(Panephemeroptera Euephemeroptera Euplectoptera Posteritorna - Prosopistoma/f1=g2)

Nomen hierarchicum: Prosopistoma/f1=g2 [f:1917; g:1833] (sine Baetisca).

In circumscription fits:

gen. Prosopistoma Latreille 1833: 33

gen. Chelysentomon Joly & Joly 1872: 438

gen. Binoculus: Demoulin 1954b: 102

tribus Prosopistomini: Lameere 1917: 75

fam. Prosopistomidae: Lestage 1917: 240

fam. Binoculidae Demoulin 1954b: 103

Prosopistoma/f1=g2: Kluge 2004: 63

Synonym: objective synonym of Prosopistoma is Chelysentomon/g [g:1872]

Nominal taxon included: Binoculus/fg [fg:1954] (nom. praeocc.).

References. Vayssiere 1881: ; 1890: ; Eaton 1883-1888: ; Lestage 1917: ; Lafon 1953: ; Gillies 1954:  ; 1956:  ; Tshernova 1970:  ; Kluge 2004:  * * *.

Autapomorphies of Prosopistoma/f1=g2.

(1) Mouth apparatus is strongly modified and specialized for carnivorism (Eaton 1883-1888: Pl.43:4-8). Labrum is widened. Asymmetry of mandibles is lost; mandible is strongly elongate along axis of its articulation, mola is completely lost (less complete reduction of mola took place in some other carnivorous mayflies). Superlinguae are completely lost (the same in some other carnivorous mayflies). Maxilla [see Posteritorna (7)] has a single long canine (instead of initial three ones) and 3 dentisetae, which being pressed to canine, form something like an integral claw (Kluge 2004: Fig.15:A). 2nd segment of maxillary palp is curved so that its inner side is convex. Submentum is very strongly enlarged, its lateral lobes [see Posteritorna (7)] are projected forward, covering from below lateral parts of the rest of labium with labial palps, and anteriorly they reach labrum and anterior-lateral margins of head (unique apomorphy); mentum, glossae and paraglossae are fused forming an integral plate widened distally. Variuos species can be either really carnivorous, or eat detritus and algae (Fontaine 1980).

(2) Larva has lens-like body form (Kluge 2004: Fig.15:B; Eaton 1883-1888: Pl.43:1-2): head is strongly widened, with rounded anterior margin; lateral margins of notal shield [see Posteritorna (3)] are rounded, without projections (unlike Baetisca/f2=g1); when abdominal segments VII-X and caudalii are retracted [see (3)], larval body together with head in dorsal view has a shape of regular oval; dorsally it is evenly convex with median longitudinal keel on notal shield, ventrally flat. Integrity of flat ventral surface is completed by expanded mentum covering mouthparts from below [see (1)]. Abdominal segments up to VI inclusively are fused immobile one with another and with thorax; while dorsally they are separated by sutures, ventrally only suture between segments V and VI is retained. Lateral margins of segment V have a pair of incisions; thus, between this segment and epipleura [see Posteritorna (3)] there is a pair of distinctly outlined apertures, which lead to a gill chamber. Femora can be inserted into concavities on thorax and abdomen, and concavities for hind femora convergent posteriorly under acute angle in area of abdominal sternum IV. 

(3) Abdominal segment X and caudalii have unique structure (Kluge 2004: Fig.15:B). Larval and imaginal tergite X and paraprocts are elongate, rectangular, paraprocts are expanded behind bases of caudalii. Larval (but not imaginal) caudalii can be completely retracted inside abdomen thanks to a pair of long apodemes, which stretch from anterolateral angles of tergite X anteriorly and serve for attachment of the tergal-caudalial muscles.

(4) Winged stages are short-living; moult to imago takes place in males only; all legs of female and of male imago, including fore legs, are diminished and non-functional (only in male subimago legs are functional, serving moult on substrate). Non-unique apomorphy (see Index of characters [2] and [2.2.80]). In male tarsi are 2-segmented, first of these segments is fused with tibia, each leg has a single blunt claw; female legs are reduced in greater degree. Like in other short-living mayflies, subimaginal cuticle is entirely thin and colourless, without pigmented areas (Kluge 2004: Fig.16:D).

(5) Wing venation is strongly modified, unique (Kluge 2004: Fig.16:A-C). Crossveins are completely lost both on fore and hind wings. Fore wing has only veins radiating from base in a fan-form manner; RSa and RSp begin near wing base independently, i.e. have a form of intercalaries; RSa is non-branching (only sometimes female has vestige of RSa1 arising anteriorly from RSa; MA lacks furcation, thus MA2 is lost. In female on fore wing intercalaries are lost besides iRS and iMP (which begin near wing base and look like other longitudinal veins). In male two long intercalaries are present by sides of each of fan-form radiating veins (RSa, iRS, RSp, MA, MP1, iMP, MP2, CuA, CuP, AA) and several intercalaries are present before RSa and behind AA. Intercalaries bordering longitudinal veins are new formations absent in other mayflies. Hind wing has similar structure in male and female, narrow, with costal projection transferred proximally, with numerous fan-form intercalaries, which can be hardly homologized. 

(6) In imago [which is present in male only see (4)] amphitornal margin of wing bears setae; these setae are smaller
than in subimago or in female and unlike them, are present on a part of setae-bearing tubercles only (Kluge 2004: Fig.16:B-C). Non-unique apomorphy (see Index of characters [2.2.27]).

(7) Imaginal and subimaginal mesonotal suture is strongly curved posteriorly on each side; only its median portion is expressed as a pair of sutures, diverging from middle line backward under acute angle (Kluge 2004: Fig.16:F). Non-unique apomorphy (see Index of characters [2.2.8]). 

(8) Male imaginal eyes are not enlarged, as small as in female (non-unique apomorphy see Index of characters [2.1.3]). In both sexes eyes are small, spherical, widely separated, with narrow bases (Gillies 1954: Fig.14)

Character of Prosopistoma/f1=g2 of unclear phylogenetic status. 

(9) In winged stages paracercus is developed, subequal to cerci (unlike Baetisca/f2=g1). It can be a plesiomorphy or a
result of secondary development of imaginal paracercus from larval one. Caudalii (cerci and paracercus) of winged stages have no distinct segmentation, in female and in male subimago are very small (somewhat smaller than larval ones), in male imago they are several times longer, soft, with long irregular hairs (Gillies 1954: Fig.1-2).

Size. Small, fore wing length 27 mm.

Distribution. Eastern Hemisphere: Afrotropical, Oriental, Australian and Palaearctic Regions.

Nominal species in Prosopistoma/f1=g2: 

africanum Gillies 1954 [Prosopistoma]

alaini Bojkova & Soldán 2015 [Prosopistoma]  

amanzamnyama Barber-James 2010 [Prosopistoma]

annamense Soldán & Braasch 1984 [Prosopistoma]

boreus Peters 1967 [Prosopistoma]

carinatum Boonsoong & Sartori 2019 [Prosopistoma]

coorgum Balachandran & Ambalagan & Kannan & Dinakaran & Krishnan 2016 [Prosopistoma]

crassi Gillies 1954 [Prosopistoma]

deguernei Vayssière 1893 [Prosopistoma]

foliaceus Fourcroy 1785 [Binoculus] //

funanense Soldán & Braasch 1984 [Prosopistoma]

indicum Peters 1967[Prosopistoma]

lieftincki Peters 1967 [Prosopistoma]

mccaffertyi Barber-James 2010 [Prosopistoma]

ocellatum Shi & Tong 2013 [Prosopistoma]

olympus Sartori & Gattolliat 2003 [Prosopistoma]

orhanelicum Dalkiran 2009 [Prosopistoma]  

oronti Alouf 1977 [Prosopistoma]  

palawana Peters 1967 [Prosopistoma]

pearsonorum Campbell & Hubbard 1998 [Prosopistoma]

pennigerum Müller 1785 [Limulus] syn.subj. foliaceus [Binoculus]

phoenicum Alouf 1977 [Prosopistoma] syn.subj. oronti [Prosopistoma]

pisciforme Dumeril 1816 [Binoculus] syn.subj. foliaceus [Binoculus]

punctifrons Latreille 1833 [Prosopistoma] syn.subj. foliaceus [Binoculus]

sedlaceki Peters 1967 [Prosopistoma]

sinense Tong & Dudgeon 2000 [Prosopistoma]

someshwarensis Roopa & Selvakumar & Subramanian (in Roopa & Selvakumar & Subramanian & Sivaramakrishnan) [Prosopistoma]

trispinum Zhou & Zheng 2004 [Prosopistoma]

turcica Kazanci & Türkmen 2018 [Prosopistoma]

unicolor Zhou & Zheng 2004 [Prosopistoma]

variegatum Latreille 1833 [Prosopistoma]

wouterae Lieftinck 1932 [Prosopistoma]

Examined also:

sp. (Iraq)

sp. (Uganda)  ,

sp. (Tanzania) 

sp. (Zambia) lieftincki (Sri Lanka)

sp. (Thailand)

sp. (Sulawesi)