Quoderno di Srudie Notizie di Storio Nqturole dello Romogno
17suppl.:l7-24, giugno2003 tssN1123-6787
Quad.StudiNat.Romagna,
Fernando
Pederzani
HYDATICUS SATOI DHOFARENSIS N. SSP.FROM OMAN
(InsectaColeoptera
Dytiscidae)
Riassunto
[Hydaticus satoi dhofarensis n. ssp. dell'Omanf
Si descrive vrraÍazza geografica di Hydaticus satoiWewalka, 1975, cui si attribuisce lo status
di sottospecie e la denominazrone dt Hydaticus satoi dhofarensls n. ssp. Numerosi esemplari
del nuovo taxon sono stati raccolti nella regione di Dhofar (Oman) dal Dr. Marco Dellacasa del
Museo di Storia naturale e del Territorio dell'Università di Pisa. Alcuni esemplari della medesima provenienza efano stati segnalati in passato (BnaNcuccr, 1980) come Hydaticus satoí
Wewalka, così identificati per le caratteristichedell'edeago. La disponibilità di materiale più
abbondanteha consentito di evidenziare alcuni costanti caratteri distintivi, come le dimensioni
maggiori, il corpo più largo e dilatato dopo la metà e il disegno giallo elitrale limitato per lo più
ad un'unica, sottile fascia laterale. La costanza di questi caratteri e la notevole distanza che
separa la popolazione del Dhofar dal rimanente areale di H.satoi, assente da Iran e Pakistan
meridionale, suggeriscono trattarsi di una forma endemica, evolutasi a causa dell'isolamento
geografico. La sottospecie è confrontata con la forma tipica e con alcune specie vicine.
Abstract
Hydatícus satoi dhofarensrs n. ssp. is described from the Dhofar region, Oman, and compared
with the nominal form and some allied species.
Key words: Hydatícus satoi dhofarensls, Dhofaq Oman, Dytiscidae.
Introduction
Dr. Marco Dellacasa,of the Natural History Museum, Pisa University, kindly
submitteda collectionof 35 waterbeetlessampledduring a trip to Oman,Dhofar
region,in October2002.
The Dhofar region is subdividedinto 9 provinces(wilayats). Its climate is
dramaticallydifferentto the rest of Omandue to the effectsof the monsoonrains
(khareef)which arrive during the summermonths,creatinghumidity and moderate temperaturesof around 300C. As a consequence,
the areabecomeslush and
green,with waterfallsand rivers feedingthe surroundingpastures.The mountain
ridge,which receivesthe mostrain, stretchesfor 400 km from eastto west.Durins
t7
the khareef, springs gush forth and provide plentiful water suppliesfor much of
the rest ofthe year. The fresh greeneryis ideal for cattle graziÍtg,and livestock
rearingis an importantoccupationin the arear.
Climatesupportsthe survivalofplants andanimalsforming an uniqueecosystem,
a relict of the time when Arabia was not so arid and desertas it is today. The
justify the greatnaturalistic
uniqueecosystemandthe high numberof endemisms
interestof the Dhofarregion.
The small collection of water beetlesreceived for identification comprises4
specimensof Gyrinidae,23 Dytiscidaeand 3 Hydrophilidae.The most abundant
speciesis a distinctive,possiblyendemicHydaticusLeach, I 8 17, dealtwith here
below; the othersare widely distributedspecies.BnaNcucct(1980) reported4
exx.of Hydaticussatoi Wewalka,I9l5 fromOman,Dhofarregion,October1979,
leg. Larsen,and noticedtheir reducedyellow elytral pattern.The assignmentto
Hydaticussatoi was due to the shapeof penis.Sincemore specimenswere made
availablefor studyby Dellacasa'scollection,it becamepossibleto outline a few
constantdifferencesbetweenthe type form of Hydaticus satoi and the taxon from
Dhofar.No doubtsthe latter is closeto the former and possiblyderivesfrom an
original stock of that species,cut off by withering climate. Actually Hydaticus
satoiis not reportedfrom both southernPakistanand Iran, so thereis a wide gap
of arid countriesbetweenthe distributionareaof Hydaticussatoi f . typ. (India and
eastward)and the Dhofar region of Oman. Whether the endemic taxon is a
geographicalrace of H. satoi or has developedinto a different species,it is an
openquestion.Howevera reasonableassumptionis to assignit subspecificstatus.
Hydaticus satoí dhofurensl's n. ssp.
Type material
Hydaticussatoi dhofarensisn. ssp. (23 exx.)
17o08,64
N - 54'10,85'E,m 130,5.IX.2002";4
6 66 and8 Q Q:"Ain Sanahawq,
"Wadi
- 54"36,56'E,m 350, 10.IX.2002";1
Hinna,
17o03,20'N
66 and2 ??:
"Wadi Darbat,basecascata
fbelow waterfall],Hg light, 11.IX.2002";I é and
Q:
"Jabal
I Q:
Samhan,E of Hyoor,17"07,88'N- 54'43,99'E,m 1350,14.IX.2002".
E, m
17o08,64
N - 54o10,85'
Holotype:a malespecimenlabelled"Ain Sanahawq,
130,5.IX.2002"depositedin the NaturalHistory Museumof Pisa(Museodi Storia naturalee del Territoriodell'Universitàdi Pisa).The remaining22 specimens
areparatlpes.They aredepositedin theNatural History Museumof Pisa,in author's
collection,in coll. SaverioRocchi(Florence)andcoll. GùntherWewalka(Vienna).
Referencematerial
Hydaticussatoi satoi Wewalka, 1975(30 exx.)
' This paragraphwas downloadedfrom an ofhcial site of Dhofar govemment on the web
18
Figs. 1-4 - Median lobe ofthe aedeagus(a: side view, b: dorsal view): l. Hydaticus satoi dhofarensis n. ssp.
[Oman]; 2. Hydaticus satol satol Wewalka [Myanmar]; 3. Hydaticus vitîatus vittatus (Fabicius) [India, Assam];
4. Hydaticus víttatus vittatus (Fabricius) [Japan, Okinawa].
r9
1 j: "Bhutan, Dorjee Kandu, Dorjula 3100 m, 2.IX.1976.det. M.BranatccT";2
"Nat. Hist. MuseumBaselBhutanExpeditionl972,Paro2300m. 28.IV.|?1.I972
i:
det. Wewalka"; | 6'. "Nepal m 2000 NagarcotVII.1995 leg. Ammosov"; 1 i:
"IndiaAssamShillongKhasi Hills leg. Sircar1968";3
63 and3 ??: é South
India, Madras State,Coimbatore1400 ft. XI.l974leg. T.R.S.Nathan"; Mysore
State4 Q8: "SouthIndia CoorgDist. Mercara4000 ft.V.l9l3leg. T.R.S.Nathan";
1 é and I t: "South India Mysore State,ShimogaDist. Agumbe Chat 2000 ft.
V.l974leg. T.R.S.Nathan"; I Q: "South India, Kerala State,Trivandrum Dist.
PoonMudi Range3000ft. V.19721eg.
T.R.S.Nathan";1 é and 1 !: "N. Myanmar,
Putao 500 m 23.YII.I998 leg. S. Murzin & V. Siniaev"; | $: "Mus. Pragense
Tenasserim[Myanmar] col. Helfer, det. Wewalka"; | 6 and I Q: "North Thailand,
Mae Taman,50 Km NW ChiangMai, 25.VI - 4.VII.1998, leg. E. Kuèera"; I i
and I t: "Laos north, 15 Km NW LouangNamtha21"07.5'N - 101'21.0'E, alt.
750+100ml3-24.Y.1997E. Jendek& O. Sau5aleg|';2 $$ and3 ??: "Laos
north 20 Km NW LouangNamtha21"09.2'N - 101'18.7'E alt.900+100m 5Il.V.l99l E. Jendek& O. Sau5aleg.,det.S. Rocchi".
Hydaticus vittatus vittatus (Fabricius, 1775)
Only figured specimensare listed.
I i : "India, Assam,6 mi N of Tinsukia,9.IV.l 944 DF.Hardy,det.Wewalka flength
12.53mml (Figs.3 and 5);
1 i: "Japan,Okinawa, IshigakijimaIs., 15-20.XIL1987,leg. Y. & T. Abe, det.
T.Abe" fiength13.14mm] (Fig. a).
Description
The following descriptionpoints out principally the differencesbetween the
subspeciesand the nominal form of Hydaticus satoi Wewalka, I 975.
Size
Hydaticus satoi dhofarenslsn. ssp.
Length I 3.4 - 15.10 mm; meanlength 14.I 9 mm (o : 0.43),meanratio of width to
length0.567(o: 0.0077).
The holotypeis 14.55mm in lengthand 8.25mm in width, ratio of width to length
0.567.
Hydaticus satoi satoi Wewalka, 1975
Literaturedata:length 12 - 14 mm (Wnwerre,1975).
Referencematerial:length 12.37- 13.95mm, meanlength 13.35mm (o:0.462);
meanratio of width to length0.552(o : 0.0084).
Shape
The subspeciesdhofarensrsis broader and less tapering in front and behind than
the nominal form. It is broadestbehind the middle. The ratio of width to length is
higher in dhofarensls(broaderbody), usually higher than 0.56, and is lower than
0.56 in the nominal form, as a rule.
20
More details on size and shapeare given in the following table.
,
body length (mm)
:
s;i,.àl;f;;,,;iÀi,l;3
.d h o J a r e n(s' i s iiî 1'1ji:.,4
1 3 . 4 iii+.S5
1 4 . 5 s jij.ee-i.40'
i 1 3 . 9 91 . 4 0
t1t
;i.udt;fb;;;ii;i;
ò
n u J u r e n ùyQ
-*
i:ti
tz
i
s d f f.i , e n t i ; i s G l i,jj
,
j^e5 ) . r u jI i4.ia
r 4 . J U i .f6
iiir r . o ) i rii.iO
i.ió
.. r 1 . 4 - i r 5 . r o i: t c t s i . q3
,
ratio of *iatt to terrgrt
i.jjl
i . s 5 3 i.sd: i.saa ,ooir
_,.j60 i . S g r i : 5 6 6 i . 0 ò S ó
.0064
i . 5 6 9 ji.Ooo+
i . 5 7 7 i.SoO
jr . 5 6'0 i:sii-"
.
' '
.553 ;.583 ,,.5òj '.iOij
Table1.Body lengthandratio of width to lengthmeasuredin 30 exx. of Hydaticus
satoi satoi and23 exx. of Hydaticus satoi dhofarensisn. ssp.
The table gives the results of measurementsand some statisticalarrangements.A
self explaining representationof the differencesin length and ratio of width to
length betweensatoi f. typ. and ssp.dhofarenszsis shown in fig. 8. In spite of a
moderateoverlapping,the two subspeciesform different setsof points.
Colour pattern
upper sideblackwith yellow pattern.Headyellow in front andblack behind,as in
-l
:l
1
Figs. 5-7 - Colour pattem of the dorsal side: 5. Hydaticus yiîîotus vitfaîus (Fabricius) [India, Assam];
Hydaticus saîoi saîoi Wewalka [Myanmar]; 7 Hydaticus satoi dhofarensisn. ssp. [Oman].
2l
most speciesof fhe vittatusgroup.Pronotumwidely yellow at sidesand black at
the middle. The border line betweenblack and yellow is slightly angulateat the
middle (Fig. 7) as in the type form (Fig. 6).
The yellow bandsof elytra are narrowerand shorterthan in H. satoi satoi. The
outerband attainsthe margin at baseand is submarginalbehind,extendingshort
beyondthe middle of the elytral length as a rule, exceptfor a few specimens,in
which the outerbandapproaches
thepreapicalyellow spot.The outerbandis very
narrowin melanicspecimens,but nevermissing.The inner (discal)bandis either
absentor reducedto a short and narrow sub-basalstripe, not connectedto the
outerband.Preapicalyellow spotsalwaysdetectable,also in melanicspecimens.
Undersidedark brown with yellow prosternalprocess;anteriorlegsandmesofemurs
yellow; intermediatetibiaeandtarsilight brown,posteriorlegsdarkbrown; setose
fields of metatarsiwith long black setae,paler at apex; palpi and basal half of
antennaeyellow.
Puncturation
The dorsalsurfaceis coveredby a denseandminutepuncturationwith interspersed
larger punctures,principally at the base of elytra. The submarginalrows of
puncturesof pronotumandthe elytralrowsaswell asthe sculptureof theunderside
do not presentdifferentialcharacters.
Sexualcharacters
Male. The medianlobesof the aedeagusinsatoi f. typ. and ssp.dhofarensisare
alike (Figs. I and2).A few minor differencescanbe observedin somespecimens,
but they arenot suitablefor taxonomicpurpose.The secondarysexualcharacters
of both the nominal form and the subspecies
are alike.
Female.Disc of pronotumwith two latero-basalcorrugatedfields, not extending
to the yellow areas.Genitalpiecesnot studied.
Distribution.Only known from the Dhofar region,Oman.
Biology. The new taxonwas collectedfrom sidepools of streamsand springs,and
at light.
Discussion
Hydaticussatoi dhofarensisn. ssp.can be identified at sight becauseof its size,
the body shapeandthe colourpattern.As for colour,dark specimensof Hydaticus
vittatus andHydaticusbipunctatusWehncke,l8l6 (seeWnwarx.d,1975:figs. 6
and l1) can be mistakenfor sqtoi dhofarensisbut they are smalleras a rule. Dark
specimensof satoi dhofarensishave a resemblancewith Hydaticus daemeli
Wehncke,1876from Australia,which is similar in size and colour,but differs in
other characters.
The subspecies
andthenominalform arecloselyrelatedto othertaxaof thevittatus
groupwith a similar aedeagus,principallyHydqticusvittqtus(Fabricius),Élydaticus
22
majorRégimbart,1899andHydaticusarabicusGuignot,1951.The closestspecies
is Hydaticusvittatus(Fabricius),but its medianlobe of the aedeagusis narrower
in lateral view and pointed at apex in dorsal view (Figs. 3 and,4), while it is
widenedapically in satoi.
H. vittatus andH. major were revisedby Wrwarre (1915).Hydaticusarabicus
Guignot,describedon two malesfrom Hadramaut(GutcNor,195l), was revised
and figured by BneNcuccr(1981).
This speciesis geographicallycloseto H. satoi dhofarensisand is similar in size.
The principal differenceslie in the colourpatternof elytraandthe narrowerpenis
of arabicus,in sideview2.
The remaining membersof the vittatus group and the Afro-Malagasy Hydaticus
bivittatusLaportede Castelnau,1835have afairly differentshapeof the aedeagus
and cannotbe confusedwilh satoi.
Waterbeetlesfound in associationwifh Hydaticussatoi dhofarensisn. ssp.
Fig. 8 - Length and ratio ofwidth to length of H. satoi sctoi (white triangles) and H. satoi dhofarensis (black
triangles).
2The median lobe of the aedeagusin H. satoi and its allied is about 3 mm long, however according
arabicusisapproximatelyhalfaslongasin
tothescale-barbyBneNcuccr(1981),thepenisoflL
other specìes.
ZJ
Fam. Gyrinidae
DineutusaereLrs
Klug, 1834
2 exx. "Wadi Hinna, 17"03,20'N- 54'36,56'E, m 350, 10.IX.2002"; I ex. "Wadi
Darbat,belowRd.49, 17o03,16
N - 54'25,60F.,1.IX.2002";1 ex. "Wadi Darbat,
basecascata[below waterfall], Hg light, 11.IX.2002".
Fam.Dytiscidae
Hyphydruspictus Klug, 1834
I ex. "Ain Sanahawq,
17"08,64N - 54"10,85'E, m 130,5.IX.2002":1ex. "Wadi
Hinna, 17"03,20'N 54'36,56'E, m 350, 10.IX.2002".
Hydroglyphusl: Guignotus)major (Sharp,1882)
I ex."JabalSamhan,
E of Hyoor,17o07,88'N- 54'43,99'E,m 1350,14.IX.2002".
Eretessticticus(Linnaeus,1767)sensuMrI-r-en(2002)
1 ex. "Al Mughsayienvir.,16"53,01N - 53o46,418,6.IX.2002".
CybistertripunctatusafricanusLaportede Castelnau,1835
1 ex. "Wadi Hinna, 17"03,20'N- 54"36,56'E. m 350. 10jX.2002".
Fam.Hydrophilidae
Temnopterus
aculeatusSolier, I 834
1 ex. "Wadi DarbaI,below Rd. 49, 17"03,16N - 54o25,608,j.IX.2002"; 2 exx.
"Wadi Darbat,
basecascata[below waterfall], Hg light, ll.IX.2002".
Acknowledgement
Thanks are due to Dr. Marco Dellacasa(Pisa)who kindly lent the material for
identificationand supportedthe studywith informationand advice.
References
BnaNcuccr
M., 1980- Insectsof SaudiArabia.coleoptera:
Fam.Hatiplidae,
Dytiscidae,
Gyrinidae.
Part2.Faunaof SaudiArabia,2:102-111.
parl3.Fauna
BnaNcuccr
M., 1981- Insects
of SaudiArabia.coleoptera:
Fam.Dytiscidae.
oJSaudiArabia,3:227-230.
GutcNorF., 195I - Hydaticusnouveauxde la collectionRégimbart.RevueFranqaise
d'Entomologie,
18:21-24.
Mtt-ronK.B.,2002 Revisionof theGenus
EretesLaporte,1833(Coleoptera:
Dytiscidae).
AquaticInsects,24 (4):247-212.
wewerxa.G., 1975- Revisionder ArtengruppedesHydaticusvittatus(Fabricius).
Koleopterologische
Rundschau,52:87-I 00.
Author's address:
FernandoPederzani
via Landoni,35 I-48100Ravenna
e- ma i I : p [email protected]
zn