In this study, Akanthomyces comprised at least 36 species with a cosmopolitan distribution (Table 2). A collection of 31 isolates of unknown identity were shown to represent four known species, four new species, and an undetermined species of Akanthomyces. The phylogenetic positions of the four known species were evaluated based on phylogenetic inferences according to five loci, namely, ITS, nrLSU, TEF, RPB1, and RPB2, including A. araneogenus from China, Thailand, and Vietnam, A. dipterigenus and A. waltergamsii from China, and A. sulphureus from Vietnam (see Table 2 and Fig. 1). The four new species, given the names A. kunmingensis and A. subaraneicola from China, A. laosensis from Laos, and A. pseudonoctuidarum from Thailand, were recognized according to morphological characteristics and molecular data. The isolate YFCC 945 from China represented unknown species in the genus Akanthomyces. Unfortunately, the isolate did not produce conidia or reproductive structures when grown on PDA and other media, and they were thus tentatively treated as an undetermined species of Akanthomyces, pending further investigation.
Table 2
Species diversity, host–substrate and geographic distribution of Akanthomyces species
Species | Host/Substrate | Know Distribution | References |
Akanthomyces aculeatus | Amphipyra pyramidoides (Lepidoptera, Noctuidae); adult moth (Lepidoptera) | USA (Connecticut; Washington; Ontario); Brazil (Salvador) | Mains (1950) |
Akanthomyces angustispora | Coleopterous larva | USA (Nashville) | Mains (1950) |
Akanthomyces aranearum | Spider (Araneae) | USA (North Carolina; Maine); Ceylon; Netherlands; Ghana (Begoro); China | Mains (1950); Samson and Evans (1974); Hsieh et al. (1997); Zare and Gams (2001) |
Akanthomyces araneicola | Spider (Araneae) | China (Guizhou) | Chen et al. (2019) |
Akanthomyces araneogenus | Spider (Araneae) | China (Guizhou; Yunnan); Thailand (Chiang Mai); Vietnam (Nghe An) | Chen et al. (2018); This study |
Akanthomyces araneosus | Spider (Araneae) | China (Guizhou) | Chen et al. (2022) |
Akanthomyces attenuatus | Cydia pomonella (Lepidoptera, Tortricidae); leaf litter of Acer saccharum; Symplocarpus foetidus (plants); Astrocaryum sciophilum (plants) | Poland; USA; Canada; French | Zare and Gams (2001); Ellsworth et al. (2013); Barthélemy et al. (2019) |
Akanthomyces clavata | Hapithus agitator (Orthoptera, Gryllidae) | USA (Florida) | Mains (1950) |
Akanthomyces coccidioperitheciatus | Spider (Araneae) | Japan | Kepler et al. (2017); Johnson et al. (2009) |
Akanthomyces dipterigenus | Hemiptera: Icerya purchasi (Coccidae); Myzus persicae (Aphididae); Macrosiphoniella sanborni (Aphididae); Citrus aphid (Aphididae); soil | UK; Sri Lanka; Peru; China (Yunnan) | Kepler et al. (2017); Zare and Gams (2001); This study |
Akanthomyces fragilis | Orthopterous larva | Trinidad; Guiana; Brazil | Mains (1950); Petch (1937) |
Akanthomyces gracilis | Hymenoptera, Formicidae (Paltothyreus tarsatus; Platythyrea conradti; Polyrhachis militaris; Polyrhachis monista; Polyrhachis decemdentata; Camponotus brutus; Oecophylla longinoda; Crematogaster bequarti; Crematogaster clariventris; Macromischoides inermis; Macromischoides aculeatus; Dorylus sp.); Coleoptera (beetle larvae, beetle imago); Lepidoptera larva; Hemiptera (Pyrrhocoridae; Cercopidae) | Ghana (Begoro); China (Guizhou) | Samson and Evans (1974); Liang et al. (2013) |
Akanthomyces johnsonii | Leaf and stem (Arctium sp., Begonia sp., Coffea sp., Dianthus sp., Ipomoea sp., Kalanchoe sp., Lycopersicon sp., Peperomia sp., and Sargassum sp.); often associated with species of Botryosporium | Ghana; Indonesia; Australia (Great Barrier Reef); UK; USA; Canada | Vincent et al. (1988) |
Akanthomyces kanyawimiae | Spider (Araneae) | Thailand (Phetchabun; Chanthaburi) | Mongkolsamrit et al. (2018) |
Akanthomyces kunmingensis | Spider (Araneae) | China (Yunnan) | This study |
Akanthomyces laosensis | Adult moth (Lepidoptera, Noctuidae) | Laos (Oudomxay) | This study |
Akanthomyces lecanii | Hemiptera, Coccidae: Pulvinaria floccifera; Coccus viridis; scale insect. Tetranychus urticae (Acari: Tetranychidae); Pistacia vera (plants); Ammophila arenaria (plants); Dactylis glomerata (plants); Deschampsia flexuosa (plants); Elymus farctus (plants); Laretia acaulis (plants); Pinus sylvestris (plants); Shorea thumbuggaia (plants); Taxus baccata (plants) | W. Indies; Dominican Republic; Peru; Jamaica; USA; Sri Lanka; Indonesia; Turkey; China; Iran; Spain; Finland; Chile; Italy; Poland; India | Kepler et al. (2017); Zare and Gams (2001); Dash et al. (2018); Dolatabad et al. (2017); Nicoletti and Becchimanzi (2020) |
Akanthomyces lepidopterorum | Pupa of Lepidoptera | China (Guizhou) | Chen et al. (2020) |
Akanthomyces muscarius | Trialeurodes vaporariorum (Hemiptera, Aleyrodidae); Brachycaudus helichrysi (Hemiptera, Aphididae); Cecidophyopsis ribis (Acari, Eriophyidae); Cossus cossus (Lepidoptera, Cossidae ); Zyginidia pullula (Hemiptera, Cicadellidae); Thrips tabaci (Thysanoptera, Thripidae); peat; contaminated pesticide solution; Pteridium aquilinum (Pteridophyta); leaves of Nypa fruticans (Plants); Hemileia vastatrix (Fungi); water from domestic supply; laboratory glyphosate solution; Acer campestre (plants); Laurus nobilis (plants); Myrtus communis (plants); Nypa fruticans (plants); Quercus robur (plants); Prunus cerasus (plants); cabbage plants | UK; Italy; New Caledonia; Thailand; New Zealand | Kepler et al. (2017); Zare and Gams (2001); Nicoletti and Becchimanzi (2020); Vinit et al. (2018); Aghdam et al. (2017); Kuchár et al. (2019) |
Akanthomyces neoaraneogenus | Spider (Araneae) | China (Guizhou) | Chen et al. (2017); Mains (1949) |
Akanthomyces neocoleopterorum | Ladybug (Coleoptera) | China (Guizhou) | Chen et al. (2020) |
Akanthomyces noctuidarum | Adult moth (Lepidoptera, Noctuidae) | Thailand (Narathiwat; Nakhon Ratchasima; Kamphaeng Phet) | Aini et al. (2020) |
Akanthomyces pissodis | Adult of Pissodes strobi (Coleoptera, Curculionidae) | Canada | Chen et al. (2020); Cope and Leal (2005) |
Akanthomyces pseudonoctuidarum | Adult moth (Lepidoptera, Noctuidae) | Thailand (Chiang Mai) | This study |
Akanthomyces pyralidarum | Adult moth (Lepidoptera, Pyralidae) | Thailand (Kanchanaburi; Chiang Mai; Phetchabun) | Aini et al. (2020) |
Akanthomyces ryukyuenis | Spider (Araneae) | Japan | Kobayasi and Shimizu (1982) |
Akanthomyces sabanensis | Pulvinaria caballeroramosae (Hemiptera, Coccidae) | Colombia | Kepler et al. (2017); Chiriví-Salomón et al. (2015) |
Akanthomyces subaraneicola | Spider (Araneae) | China (Hunan; Yunnan) | This study |
Akanthomyces sulphureus | Spider (Araneae) | Thailand (Nakhon Ratchasima; Surat Thani); Vietnam (Nghe An) | Mongkolsamrit et al. (2018); This study |
Akanthomyces thailandicus | Spider (Araneae) | Thailand (Chiang Mai) | Mongkolsamrit et al. (2018) |
Akanthomyces tiankengensis | Spider (Araneae) | China (Guizhou) | Chen et al. (2022) |
Akanthomyces tortricidarum | Adult moth (Lepidoptera, Tortricidae) | Thailand (Nakhon Ratchasima; Kamphaeng Phet) | Aini et al. (2020) |
Akanthomyces tuberculatus (= A. pistillariaeformis) | Adult moth (Lepidoptera); Hymenoptera, Formicidae; Hemiptera, Pyrrhocoridae | China (Zhejiang; Yunnan); Begoro; Trinidad | Mains (1950); Samson and Evans (1974); Liang et al. (2007) |
Akanthomyces uredinophilus | Rust; decayed insect | Korea (Gangwon; North Chungcheong); China (Yunnan) | Park et al. (2016); Wei et al. (2018) |
Akanthomyces waltergamsii | Spider (Araneae) | Thailand (Saraburi; Naknon Ratchasima); China (Yunnan) | Mongkolsamrit et al. (2018); This study |
Akanthomyces zaquensis | The stroma and the sclerotium of Ophiocordyceps sinensis (Fungi) | China (Qinghai) | Wang et al. (2013) |
Boldface: data generated in this study. |
Formal descriptions of the five Akanthomyces species
Akanthomyces araneogenus Z.Q. Liang, W.H. Chen and Y.F. Han, Phytotaxa 379(1): 69 (2018). (Fig. 2)
MycoBank: MB816114.
Description: Sexual morph: Undetermined. Asexual morph: See Chen et al. (2018). The descriptions that follow are based on other examined specimens that were obtained from Thailand and Vietnam. Mycosed hosts covered with white to pale yellow mycelia, occasionally several synnemata arise from all of the parts of the host. Colonies on PDA moderately fast-growing at 25°C, reaching a diameter of 25–36 mm in 14 days at 25°C, circular, middle bulge, white to yellowish, reverse yellowish. Hyphae smooth-walled, branched, septate, hyaline, 0.5–2.9 µm wide. Conidiophores smooth‐walled, cylindrical, solitary, 10.6–22.4 × 1.3–2.6 µm (n = 30). Phialides consisting of a cylindrical, somewhat inflated base, verticillate on conidiophores, usually in whorls of 2–3, or solitary on hyphae, 8.1–17.8 × 1.1–3.6 µm (n = 30). Conidia smooth and hyaline, one‐celled, globose, 1.6–2.4 µm in diameter, or ellipsoidal to fusiform, 2.2–4.1 × 1.1–2.3 µm (n = 50), often in chains. Size and shape of phialides and conidia similar in culture and on natural substratum.
Host
Spider (Araneae).
Habit
On the spiders on dead stems or emerging from leaf litter.
Distribution
Guizhou and Yunnan Province, China; Chiang Mai Province, Thailand; Nghe An Province, Vietnam.
Material examined: Thailand, Chiang Mai Province, Chiang Mai City, Queen Sirikit Botanic Garden (18.8990°N, 98.8604°E, 547 m above sea level), on a spider on a dead stem, November 20, 2018, Yao Wang (YHH 2301001; living culture: YFCC 1811934). Vietnam, Nghe An Province, Pu Mat National Park (18.9292°N, 104.5889°E, 621 m above sea level), on spiders emerging from leaf litter on the forest floor, April 28, 2017, Yao Wang (YHH 2301007, YHH 2301012; living culture: YFCC 1704946, YFCC 1704947). China, Yunnan Province, Dai Autonomous Prefecture of Xishuangbanna, Mengla County (21.1817°N, 101.7252°E, 875 m above sea level), on a spider on a dead stem, June 12, 2022, Zhi-Qin Wang (YHH 2301002; living culture: YFCC 2206935).
Commentary
In our phylogenetic analyses, A. araneogenus ex-type strain (GZUIF DX2) and A. tiankengensis ex-type isolate (KY11571) and our two samples isolated from the spiders formed a well-supported clade (Fig. 1). From a phylogenetic point of view, A. tiankengensis could not be distinguished from A. araneogenus, being inside the clade of the latter. Morphologically, previous morphological observations revealed several differences in the characteristics between A. araneogenus and A. tiankengensis, except they share the same hosts (Chen et al. 2018; Chen et al. 2022); however, our samples from different regions showed diversity of morphology in this study. The colony color and the shape and size of the phialides and conidia of A. araneogenus and A. tiankengensis among other morphological features have been noted in our samples. There is reason to believe that distinguishing the two species is difficult because of the extensive overlap in morphological characteristics. Thus, we propose that A. tiankengensis is a synonym of A. araneogenus.
Akanthomyces kunmingensis H. Yu bis, Y. Wang & Z.Q. Wang, sp. nov. (Fig. 3)
MycoBank: MB848307.
Etymology
Named after the location, Kunming City, where the species was collected.
Type: China, Yunnan Province, Kunming City, Wild Duck Lake Forest Park (25.2181°N, 102.8503°E, 2100 m above sea level), on a spider on a dead stem, August 14, 2018, collected by Yao Wang (holotype: YHH 16988; ex-type living culture: YFCC 1808940).
Description: Sexual morph: Undetermined. Asexual morph: Synnemata arising from spider body, cream to light yellow, erect, irregularly branched, producing a mass of conidia at the upper apex, powdery and floccose. Colonies on PDA reaching 15–20 mm in diameter after 14 days at 25°C, circular, white, and fluffy mycelium, middle bulge, reverse pale yellow to light brown. Hyphae smooth-walled, branched, septate, hyaline, 0.5–2.8 µm wide. Conidiophores smooth‐walled, cylindrical, solitary, sometimes verticillate, 4.3–9.5 × 1.2–2.0 µm (n = 30). Phialides consisting of a cylindrical, somewhat inflated base, verticillate on conidiophores, usually in whorls of 4–5, or solitary on hyphae, 6.2–29.4 × 1.1–2.5 µm (n = 30). Conidia smooth and hyaline, ellipsoidal to long oval, one‐celled, 1.9–3.5 × 1.1–1.8 µm (n = 50), often in chains. Size and shape of phialides and conidia similar in culture and on natural substratum.
Host
Spider (Araneae).
Habit
On spiders on dead stems.
Distribution
At present known only from Kunming City, Yunnan Province, China.
Other material examined: China, Yunnan Province, Kunming City, Songming County, Dashao Village (25.3924°N, 102.5589°E, 2700 m above sea level), on a spider on a dead stem, August 12, 2017, Yao Wang (YHH 2301006; living culture: YFCC 1708939).
Commentary
In regard to phylogenetic relationships, A. kunmingensis forms a distinct lineage in the genus Akanthomyces, and it is closely related to A. sulphureus and A. waltergamsii (Fig. 1). Morphologically, A. kunmingensis is so similar to A. waltergamsii that it was once referred to as A. waltergamsii by us (Wang et al. 2020); however, a morphological observation revealed a significant difference of conidia shapes between A. kunmingensis and A. waltergamsii. Akanthomyces kunmingensis usually produces a variety of shapes of conidia (viz., spherical, ellipsoidal to long oval, or fusiform), while A. waltergamsii produces only ellipsoidal and fusiform conidia. Moreover, A. kunmingensis can be distinguished from A. sulphureus and A. waltergamsii by its longer phialides (6.2–29.4 µm) and smaller conidia (1.9–3.5 × 1.1–1.8 µm) (Table 3).
Table 3
Morphological comparison of Akanthomyces species
Species | Perithecia (µm) | Asci (µm) | Part-spores (µm) | Synnemata (mm) | Conidiophores (µm) | Phialides (µm) | Conidia (µm) | References |
Akanthomyces aculeata | | | | Arising from various parts of the insect, terete, narrowing upward, 1–8 × 0.1–0.5, yellowish | | Subcylindric or narrowly ellipsoid, 6–16 × 2.5–4, narrowing above to an acute apex terminated by a short sterigma up to 4 long | Broadly ellipsoid or obovoid often acute at the lower end, 3–6 × 2–3 | Mains (1950) |
Akanthomyces aranearum | | | | Arising from all parts of the host, cylindric to clavate, 0.8–10 × 0.1–0.2, simple or occasionally slightly branched, brown | | Obovoid or ellipsoid 6–12 × 4–8, rounded above and abruptly narrowing into a short sterigma, asperulate | Narrowly obclavate often acute at the lower end, narrowing upward, rounded or obtuse at the upper end, 8–14 × 1.5–3 | Mains (1950) |
Akanthomyces araneicola | | | | Synnemata not observed | Mononematous, with single phialide or whorls of two to six phialides, or Penicillium-like from hyphae directly | Cylindrical, somewhat inflated base, 8.1–16.9 × 1.3–1.9, tapering to a thin neck | Mostly fusiform, 2.5–5.0 × 1.3–1.9 | Chen et al. (2019) |
Akanthomyces araneogenus | | | | Occasionally several white synnemata arise from all parts of the host | Mononematous or synnematous, 21.6–48 × 1.2–2.2, Penicillium-like from hyphae directly | Cylindrical, somewhat inflated base, 4.3–17.3 × 0.9–3.1, tapering to a thin neck | Globose, 1.3–2.4 in diam, or ellipsoid, 2.1–3.3 × 1.1–1.6 | Chen et al. (2018) |
Akanthomyces araneosus | | | | Synnemata not observed | Erect conidiophores usually arose from the aerial hyphae | Solitary or in groups of two, 16.9–18.1 × 1.3–1.9 with a cylindrical basal portion and tapered into a short, distinct neck | Fusiform, 3.1–5.0 × 1.0–1.8 | Chen et al. (2022) |
Akanthomyces angustispora | | | | Arising from the body and head of the host, simple or branched, 8–13 × 0.2–0.6, flesh colored | | Oblong or narrowly ellipsoid, 6–14 × 3–4, narrowing above into an acute apex terminated by a short sterigma | Narrowly clavate, 4.5–6 × 1.2–1.4 | Mains (1950) |
Akanthomyces attenuatus | | | | | | 9–15.5 × 1–2 | Cylindrical with attenuate base, occasionally 2-celled, 4.5–6.5 × 1.5–2.0 | Kepler et al. (2017); Zare and Gams (2001) |
Akanthomyces clavata | | | | Numerous, arising from various parts of the host, light brown, clavate, 0.5–2.0 × 0.06–0.25 | | Subcylindric, 17.1–21.4 × 2.8–4.3, narrowing above to acute apices, terminated by short sterigmata | Ellipsoid to oblong, 4.5–8.5 × 2.1–2.5 | Mains (1950) |
Akanthomyces dipterigenus | | | | | | 20–40 × 1.2–2.7, tapering towards the apex | Ellipsoidal to oblong-oval, 5.0–10.5 × 1.5–2.5 | Kepler et al. (2017); Zare and Gams (2001) |
Akanthomyces fragilis | | | | Numerous arising from all parts of the host, clavate, 0.7–1.5 × 0.03–0.09 | | Subcylindric to narrowly clavate, 7–10 × 2.5–3, verrucose in the upper portions | Subcylindric, somewhat narrowed and rounded at the ends, 6.5–9 × 1.5 | Mains (1950) |
Akanthomyces gracilis | | | | Arising from the natural body openings and intersegmental and appendage joints, usually white to yellow-brown, cylindrical, 0.7–3 × 0.1–0.5 | | Cylindrical basal part tapering to a slender neck, 7–10 × 1.5–2.5 | Ellipsoidal to fusiform, 2.5–3 × 1–1.6 | Samson and Evans (1974) |
Akanthomyces johnsonii | | | | Gregarious, white, 0.4–4 tall, with a stipe 0.025–0.1 wide, subulate to cylindrical | Unbranched or with metulae arising at right angles to the stipe hyphae, 4–6 × 2–3 | 10–20 long, ellipsoidal to cylindrical body 2.5–4 wide, tapering into a narrow neck 3–5 × 1–1.5 | Broadly fusoid with more or less truncate poles with minute frills, 3–4 × (l–)1.5–2 | Vincent et al. (1988) |
Akanthomyces kanyawimiae | | | | Up to 1.5 long, up to 0.4 wide, covered by dense white to cream mycelia | Erect, verticillate with phialides in whorls of two to five | (8–)9–12(–15) × 2–3, with cylindrical basal portion,tapering into a long neck, (2–)3–5.5(–7) × 1–1.5 | Cylindrical to ellipsoidal, (2–)2.5–3.5(–5) × (1.5–)2(–3) | Mongkolsamrit et al. (2018) |
Akanthomyces kunmingensis | | | | Cream to light yellow, erect, irregularly branched | Cylindrical, solitary, sometimes verticillate, with phialides in whorls of four to five 4.3–9.5 × 1.2–2.0 | Cylindrical, somewhat inflated base, 6.2–29.4 × 1.1–2.5 | Ellipsoidal to long oval, 1.9–3.5 × 1.1–1.8 | This study |
Akanthomyces laosensis | | | | Arising at the head and in the middle of the host body, white, up to 15.6 long, 0.6–1.3 wide, feathery to clavate with acute or blunt end | Monophialidic, produced along the synnemata, or solitary on hyphae in culture | Cylindrical, 11.5–30.0 × 2.0–4.2 | Cylindrical or long oval, 4.1–9.8 × 2.3–4.2 | This study |
Akanthomyces lecanii | Ovoid, 350–650 × 200–375 | 200–350 × 3.5–4 | | | | Relatively short, 11–20(–30) × 1.3–1.8, aculeate and strongly tapering | Typically short-ellipsoidal, 2.5–3.5(–4.2) × 1–1.5 | Kepler et al. (2017); Zare and Gams (2001); Shrestha et al. (2019) |
Akanthomyces lepidopterorum | | | | Synnemata not observed | Mononematous, with single phialide or two phialides | Cylindrical, somewhat inflated base, 12.7–25.8 × 1.4–1.7, tapering to a thin neck | Mostly cylindrical, 3.5–5.6 × 1.4–2.1, forming mostly globose heads | Chen et al. (2020) |
Akanthomyces muscarius | | | | | | (15–)20–35 × 1.0–1.7 | Ellipsoidal to subcylindrical, (2–)2.5–5.5(–6) × 1–1.5(–1.8) | Kepler et al. (2017); Zare and Gams (2001) |
Akanthomyces neoaraneogenus | | | | Synnemata not observed | Moderately branched, with (1–)2–6 (–8) phialides | 30–64 × 1.1–3.2 | Forming mostly globose heads, cylindric, 3.2–8.6 × 1.3–1.6 | Chen et al. (2017); Mains (1949) |
Akanthomyces neocoleopterorum | | | | Synnemata not observed | Mononematous, with single phialide or whorls of two to five phialides, or Verticillium-like from hyphae directly | Cylindrical, somewhat inflated base, 19.9–29.6 × 1.6–2.0, tapering to a thin neck | Mostly cylindrical, 3.3–6.6 × 1.5–1.8 | Chen et al. (2020) |
Akanthomyces noctuidarum | Ovoid, (530–)623–993(–1000) × (290–)308–413(–425) | (170–)196–423(–550) × (2–)2.7–3.8(–4) | (6–)7–10.7(–13) × 1 | Arising from moth body and wing veins, white to cream, erect, cylindrical to clavate, (650–)668–1191(–1500) × (50–)53.4–102(–120) µm | Monophialidic or polyphialidic | Cylindrical with papillate end, hyaline, (5–)6.8–9(–10) × (1.8–)2–2.4(–3) | Cylindrical with round end, (3–)3.5–4.5(–6) × 1 | Aini et al. (2020) |
Akanthomyces pissodis | | | | Synnemata not observed | | | Cylindrical to ovoid or oval, 4–9.2 × 1.6–2.4 | Chen et al. (2020); Cope and Leal (2005) |
Akanthomyces pseudonoctuidarum | | | | Arising from moth body, cream to light yellow, erect, cylindrical to clavate, 0.8–2 × 0.12–0.35 | Cylindrical, solitary, 6.5–13.8 × 1.8–3.6 | Cylindrical with papillate end, 6.8–26.0 × 2.1–3.6 | Ellipsoidal to long oval, 2.6–6.4 × 1.5–2.2 | This study |
Akanthomyces pyralidarum | Ovoid to obpyriform, (290–)342–580(–650) × (150–)186–291(–340) | (170–)222–329(–360) × (2–)2.5– 3.3(–4) | (5–)5.9–9.4(–12) × 1 | Synnemata not observed | Not observed | Not observed | Not observed | Aini et al. (2020) |
Akanthomyces ryukyuenis | Pyriformia, 570–630 × 170–250 | 5 wide, cap 3 wide | 1 × 1–4 | | | | | Kobayasi et al. (1982) |
Akanthomyces sabanensis | | | | Synnemata not observed | Generally arising from submerged hyphae, moderately branched | Solitary or in whorls of 2–4, 13–19 long, from 1.0–2.0 gradually tapering to 0.5–1.0 | Ellipsoidal to ovoid, usually straight, 3.5–4.5 × 1.5–2.0 | Kepler et al. (2017); Chiriví-Salomón et al. (2015) |
Akanthomyces sulphureus | Narrowly ovoid, (650–)676(–680) × (240–)324.5(–330) | Up to 500 long, 2–3 wide | (300–)336(–450) × 1–1.5 | Synnemata not observed | Erect, verticillate with phialides in whorls of two to three | (10–)16(–20) × 2–2.5, with a cylindrical basal portion, tapering into a thin neck, 1 × 0.5 | Cylindrical to ellipsoidal, (4–)4.5–5.5(–6) × 2–3 | Mongkolsamrit et al. (2018) |
Akanthomyces subaraneicola | | | | Synnemata not observed | Cylindrical, solitary or verticillate with phialides in whorls of two to five, 6.5–12.3 × 1.6–3.5 | Cylindrical, somewhat inflated base, 12.1–38.2 × 1.3–3.2 | Ellipsoidal to long oval, 3.0–5.4 × 1.8–3.4 | This study |
Akanthomyces thailandicus | Narrowly ovoid, (700–)752–838(–850) × (300–)305–375(–400) | Up to 550 long, 5–7 wide | 4–6 × 1–1.5 | Synnemata not observed | Erect, forming verticillate branches with solitary phialides | (12–)13.5–21(–30) × 1–2, awl-shaped, lecanicillium-like | Cylindrical to ellipsoidal (3–)4–6(–7) × 1.5–2 | Mongkolsamrit et al. (2018) |
Akanthomyces tiankengensis | | | | Synnemata not observed | Erect, usually arose from the aerial hyphae | Solitary or in groups of two, 13.9–17.1 × 1.1– 1.6 with a cylindrical basal portion and tapered into a short, distinct neck | Fusiform, 2.3–3.0 × 1.5–2.3 | Chen et al. (2022) |
Akanthomyces tortricidarum | | | | Long synnemata arose at the head and in the middle of the host body, up to 5 long, 0.12–0.15 wide, cylindrical to clavate, short synnemata arose on moth body, wings, and legs, (197–)200–267(–300) × (15–)17.7–31.6(40–)µm, white to cream | Monophialidic or polyphialidic | Long synnemata: (5–)6–8(–10) × (1.8–)2–2.7(–3), short synnemata: (5–)6.2–8.3(–10) × (1.8–)2–2.5(–3), cylindrical to ellipsoidal with papillate end | Fusoid, long synnemata: (1–)2.5–3(–3.2) × (0.8–)1–1.4(–2), short synnemata: (1–)1.8–2.7(–3) × 1–2 | Aini et al. (2020) |
Akanthomyces tuberculatus (= A. pistillariaeformis) | Narrowly ovoid or conoid, 420–900 × 180–370 | 300–600 × 4–5 | 2–6 × 0.5–1 | Arising from all parts of the moths, clavate, 0.4–1.0 long, the stipe 0.025–0.05 thick | | Subcylindric, 6–10 × 2–3, narrowing above into an acute apex terminated by a short sterigma 2–3 long | Fusoid to subcylindric narrowing at the ends, 2.5–5 × 1–1.5 | Mains (1950) |
Akanthomyces uredinophilus | | | | Synnemata not observed | | Produced singly or in whorls of up to 3–4(–5) on prostrate hyphae, 20–60 × 1–2.5(–3) | Cylindric, oblong, or ellipsoid, 3–9 × 1.8–3 | Park et al. (2016) |
Akanthomyces waltergamsii | | | | Arising on legs of spider, erect, up to 1.5 long, 0.1–0.12 wide | Usually forming verticillate branches with phialides in whorls of two to five | (10–)16(–22) × (1–)1.5(–2), with cylindrical to ellipsoidal basal portion, tapering into a thin neck, 1–3 × 1 | Ellipsoidal or fusiform, (2–)3.5(–4) × 2–3 | Mongkolsamrit et al. (2018) |
Akanthomyces zaquensis | | | | Synnemata not observed | | 8.0–40.0 long, rarely over 100, 0.6–1.2 at the base, tapering to about 0.4 at the tips | Long-ellipsoidal to almost cylindrical, (1.5–)3.0–6.0(–7.0) × 0.5–1.2(–1.5) | Wang et al. (2013) |
Boldface: data generated in this study. |
Akanthomyces laosensis H. Yu bis & Y. Wang, sp. nov. (Fig. 4).
MycoBank: MB848308.
Etymology
Named after the location, Laos, where the species was collected.
Type: Laos, Oudomxay Province, Muang Xay County, Nagang Village (20.7143°N, 102.0957°E, 698 m above sea level), on the adult of Noctuidae on the underside of a dicotyledonous leaf, October 5, 2019, collected by Yao Wang (holotype: YHH 2301008; ex-holotype living culture: YFCC 1910941).
Description: Sexual morph: Undetermined. Asexual morph: Specimens examined in this study can be found on the underside of dicotyledonous leaves. Synnemata arose at the head and in the middle of the host body, white, up to 15.6 mm long and 0.6–1.3 mm wide, rarely branched, feathery to clavate with acute or blunt ends. Colonies on PDA moderately fast-growing at 25°C, reaching 23–26 mm in diameter in 14 days, circular, flat, white in the middle with a light yellow edge, reverse light yellow. Hyphae smooth-walled, branched, septate, hyaline, 0.8–3.5 µm wide. Conidiogenous cells monophialidic, produced along the synnemata, or solitary on hyphae in culture. Phialides smooth-walled, hyaline, cylindrical, 11.5–30.0 × 2.0–4.2 µm (n = 30). Conidia smooth and hyaline, cylindrical or long oval, one-celled, 4.1–9.8 × 2.3–4.2 µm (n = 30). Size and shape of phialides and conidia similar in culture and on natural substratum.
Host
Adult moth (Noctuidae, Lepidoptera).
Habit
On the adults of Noctuidae sp. on the underside of leaves of plants.
Distribution
Muang Xay County, Oudomxay Province, Laos.
Other material examined: Laos, Oudomxay Province, Muang Xay County, Nam Kit Park (20.6651°N, 102.0007°E, 695 m above sea level), on an adult moth on the underside of a leaf, October 1, 2019, Yao Wang (YHH 2301000; living culture: YFCC 1910942).
Commentary
Phylogenetically, A. laosensis forms a distinct lineage and is closely related to A. pyralidarum (Fig. 1). Morphologically, A. laosensis is distinctly different from A. pyralidarum because of its longer synnemata (up to 15.6 mm). Furthermore, A. laosensis was determined to occur on an adult of Noctuidae sp., while A. pyralidarum was located on an adult of Pyralidae sp. In fact, the species is easily distinguished from other known species in the genus of Akanthomyces by its longer phialides (11.5–30.0 µm) and larger conidia (4.1–9.8 × 2.3–4.2 µm) (Table 3).
Akanthomyces pseudonoctuidarum H. Yu bis & Y. Wang, sp. nov. (Fig. 5)
MycoBank: MB848309.
Etymology
Referring to macromorphological resemblance of A. noctuidarum and A. pseudonoctuidarum but phylogenetically distinct.
Type: Thailand, Chiang Mai Province, Chiang Mai City, Maejo Farm (18.9177°N, 99.0520°E, 317 m above sea level), on the adult of Noctuidae on the underside of a dicotyledonous leaf, August 22, 2018, collected by Hong Yu (holotype: YHH 2301010; ex-type living culture: YFCC 1808943).
Description: Sexual morph: Undetermined. Asexual morph: Synnemata arising from moth body, cream to light yellow, erect, simple, cylindrical to clavate, 800–2000 × 120–350 µm. Conidia and reproductive structures on natural substratum not observed. Colonies on PDA moderately fast-growing at 25°C, reaching a diameter of 25–28 mm within 14 days, circular, flat to raised, white and fluffy mycelium, reverse cream to pale yellow. Hypha smooth-walled, hyaline, septate, 1.0–2.9 µm wide. Conidiophores smooth-walled, cylindrical, solitary, 6.5–13.8 × 1.8–3.6 µm (n = 30). Conidiogenous cells monophialidic or polyphialidic. Phialides verticillate, usually in whorls of 2–3, or solitary on hyphae, cylindrical with papillate end, hyaline, 6.8–26.0 × 2.1–3.6 µm (n = 30). Conidia smooth and hyaline, ellipsoidal to long oval, one-celled, 2.6–6.4 × 1.5–2.2 µm (n = 30).
Host
Adult moth (Noctuidae, Lepidoptera).
Habit
On the adults of Noctuidae sp. on the underside of leaves of plants.
Distribution
Currently only known in Chiang Mai City, Chiang Mai Province, Thailand.
Other material examined: Thailand, Chiang Mai Province, Chiang Mai City, Queen Sirikit Botanic Garden (18.8990°N, 98.8605°E, 536 m above sea level), on an adult of Noctuidae, August 26, 2018, Yao Wang (YHH 2301011; living culture: YFCC 1808944).
Commentary: Akanthomyces pseudonoctuidarum is similar to its phylogenetically closely related species A. noctuidarum in macromorphology. They have the same hosts (the adults of Noctuidae sp.) and Isaria-like asexual conidiogenous structures, producing cream or light yellow synnemata; however, A. pseudonoctuidarum is easily recognized by its larger synnemata (800–2000 × 120–350 µm), longer phialides (6.8–26.0 µm), and larger conidia (2.6–6.4 × 1.5–2.2 µm) (Table 3). It was easily distinguished phylogenetically from A. noctuidarum (Fig. 1). Both the morphological study and phylogenetic analyses of combined ITS, nrLSU, TEF, RPB1, and RPB2 sequence data supported that this fungus is a distinct species in the genus Akanthomyces.
Akanthomyces subaraneicola H. Yu bis, Y. Wang & Z.Q. Wang, sp. nov. (Fig. 6)
MycoBank: MB848310.
Etymology
“Subaraneicola” refers to morphologically resembling A. araneicola but phylogenetically distinct.
Type: China, Hunan Province, Huaihua City, Zhongpo National Forest Park (27.5724°N, 109.9664°E, 615 m above sea level), on a spider emerging from leaf litter on the forest floor, July 10, 2021, collected by Yao Wang (holotype: YHH 2301004; ex-type living culture: YFCC 2107937).
Description: Sexual morph: Undetermined. Asexual morph: Mycosed hosts covered by white to pale yellow mycelia, producing numerous powdery conidia, synnemata not observed. Colonies on PDA reaching 24–28 mm in diameter within 14 days at 25°C, circular, white, and fluffy mycelium in the center, cottony with a raised mycelial density at the outer ring, reverse white to pale yellow. Hyphae smooth-walled, branched, septate, hyaline, 1.6–3.2 µm wide. Conidiophores smooth‐walled, cylindrical, solitary, sometimes verticillate, 6.5–12.3 × 1.6–3.5 µm (n = 30). Conidiogenous cells monophialidic or polyphialidic. Phialides consisting of a cylindrical, somewhat inflated base, verticillate on conidiophores, usually in whorls of 2–5, or solitary on hyphae, 12.1–38.2 × 1.3–3.2 µm (n = 30). Conidia smooth and hyaline, ellipsoidal to long oval, one‐celled, 3.0–5.4 × 1.8–3.4 µm (n = 50), often in chains. Size and shape of phialides and conidia similar in culture and on natural substratum.
Host
Spider (Araneae).
Habit
On spiders on dead stems or emerging from leaf litter on the forest floor.
Distribution
Hunan and Yunnan Province, China.
Other material examined: China, Yunnan Province, Kunming City, Wild Duck Lake Forest Park (25.1244°N, 102.8716°E, 1900 m above sea level), on a spider on a dead stem, July 28, 2021, Yao Wang (YHH 2301005; living culture: YFCC 2107938).
Commentary
Morphologically, A. subaraneicola resembles the phylogenetic sister species A. araneicola. They were found to be parasitic on spiders (Araneae), and they are easily recognized by having white to pale yellow mycelia covering the hosts with a mass of conidia; however, our morphological observation revealed a significant difference in the shape and size of conidia between A. subaraneicola and A. araneicola. Akanthomyces subaraneicola usually produces large ellipsoidal to long oval conidia (3.0–5.4 × 1.8–3.4), while A. araneicola produces small fusiform conidia (2.5–5.0 × 1.3–1.9 µm) (Table 3). In addition, molecular phylogenetic analyses indicated that they are distinct species (Fig. 1).