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(fragment of the Key
to freshwater invertebrates
of Russia and adjacent lands)
1(14). 1(14). Legs 6-segmented, normally with 2 claws (only in Haliplidae with one claw) . . . suborder Adephaga
2(3). Antennae 3-segmented; thoracic and abdominal tergites with flat lateral lobes; spiracles on the 8th segment shifted towards the dorsal side; urogomphs 1-segmented, articulated . . . Amphizoidae
See key to families by adults.
3(2). Antennae 4-segmented; when thoracic and abdominal tergites with flat lobes, spiracles of abdominal segment 8 are situated laterally.
4(5). Terrestrial species, frequently inhabditing near water edge; abdomen with well developed segment 8 (sometimes 8th and 9th segments bear a large glandular disc and the segment 10 forms hypopod; on segments 1-8 pair of spiracles is situated); labium with ligula . . . Carabidae (Table 37: 1)
Trachypachidae
See key to families by adults.
5(4). Aquatic species, coming on land only to pupate; if abdominal segment 10 developed as hypopod, there are tracheal gills.
6(7). Abdominal apex with 2 pairs of strong hooks on reduced segment 10; without preapical spiracless behind segment 3; abdomen always with a pair of long lateral gills on each of the 1st to 8th segments and the 9th segment with 2 pairs of gills . . . Gyrinidae - Whirligig beetles (Table 61) (p. ???)
Forms crawling on the bottom.
7(6). Apex of abdomen without 2 pairs of strong preapical hooks; abdominal segments without lateral gills or sometimes with ventral gills.
8(9). Abdomen with 10 segments (10th segment sometimes very small) and legs with 1 simple claw, always one pair of urogomphoid processes, sometimes strongly reduced; thoracic and abdominal segments 1-9 with more or less elongated gills in mature larvae (with 1 or 2 pairs on each segment); mesothoracic and 1-7 abdominal spiracles only in larvae of the 3rd and last instars; mandibles wide and short with canaliculus and opening in front of the apex . . . Haliplidae - Crawling water beetles (Table 51-54) (p. ???)
Forms crawling over aquatic plants.
9(8). Abdomen with 8-9 segments and legs with 2 claws.
10(11). Abdomen with 7 distinct segments, segments 8 and 9 are very small with long narrow urogomphi; small reduced spiracles only on mesothorax and abdominal segments 1-7 (only in larvae of the last instar), thoracic and 1-3 abdominal sternites with gill filaments; mandibles without mola, internal groove or buccal opening in front of apex . . . Hygrobiidae (Table 37: 11; 38: 3-5)
Forms crawling on the bottom; see key to families by adults.
11(10). Abdomen without tracheal gills on underside, segment 8 not shorter than or slightly shorter than segment 7.
12(13). Mandibles narrow, without mid process - retinaculum, with canaliculus opening inside before apex; abdominal segments 1-7 different in size and shape; abdominal segment 8 not extended above the 9th into straight process, bearing spiracles; urogomphi normally long and thin, formed of 2 segments (the 2nd very thin and sometimes rudimentary up to a small knob on underside, when they are short or absent, the body is large (mature larvae not shorter than 15 mm); legs swimming . . . Dytiscidae - Predaceous diving beetles (Table ???) (p. ???)
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13(12). Mandibles thick and wide, with pronounced mid process - retinaculum, with internal groove or buccal openining before apex; abdominal segments 1-7 similar; segment 8 is stretched above segment 9 into a sraight root bearing spiracles, or segment 8 is simply hanging in the shape of widely rounded apex above segment 9 (Phreatodytinae); urogomphi are short non-segmented and sometimes not developed (Phreatodytinae); legs burrowing; body small, not more than 8 mm . . . Noteridae - Noterids (Table 56) (p. ???)
Live near roots and other parts of aquatic or sunken plants
14(1). Legs as maximum with 5 segments and one claw, sometimes segments reduced in size and number . . . suborders Myxophaga and Polyphaga
15(20). Body soft, eruciform or apodal, strongly membranized without pronounced processes and with 8-10-segmented abdomen, without legs or on tergites of abdomen spiracles are transformed into hooks.
16(17). Legs small, but distinctly developed; abdomen with 8 segments, with 7 pairs of normally small spiracles, and 8th pair of spiracular chambers transformed into dorsal hooks . . . Chrysomelidae - Leaf beetles (Polyphaga), subfamily Donaciinae (Table ???) (p. ???)
On and inside angiosperms and horsetails, also near roots.
17(16). Legs not developed; abdomen with 8 developed and 2 last reduced segmemnts with 9 pairs of small spiracles: 1 on mesothorax and 8 on the first abdominal segments; sometimes 6 pairs of spiracles are transformed into dorsal hooks or abdomen with transversely truncate apex, bearing a pair of preapical spiracles on soft processes
18(19). ??? . . . Brentidae (syn. Apionidae) (Polyphaga) (Table ???) (p. ???)
???
19(18). ??? . . . Curculionidae - Weevils (Polyphaga) (Table ????) (p. ???)
??? (larvae of subfamilies Molytinae, Erirhinae and Ceutorhynchinae), and ??? larvae Phytobius Schцnher, 1833 and Eubrichius Thomson, 1859 (subfam. Ceutorhynchynae) ??? (Myriophyllum).
20(15). Body with sclerotozed sites and with processes.
21(22). Head inflated with eyes remote from each other; labrum distinct; abdomen with 10 segments, segment 9 with a pair of 2-segmented urogomphi, segment 10 with a pair of thick bent anal gill or without those; spiracles on mesothorax and abdominal segments 1-8 are ringed . . . Hydraenidae - Hydraenids (Polyphaga) (Table ???) (p. ???)
Inhabit on plant remains in water or near water bodies in mud, sand and on the lower surface of stones, feed on algae.
22(21). Combination of characters is different.
23(24). Maxillae unilobed (with mala) or less frequently with rudiments of galea and lacinia and 10-segmented abdomen with articulate urogomphi, segment 10 as a rule elongate, cylindrical; ligula uni- or bilobed . . . Staphylinidae - Rove beetles (Polyphaga) (Table 37: 3, 4)
Larvae actively moving on earth (nonaquatic); see key to families by adults.
24(23). Maxillae bilobed, 8-9-segmented abdomen with articulate urogomphi or, when maxillae are unilobed (i.e. with mala), 9-segmented abdomen without or with very short non-articulate urogomphi (segment 10 modified into hypopod, bent ventrally); and only in species of Torridincolidae (Myxophaga) urogomphi may be long and articulate; lobes of ligula not developed.
25(40). Abdomen with 8 or 9 distinct segments, often terminated by urogomphi (absent in Spercheidae).
26(27). Body oval, flattened, strongly narrowed backwards; antennae 2-segmented; 1-8 segments of abdomen with articulate spiracular gills; abdomen with long articulate urogomphi . . . Torridincolidae (Myxophaga) (Table 37: 7-10)
See key to families by adults.
27(26). Combination of characters is different (when body is similar, abdomen without urogompi: antennae not less than 3-segmented; spiracular gills, if developed, not articulate.
28(33). Abdomen with 9 distinct segments: antennae of normal structure.
29(30). Body strongly dilated in the middle, flattened, abruptly narrowed backwards; head inflated with convex anterior edge (without long hairs), with developed gula, attaining epicranial base; spiracles reduced; abdomen without urogomphi . . . Spercheidae (Polyphaga) (p. ???)
In the strand zone and in shallow waters of lentic and slowly running water bodies. See key to families by adults.
30(29). Body elongate; abdomen with biforous spiracles (not annular as in Hydraenidae) and urogomphi; head flattened, with emarginate anterior edge between frontal sutures bearing long hairs, without gula reaching epicranial base; labium without ligula. Larvae amphibiotic or even terrestrial, inhabiting on banks of water bodies.
31(32). Urogomphi long and 2-segmented; legs well-developed . . . Helophoridae (Polyphaga) (Table ???) (p. ???)
As a rule predators; beneath and inside strand litter.
32(31). Urogomphi short cylindrical; legs short, reduced . . . Georissidae (Polyphaga) (Table ???) (p. ???)
Feed on algae in sand and mud; see key to families by adults.
33(28). Abdomen with 8 distinct segments; sometimes with long multisegmented antennae.
34(39). Antennae short, with few segments; abdominal segment 9 without anal gills and separated labrum; urogmophi 1-2-segmented.
35(36). The last abdominal segment with simple apex, without urogomphi; other abdominal segments with long flexible and smooth filamentous processes (gills), normally with one pair on each of the 1-7 segments, sometimes with greater or less number, last segment with unpaired process . . . Hydrophilidae - Water scavenger beetles (Polyphaga), subfamily Berosinae (Table ???) (p. ???)
Predators in lentic water bodies.
36(35). Last abdominal segment with short urogomphi; other abdominal segment without or with short branched outgrowths (gills)
37(38). Thoracic tergites complete and almost homonomous; head with small, but distinct gula; mandibles with sharp projection at the base (pseudogula) and with 2 long bent denticles; labium without ligula . . . Hydrochinae (Polyphaga) (Table ???) (p. ???)
Predators in lentic and slowly running waters.
38(37). Only prothoracic tergite complete, with developed ligula or without it . . . Hydrophilidae - Water scavanger beetles (Polyphaga), part (Table ???) (p. ???)
Predators in different aquatic and humid habitats.
39(34). Antennae very long and multisegmented; labrum pronounced; abdominal segment 9 with 5 indrawing anal gills, without developed urogomphi . . . Scirtidae - Marsh beetles (syn. Helodidae) (Polyphaga) (Table ???) (p. ???)
Forms feeding on aquatic fungi and algae.
40(25). Abdomen with 9 distinct segments and always without urogomphi (at least articulate).
41(42). Head without separated labrum; clypeus with medial tooth; mandibles long, symmetrical, with internal canaliculus; maxillae with distinct galea and licinia; body with wide flattened sclerites; head relatively retracted into prothoracic segment; abdomen with fluorescent organs . . . Lampyridae - Fireflies (Polyphaga) (Table 37: 5, 6)
Larvae normally terrestrial, sometimes inhabiting near water bodies or in water; see key to families by adults.
42(41). Head with distinct labrum; mandibles without internal canaliculus; body without fluorescent organ; combination of other characters is different.
43(48). Abdominal segment 9 of different shape, but always with operculum covering anal area, with two arranged externally anal stylets (at least in the last instars).
44(45). Abdominal segment 9 nearly conical and without indrawn anal gills; when head with eyes, there are 6 stemmata on each side, sometimes partly shifted on underside . . . Dryopidae (Polyphaga) (Table ???) (p. ???)
Normally in plant remains or in soil rich in organic substances near water bodies or in water; phytophagous.
45(44). Combination of characters is different; but abdominal segment 9 with retractile anal gills.
46(47). Head with 6 well developmed stemmata on each side, a part of which is shifted to underside . . . Elmidae (Polyphaga) (Table ???) (p. ???)
Phytophagous inhabitants of lotic water bodies, frequently beneath stones of mountain rivers and streams.
47(46). Head with only 5 stemmata brought closely together on each side, but never situated on underside . . . Limnichidae - Minute marsh-loving beetles (Polyphaga) (Table ???) (p. ???)
Known as phytophagous inhabitants of water bodies, also beneath stones in rivers and streams.
48(43). Structure of the 9th abdominal segment different.
49(50). Body rather elongate and cylindrical; sensorium of antennomere 2 of nearly equal length with antennomere 3; tergite IX not infrequently with relatively elongated apex . . . Ptilodactylidae (Table ????)
See key to families by adults.
50(49). Body oval or moderately elongate, often flattened, but never cylindrical; sensorium of antennomere 2, if developed, always much smaller
51(52). Antennae very short; stemmata very large; mandibles with developed pseudomola; body nearly vermicular, without segments of cilia or thickened setae, fringing sides or posterior margins, but with simple hairs nearly evenly dispersed over dorsum . . . Heteroceridae - Variegated mud-loving beetles (Table ???) (p. ???)
Inhabit mud, soil and send near water edge, where they build their tunnels; feed on algae and other planctonic forms.
52(51). Antennae very long (fam. Psephenidae) or moderately long (suborder Myxophaga); stemmata of normal sizes or assembled in one "eye" on each side; body nonvermicular, sides or posterior margins of segments are fringed by cilia or thickened setae.
53(54). Head retractile and normally not visible from above, stemmata assembled in one "eye" on each side, mandibles without mola; the majority of segments with lateral lobe-shaped outgrowths bearing cilia and giving the body disc-shaped appearance with hemicircular anterior edge of prothorax; but abdominal segment 8 without outgrowths and the 9th segment moderately developed; ventral gills on the ventral side pinnate . . . Psephenidae (Polyphaga) (Table ???) (p. ???)
Feed on algae; normally above or beneath sunken stones; See key to families by adults.
54(53). Head at least partly visible from above, normally triangular with 4-5 stemmata on each side brought together, mandibles with developed mala; abdominal segment 9 moderately reduced; ventral gills nonpinnate . . . suborder Myxophaga
55(56). Body only with 3 pairs of gills in the form of simple lobes on prothorax, abdominal segments 1 and 8; head with 5 stemmata on each side . . . Hydroscaphidae (Table ????)
See key to families by adults.
56(55). Abdomen with lateral gills on 1st to 8th abdominal segments; head with 4 stemmata on each side . . . Microsporidae (Table 37: 2)
See key to families by adults.