A key to the females of Fennoscandian Dryops Olivier (Coleoptera: Dryopidae)

A key to the females of Fennoscandian Dryops Olivier (Coleoptera: Dryopidae)

ANDERS N. NILSSON and MASSIMO OLMI

Introduction

The genus Dryops Olivier includes many mor- phologically very similar species and the species identification is often problematic. Reliable diag- nostic characters are only found in the genitalia, and useful identification keys to males are pro- vided by Olmi (1972) and Steffan (1979). The sep aration of the females has long been almost impos- sible, but the vaginal sclerites described by Olmi (1976 & 1978) provide good diagnostic characters, and these were also recently used by Wigllak

( 1986) in a key to the Polish spccies.

A survey of the Dryr-rps fauna of northern Swe- den (Nilsson 1984) discovered many erroneous re- cords, especially oI D. auriculatus (Fourcroy). It was concluded that only a single female from MArdsele in the Vasterbotten province belonged to this species. However, the study of a long series of specimens from this particular site (described by Nilsson 1986) by the junior _author has proven that this female in fact belongs to D. anglicanus Edwards. The previous misidentification was caused by the hitherto unknown intraspecific vari- ation in the number ofvaginal sclerites found in D.

anglicanus. This variation causes some females of D. anglicanus to key out as D. auiculatus in the key found in Olmi (1978: 13-14).

An additional record of D. anglicanus is from

Nilsson, A. N. & OImi, M.: A key to the females of ltnnoscandian DryoPs Olivier (Coleo ptera: Dryopidae). [Bestimningsnyckel till honorna av de fennoskandiska DryoPs-a erta (Coleoptera: Dryopidae).]- Ent. Tidskr. 108: 9!98. Ume6, Sweden 1987. ISSN ()(ll3-886x.

Observcd intraspecific variation in the number of vaginal sclerites (Plates) in Dryops anglicanus Edwaids has caused problems in the separation of this species from D. auiculatus (Fourcroy). A previous record from the Vdsterbolten province in northern Sweden is errone- ous and in fact iepresentin,9 D. angliconru. An illustrated key is provided for the identification of female Fennoscandian Dryops.

A. N. Nilsson, Dept- Animal Ecology, IJniversiry of Umed, 5-901 87 Umed, Sweden.

M. Olmi, Univeriitd degli studi dello Tuscia, Istituto di dilesa delle piante, Via S. Camillo De Lellis, l-01lA0 Viterbo, Italia.

ME: Holm, Stor-Sundsjcin, 9.vi.1985, leg. H.

Soderberg.

The purpose of this paper ^is to provide a key to the Fennoscandian Dryops females. The follow- ing key is based on that of Olmi ^(1978), but is partly revised and delimited to the species occur- ring in Fennoscandia and Balticum.

Diegnostic charrcters

In all Fennoscandian species the ovipositor is strongly sclerotized. Only in D. lutulentus (Er.), found in Balticum, is the ovipositor highly re- duced (Fig. 2 D). ^The shape of the sclerotized ovipositor is varying, but is not a useful diagnostic character.

The spermathecal duct is very long, thin and coiled in D. nitidulu: (Heer) (Fig. 2 C). In all other species it is markedly shortcr and thicker and at most only partly coiled.

In all species except the two ones mentioned above the vagina is provided with sclerites. At

most there are six vaginal sclerites and these are named in correspondence with their position ac- cording to Fig. 1 A-B. The different combinations

of vaginal sclerites found in each species are

shown in Tab. 1. The number of sclerites present

94 N. Nilsson & Massimo Olmi

EC._l 4-!. Dryops, vagqa arLd ovipocitor. - ^{A-B. D.} or rrarir Bo[ow- The vaginal scleritcs are: (Pr) prorimal, (LVPr) left vcnteroproximal, (RVPr) right vcntcroprorima!, (D) donat, (LDi) leltdistal and (RDi) rilht distal. - C- D. D. gniscrA (Er.). - ^{E-F. D. lurtulus (Et.).} - A,C, ^{E. I'.ateral aspect.} - ^{B, D, F. Ventral aspecl.}

Aggliggare och vagina hoc Dryops. I A-B visas de beteckningar som anvinds fdr dc otika Bkleritema i vaginan vilka

anvands vid artbestemningen.

Females of Fennoscandian Dryops ⁹⁵

Fig. 2 A-D. Dryops, yagir.a, ovipositor and spermathecal duct. -A-B. ^D. emesti Gozis. -C. ^{D. nitidulus (Heer).} -

D, D. lurukntus (Er.). - ^{A, C,} D. Lateral aspect. - ^{B. Ventral aspect.}

.liggliggare, vagina och sedesbeheUarens kanal hos tre arter zv Dryops.

96 Anders N. Nilsson & Massimo Olmi

A->+>'>

B>>

Fig. 3 A-E. Dryops, vagina and ovipositor. - ^{A-C. D.} atglicaaus Edw. - A-8. ^{Form without the vaginal D sclerite.}

- C. Form with the vaginal D sclerite. - ^{D-E, D.} auicuhtus (Fouro.). - A, D. Lateral aspect. - ^{B, C, E. Ventral}

aspect.

Acgltggare och vagilahos Dryops anglicanzs (A-C) och D. aL &latus (D-E).Hos den f6ra visas tvl olika former,

en med (C) resp en utan (A-B) sklerit D i vaginan,

is seemingly fixed in each species. Only in D.

anglicanus is the D sclerite only sometimes pre- sent, and all specimens cannot be separated from D. auriculatus on this character. A series of D.

anglicanus from JA: Revsund (leg. S. Persson, 30.vi.1986) show the same variation as found in the population from VB: Mirdsele. Of 9 females dissected from Revsund t has 4 and 2 each have 3, 2 or I teeth on the D sclerite respectively. The D sclerite is absent only in 2 of the 9 females from Revsund. ln Tab, I ^is also shown variation in the number of teeth on each sclerite.

In the Swedish material studied, the ovipositor is longer in D. anglicanus (1.80-1.88 mm) than in D. auriculans (1.72t-1.78 mm). Further has the D sclerite in D. auriculatus only 1-2 teeth, and in D.

anglicanus rp to 5 teeth. As these differences are not corroborated by the study of Central Euro- pean specimens (WigZlak, in litt.), they are not used in the key. Variation in these two species in Fennoscandia deserves further study.

For the study of the vaginal sclerites the vagina is carefully extruded together with the ovipositor.

Cleaning is either performed in a boiling solution of 10 7" potassium hydroxide for a few minutes or just with fine insect pins. The genitalia are then either stored in ^7O _"/o alcohol or mounted on slides.

Key

l. Ovipositor rudimentary (Fig. 2 D)

- i;;i;;ti;;;;;ilii ;;r;,# ^(h? yr,:"t;:..(:' )

2. Spermathecal duct long and slender, coiled up (Fig. 2 C). Vagina without sclerites (Fig. 2 C). ....

- ip;;;;i;;;;i a;t'i Jr,ii

"i,i iiiri, :'J'fl1fili;"d

partly coiled (Figs. I A, C, E, 2 A). Vagina with at least a single sclerite near the entry of the duct .. 3

3. ^Vagina with the Pr sclerite but without the LVPr and RVPr sclerites (Figs. 2 A-B, 3 A-E) ... ⁴

- Vagina with both the Pr and the VPr pair of scleri- tes(Fig. I A-F) ... 6

4. Vagina without additional sclerites (Fig. 2 A-B)

- ^{n;r;; ;;i; il; i;i} ;;i;;;.;'d;;; ;'?#fi'fio.:'o

times also with a D sclerite (Fig. ₃ A-E) ... ⁵ 5. Vagina without the D sclerite (Fig. 3 A-B) ...

... D. snglicanus Edw . (part\

- Vagina with the D sclerite present (Figs. 3 C-E,4)

... D. auiculatus (Fourcr.)& D. anglicanus (pafi) 6. Vagina without additional sclerites (Fig. 1E-F) ..

- ^{il;i;;.h. ;i; ;;;il;i} 6i;;i;;i.3 JfiYffi!:' ⁾

times also a D sclerite is present (Fi8. I A-D) ... ⁷

7. Vagina with the D sclerite present (Fig. I A-B).

Females of Fennoscandian Dryops 97

:ar-->>.u>>>.

4 >--;>

tL

.4

F,,';-i:..+*

Fig. 4. Dryops anglicanus Edw.. vagina in part from 4 females from VB: Mirdsele. ventral aspect.

Variation i vaginalskleriternas utseende hos 4 honor av D. unglicunus trinYB: Mirdsele.

Tab.

. Prcscnce of and numbcr of leeth on vaginal scler- ites in the Fennoscandian species of Dryops. For naming of sclerites see Fig. 1 A-B.

Vaginal sclerite

Species Pr ^LVPr/RVPr D ^LDi/RDi

D.lutulentus D. nitidulu\

D. ernesti D. anglicanus D. auriculatus D. luridus D. _Briseus D. similsris

,l-5 t-2

i

- ^Vagina without the D sclerite (Fig. I C-D). The Di sclerites are large with 3-7 teeth each (Fig.

C-D). ... ^{D. gnseas (Er.)}

Acknowledgement

We thank Dr W. W. Wigilak, Warsaw, for valu- able comments and information about specimens in his collection.

References

Nilsson. A. N. 198,1. Thc distribution of the aquatic beetlc families Elmidae and Dryopidae (Coleoptera) in northcrn Sweden. - ^Fauna Norrlandica. Umei, l98a(3): 1-13.

- 1986. Notes on the taxonomy and habitat of Rhantus fennicus (Coleoptera: Dytiscidae); with the first Swedish record. - ^Notulae Entomol. (t6 41-44.

Olmi, M. 1972. The palearctic species of the genus Dryops Olivier. - ^{Boll. Mus. Zool.} Univ. Torino

_

24 3-5

?4 24

;

3-7 l-2

>i>>>>>_>-> 4

\

,- --

/ - ("t'

10 {F=.L;>;>>-'-'

\ "B

---

98 Anders N. Ni/sson & Massimo Olmi 1972(5): 69-132

- ^1976. Colcoptera Dryopidac - Elminthidae. - ^Fauna d'Italia, Bologna. 12: 1-280.

- ^1978. Cuide per il riconoscimento delle species ani- mali delle acque inteme ltaliane. 2. Driopidi, Elmin- tidi (Coleoptera Dryopidae, Elminthidae). Verona (Consiglio nazionale delle ricerche).

Steffan, A. W. ^1979. 42. Familie: Dryopidae. - ^1n:

Freude , H., Hardc. K. W. & Lohse, G. A. (eds.).

Die Kiifer Mittele uropas. Band 6, pp. 261294. Kre- feld (Coecke & Evers).

Wigrtak, W. W. 1986. Chrzeszcze - Coleoptera. Par- nidae, Limniidae, Psephenidae. - Klucze do oznac- zania owad6w Polski XIX (48-49), ₆₇ pp.

Semmenfattning

Artbestiimning av honor av slaktel Dryops Olivier kan slkert goras endast pl basis av utseende hos inre genitalier. Inomartsvariation av antalet skle- riter i vagina hos D. anglicanus Edwards 96r att befintliga bestlmningsnycklar ej kan anviindas.

Ett tidigare publicerat fynd av D. auriculatus (Fourcroy) frin Viisterbotten avser egentligen D.

anglicanus, vilken iiven anmiils ftir Medelpad. En reviderad bestiimningsnyckel fdr honorna av de fennoskandiska D ry ^ops -artema presenteras.

Recension

Stari, ^P. 1987. Subjecr bibliography of aphid parasitoids (Hymenoptera: Aphidiidae) of rhe World 1758-1982.

Monographs to Applied Entomology. Band 25. Verlag Paul Parey, Hamburg und Berlin. 101 s. Hiiftad. ISBN 3- 490-11018-8. Pris 59 DM.

Bladlussteklarna (fam. Aphidiidae eller Braconi- dae, Aphidiinae) iir den enda stekelgruppen der

alla arter iir obligata parasitoider pl bladldss.

Cruppen, vilken omfattar en bra bit over 300 ar- ter, har virldsvid utbredning, men ar rikligast fo- retredd i tempererade och subtropiska omrAden. I Sverige kinner vi ca 110 arter. I minga liinder ut- gor bladltiss ett allvarligt ^problem fcir jordbruk och viixthusodling, antingen genom att reducera gr6dans tillvaxt eller genom att fungera som vek- torer for skadliga virus. I takt med stigande kost- nader fdr insekticider har biologisk bekiimpning med hjiilp av bl a bladlussteklar blivit allt mera in- tressant.

De senast publiccradc arbetena som innehiller ansenliga bibliografier <iver bladlussteklarna ut- kom ftir 20 (Mackauer & Starf 1967. Index of en- tomophagous Insects; Hym. Ichneumonoidea, World Aphidiidae. Le Frangois, Paris) respektive 17 ir ^{sedan (Starf 1970.} Biology of aphid parasi- tes. Junk, the Hague). Bida dessa bricker har dock sina begrdnsningar, bortsett fran att de nu bdrjar bli gamla. Den forra saknar en del viktiga referenser om biologi och biologisk bekiimpning, denandrasaknarcn heldel taxonomiskaarbeten.

FOreliggande bok, vilken ar en ren bibliografi, tacker hela bredden av titlar som berdr bladlus-

steklar pi clt eller annat satt. Den omfattar arbe- ten som er publiceradc mellan 1758 och 1982, dar- tillenstaka titlar fram t o m 1984. Referenserna iir

insorterade under tio olika rubriker: 'General tit- les','Biosystematics' (taxonomi, bestiimnings- nycklar, faunistik, viirddjurslistor, hyperparasit- anknytningar, fylogeni m m), 'Morphology and anatomy', 'Bionomics and life history' (levnads- siitt, reproduktion, spridning, hibernation m m), 'Host specificity' (parasiteringsstrategier, vard- djursspektra m m), 'Intraspecific categories and genetics','Parasitogenic effects' (relationer mel- lan bladlus och parasitoid, fysiologi, reproduktion och avkomma, m m), 'Impact on aphid popula- tions','Intraspecific relations' (hyperparasitoider, predatorer, nhringsvdvar, konkurrens m m) samt 'lntegrated pcst management'. Den sista avdel- ningen iir i sin tur uppdelad i sju underavdelning- ar. Grinserna mellan de olika kategorierna kiinns inte alltid naturliga, med fdljd att det ibland er sv&rt att veta vilken typ av titlar fdrfattaren sorte- rat under respektive rubrik. I mAnga fall ar dock ett arbete citerat under mer an en iimnesrubrik, varfcir problemet i praktiken inte ir si stort.

Sammanfattningsvis kan siigas att det her er en viilkommen bibliografi som kommer att vara den givna kiillan till referenser, inte bara fdr specialis- ter ^pa bladlussteklar, utan ocksi, och i iinnu h6gre grad, fdr dem som arbetar med biologisk bekiimp- ning av bladloss.

Ulf Grirdenfors