasive species.5,6,7,8,9,10 We assembled a dataset of over 146,000 occurrence records to comprehensively map the human-mediated spread of 520 alien ant species across 525 regions globally. From descriptions of the environments in which species were collected within individual regions-such as in imported cargoes, buildings, and outdoor settings-we determined whether different barriers to invasion had been overcome11 and classified alien ant species under three levels of invasion capacity corresponding to increasing biosecurity threat. We found that alien species of different invasion capacities had different sources and sinks globally. For instance, although the diversity of indoor-confined species peaked in the Palearctic realm, that of species able to establish outdoors peaked in the Nearctic and Oceanian realms, and these mainly originated from the Neotropical and Oriental realms. We also found that border interceptions worldwide missed two-thirds of alien species with naturalization capacity, many associated with litter and soil. Our study documents the vast spread of alien ants globally while highlighting avenues for more targeted biosecurity responses, such as prioritizing the screening of imports from regions that are diversity hotspots for species of high invasion capacity and improving the detection of cryptic alien invertebrates dwelling in substrates.

Spatial frequency representation in V2 and V4 of macaque monkey.

Spatial frequency (SF) is an important attribute in the visual scene and is a defining feature of visual processing channels. However, there remain many unsolved questions about how extrastriate areas in primate visual cortex code this fundamental information. Here, using intrinsic signal optical imaging in visual areas of V2 and V4 of macaque monkeys, we quantify the relationship between SF maps and (1) visual topography and (2) color and orientation maps. We find that in orientation regions, low to high SF is mapped orthogonally to orientation; in color regions, which are reported to contain orthogonal axes of color and lightness, low SFs tend to be represented more frequently than high SFs. This supports a population-based SF fluctuation related to the 'color/orientation' organizations. We propose a generalized hypercolumn model across cortical areas, comprised of two orthogonal parameters with additional parameters.