Dichotomous table for gallers on Carex

by Hans Roskam

1a On above-ground parts => 2

1b Roots with terminal swellings, 5–8 mm long, club-shaped; with almost colourless elliptical spores inside. C. limosa: Entorrhiza caricicola

2a In flowers or fruits => 17

2b On vegetative parts => 3

3a Leaves or stems with malformations caused by rusts or smuts => 14

3b Malformations caused by animals => 4

4a On leaves => 12

4b On buds, shoot tips or stems => 5

5a On stems or rhizomes => 7

5b On buds or shoots => 6

6a Lower parts of side shoots swollen, bud-like. C. praecox, ? echinata, ? flacca: Planetella sp.

6b Buds stunted, thickened; galls corniculate. C. elata, flacca, montana, pallescens, nigra, praecox, sylvatica. Planetella cornifex

7a Stem with various kinds of swellings => 9

7b Stem with lateral tufts of leaves or with depressions => 8

8a The stem with a laterally protruding severely stunted shoot with a tuft of severely disfigured, yellowish leaves, the covering sheaths are especially well developed and broadened. Carex sp., muricata, etc.: Livia crefeldensis

8b Stem and leaf sheath with weak depressions. Larvae often many per culm. Each depression contains a single orange-red larva. C. appropinquata, ericetorum, echinata, muricata, remota: Thurauia aquatica

8c With similar biology, may be conspecific with the previous midge. Thurauia uliginosa

= Also other gall midge larvae develop underneath the leaf sheaths of sedges without causing distinct galls:

a Antichiridium caricis, larvae red, on C. echinata

b Antichiridium striatum, larvae yellow, on C. pseudocyperus and Molinia caerulea

c Brachydiplosis caricum, on Carex spp.

d Sterrhaulus corneolus, larvae yellow-red, on Carex spp. According to Jaap (1918) this species also develops as an inquiline in galls of Planetella gallarum

9a Galls egg-shaped, rotund- to oblong-oval => 10

9b Axis of shoot thickened at base, onion-like. Sometimes the complete axis is transformed into a horn-like gall. C. ? bigelowii, flacca, montana, nigra, praecox: cf. Planetella cornifex

10a Galls one-chambered, usually not in dense clusters => 11

10b Shoot axis on rhizome already seriously stunted; often with only etiolated leaves above the ground. Stems or leaf sheaths with ± egg-shaped galls, which usually consist of several oblong-oval, flattened one-chambered parts. C. acuta, acutiformis, arenaria, davalliana, hirta, muricata, nigra, ? praecox: Planetella arenariae

10c Similar galls on C. flacca, nigra, praecox: Unidentified gall midge

11a Stem of shoot in ground, close to surface, with one-chambered, egg-shaped brown swelling, up to 2.5 mm long and 1.5 mm wide, grain-like. C. divulsa, echinata, nigra, praecox, pallescens, ? elata, filiformis: Planetella granifex

11b Similar, often acuminate galls, which are often only attached to the leaf at the tip and are ± distant from the further part of the leaf that bears them. Containing single larvae. Carex spp.: Planetella caricis

11c Similar galls, about 5 mm long. C. praecox: Planetella sp.

11d From C-Eu has been described from C. praecox: Planetella caricis var. baudysi

11e Acuminate galls on culms close to the ground; egg-shaped, about 2 mm long and 1.2 mm wide, one-chambered. C. echinata: Planetella kneuckeri

11f Stem of shoot, also leaves, usually close to the ground, with oblong, glabrous, ± glossy brown, terminally rounded galls, only connected with their middle part to the basal leaf part, narrowed at both ends. Containing a single white larva. Carex spp.: Planetella gallarum

11g Similar galls on C. vesicaria. Larvae white: Planetella tarda

11h Similar galls on C. pseudocyperus: Unidentified gall midge

12a Galls usually less than 5 mm, one-chambered => 13

12b At base where leaves come close to one another, are complexes of several whitish or brownish galls, 5–8 mm long and 2–3 mm thick, acuminate, with thin leathery walls. Containing a single larva. C. ? hirta, pilosa, rostrata, vesicaria, and probably other sedges. Planetella fischeri

12c Similar galls at base of a leaf at lowest node. C. acuta, nigra, praecox:
Planetella rosenhaueri

12d Similar galls on C. davalliana, filiformis, vesicaria: Planetella sp.

= On C. davalliana: Planetella billoti

12e Single- or multi-chambered gall, up to 10 mm long and 5 mm broad. C. appropinquata, acutiformis: Planetella sp.

12f Oblong swellings at leaf base. C. nigra, praecox, pallescens, elata, ? filiformis: Planetella sp.

12g Similar galls on C. divulsa, pallescens: Planetella frireni

13a Subterranean leaf sheaths with oblong-oval single-chambered swellings, up to 4 mm long, about 1 mm broad, thick-walled, dark-brown. Containing a single orange-yellow larva. C. flacca: Planetella sp.

13b Small blister-like swellings of leaf base; often many on several shortened leaf blades. C. acuta, ? hostiana, elata, etc.: Planetella tuberifica

13c Leaves similarly swollen at base, containing many slender spindle-shaped single galls. Each chamber contains a single larva. C. acutiformis, pseudocyperus: Planetella tumorifica

13d Rotund-oval galls, about 3 x 2 mm on subterranean leaf parts. C. divulsa, praecox: Planetella subterranea

14a Expanded stripes on leaves, caused by smut fungi => 15

14b Patches in disfigured stalks of inflorescence; midrib and also culm of diseased plants ± shortened. Spores in balls, not enveloped by sterile cells. Carex spp.: Moreaua aterrima

15a Spores clustered in balls, enveloped by sterile cells => 16

15b Spores single. Smut sori in long, parallel stripes. C. brunnescens, canescens, glareosa, lachenalii, macloviana, etc.: Orphanomyces arcticus

16a Stripes of smut on leaves of various length. Spores 1–2 (4) often without gaps, enveloped by sterile auxiliary cells. Carex spp.: Urocystis fischeri

16b Stripes similar. Spores with 1–6, mainly 3, ± completely enveloped by sterile auxiliary cells. C. montana: Urocystis littoralis

17a Malformations on flowers or fruits, caused by fungi => 22

17b Galls on flower parts caused by gall mites or gall midges => 18

18a Malformations on ovaries or fruits caused by gall midge larvae => 19

18b Utricles transformed into very long, thickened galls. C. misera, nigra, praecox: Phytoptus caricis

19a Galls less than 5 mm long => 21

19b Galls about 5–9 (12) mm long => 20

20a Ovary transformed into an acuminated, cylindrical, usually pale green gall, 5–10 (12) mm long. Larva orange. Especially on sedges of the subgenus Vignea, such as C. brizoides, caryophyllea, disticha, divulsa, vulpina, pairaei, etc.: Wachtliella caricis

20b Galls similar, more club-shaped. Larvae pink-coloured. C. arenaria: Oligotrophus loewianus

20c Utricles strongly enlarged, containing a single lemon-yellow larva. C. cuprina: Dasineura inflata

= The galls cannot be differentiated externally form those of Wachtliella caricis. A difference is that the larvae of inflata are lemon yellow, while those of caricis are orange

21a Ovary, or fruit inflated into an egg-shaped gall, up to 3 mm long. Containing a single orange-coloured larva. C. elata: Unidentified gall midge

21b Similar gall, described in no more detail, on many other sedges. Unidentified gall midge

21c Utricles thickened, containing a single orange-red larva. C. acutiformis:
Dasineura koesterbecki

21d Utricles disfigured, containing a single orange-red larva. C. paniculata:
Dasineura minungula

22a On the first slightly enlarged ovaries, which are soon destroyed, develop considerable smut bodies, protruding conspicuously from the inflorescence; these are initially compact and enclosed by a white envelope, releasing their solitary, mutually ± firmly clotted spores rather late => 24

22b Malformations on various flower parts or on ovaries with lightly dusting of sori => 23

23a Ovaries swollen, soon filled with a dark olive-brown to blackish mass of single spores, pervaded by sterile hyphae. Spores lightly dusting or crumbling, leaving the sterile hyphae as characteristic, soon ± fraying bundle. C. riparia and many other Carex species: Farysia thuemenii

23b Black-brown spore balls in various disfigured flower parts; on more rarely infected female florets often in the abnormally elongated perigyne, often only in the ovary, on male florets predominantly in the anthers. Carex spp.: Moreaua aterrima

24a Spore wall glabrous or with small papillae => 27

24b Spore surface with distinct warts => 25

25a On C. canescens, nigra, rostrata => 26

25b On many sedges of the sect. vesicariae, hirtae and hybrids: Anthracoidea subinclusa

26a On C. rostrata, pilulifera, rotundata and close relatives: Anthracoidea inclusa

= On C. canescens, with glabrous spores, lives the closely related Anthracoidea karii

26b On Carex sect. Acutae: Anthracoidea echinospora

26c On C. canescens and relatives: Cintractia fischeri

= On C. pilulifera, the ovary smut Cintractia caricis-oederi has been described.

27a On many sedges species complexes of ovary smuts occur. Spores irregular, ± edged, 15–26 x 12–22 µm. Wall dark brown, with very many fine warts. Nominate form on C. pilulifera: Anthracoidea caricis

27b Many fungi are ± host-specific and partially morphologically distinct:

a On C. alba. Spores ± angular, with many fine papillae, 19–27 x 12–21 µm. Also recorded from C. digitata, ornithopoda, sempervirens: Anthracoidea caricis-albae

b On C. arenaria. Spores dispersing early, rotund to elliptical, ± flattened, 13–18 x 12–16 µm.: Anthracoidea arenariae

c On C. brizoides, cespitosa, divulsa, echinata, muricata, leersii, pairae and relatives Spores irregular rotund, appearing almost glabrous at maturity, 13–20 x 12–17 µm.: Cintractia leioderma

d On C. brunnescens and hybrids. Spores 15–22 x 10–16 µm, ± irregular rotund-elliptical, with yellowish-brown glabrous or minutely punctated membrane; therefore clearly different from Anthracoidea fischeri: Anthracoidea karii

e On C. chordorrhiza. Spores rotund to elliptical, 15–22 x 11–19 µm; wall dark-brown, with, only slightly protruding, about equal warts; forms transition to warty-spored species. Usually all spikes with many or all ovaries diseased: Anthracoidea aspera

f On C. digitata and relatives. Spores ± elliptical, very polymorphic, 18–27 x 13–22 µm. Wall brown, with many densely positioned, not protruding, rotund or ± elongate small warts. Smut grains rotund, 2–5 mm across; usually solitary to several in the fruiting spikes, sometimes dropping as a whole: Anthracoidea irregularis

g On C. dioica and hybrids. Spores rotund-elliptical, ± angular, 18–26 x 16–22 µm. Wall dark brown, with densely arranged inclusions, making the membrane almost non-transparent. Close to nominate form: Anthracoidea turfosa

= Also found on C. dioica, distinguished by its smaller spores is Anthracoidea caricis-dioicae

h On C. ferruginea: Anthracoidea caricis

i On C. flacca, buxbaumii. Smut grains relatively soft and soon dusty; spores rotund or elliptical, sometimes slightly angular, 16–26 x 14–22 µm.: Anthracoidea pratensis

k On C. glareosa. Spores 15–21 x 13–19 µm; membrane very thick, up to 2.6 µm, with densely arranged ± coalescing, minute papillae: Cintractia glareosa

l On C. hirta. Spores rotund- to oblong-oval, usually strongly flattened and irregular angular, 16–26 x 13–21 µm; wall dark-brown, up to 2 µm thick, almost glabrous: Cintractia angulata

m On C. limosa and relatives. Spores rotund to elliptical, often flattened, 17–26 x 14–24 µm; wall almost glabrous. Smut grains 2–5 mm across; envelope soon rupturing; spores crumbling: Anthracoidea limosa

o On C. panicea and relatives. Spores rotund- to oblong-oval, very irregularly shaped and rimmed, densely finely punctate, 18–20 x 13–17 µm. Other hosts are C. echinata, nigra, praecox, pilulifera: Cintractia baccata

mod 20.xi.2019