A new species of water scavenger beetle, Coelostoma (s. str.) tina (Coleoptera: Hydrophilidae: Sphaeridiinae), from Kenya, eastern Africa

8 Pages·2003·2.3 MB·

by  Paul J Spangler

PROC. ENTOMOL. SOC. WASH.
\i)M1).2003,pp. 1-8
A NEW SPECIES OF WATER SCAVENGER BEETLE. COELOSTOMA
(S. STR.) TINA (COLEOPTERA: HYDROPHILIDAE: SPHAERIDIINAE),
FROM KENYA, EASTERN AFRICA
Paul J. Spangler and Warren E. Steiner, Jr.
Department ofSystematic Biology-Entomology. National Museimi ofNatural History,
Smithsonian Institution, Washington. DC 2(),'i60-0187, U.S.A. (e-mail: steiner.wanen@
nmnh.si.edu)
—
Abstract. A newspeciesofAfricanwaterscavengerbeetle,CoelostomatiiiaSpangler
and Steiner, is described. The specimens were collected in an eastern African section of
the Rift Valley from lagoons in Lake Magadi. Kenya, and pools adjacent to the lake. The
water in these habitats is hypersaline and highly alkaline and shores are salt encrusted.
The adults are described and illustrated with line drawings and scanning electron micro-
graphs. Habitat notes and photographs ofthe biotope are given.
Key Words: aquatic insects. Afrotropical fauna, extreme environments, salt lakes
The new speciesofwaterscavengerbee- ma orbiciilare (Fabricius) in the Palearctic
tle described in the following account was Region from Britain to West Siberia, south
collected by Scott E. Miller and Tina M. to Spain and east to Japan. Also, Coelos-
Kuklenski during biodiversity Heldwork in toma fabricii (Montruzier) is reported by
Kenya, eastern Africa. The specimens were Hansen frommanycountriesintheOriental
collected in the RiftValley at the siteofthe and Australian Regions as well as the Pa-
Magadi Soda Company in hypersaline and cific Islands (Hawaiian Islands).
highly alkaline water in lagoons in Lake The genus Coelostoma was described by
Magadi and in adjacent pools. The speci- Brulle (1835). Since that time numerous
mens belong to the genus Coelostoma. a new species were described by a variety of
speciose genus that is widely dispersed in authors, mostly in small contributions and
the Eastern Hemisphere tropics. Most re- often under other incorrect generic or spe-
cently, Hansen (1999) in his catalog ofthe cies names. The genus was first revised by
Hydrophiloidea ofthe world listed 92 spe- d'Orchymont (1936), 101 years afterBrulle
cies and 9 subspecies of Coelostoma. Of originated the genus. Fortunately
thesetaxaapproximately70'7rareAfrotrop- d'Orchymont. a prolific hydrophilid spe-
ical, 25% are Oriental, and the remaining cialist, describedand illustrated theaedeagi
5% are reported from the Palearctic and of his 15 new species plus 9 species de-
Australian regions. Most species inhabit scribed by earlier authors. In his study he
lenticfreshwaterhabitatsinweedymargins. found that it was absolutely necessary to
Some, and probably most species, can f\y ignore the females and to perform the te-
and are attractedtoultraviolet, mercury va- dious extractions of the aedeagi, illustrate
por, and incandescent lights. Some species them, and segregate species on theirdiffer-
are highly vagile, therefore, widely distrib- ences. In a subsequent publication,
uted (fide Hansen 1999) such as Coelosto- d'Orchymont (1940) divided the genus into
.
PROCEEDINGSOFTHEENTOMOLOGICALSOCIETYOFWASHINGTON
two subgenera, the nominate Coelostonia dish brown; apical segments 7-9 pubescent
(s. str.) and his new subgenus. Lachiiocoe- and dark reddish brown. Labrum reddish
lostoma. brown across anterior margin and bearing
Later, Mouchamps (1958) followed shortgoldensetae. Maxillaryandlabialpal-
d'Orchymont's advice and primarily based pi reddish yellow. All visible abdominal
his descriptions of 25 new species and re- sterna with reddish brown oval spot adja-
descriptions of six previously described cent to lateral margins.
species on their distinctive male genitalia. Head: Shiny, moderately coarsely and
Occasionally, he noted differences in size densely punctate, punctures separated by Vi
and density ofpunctation and microreticu- to 3 times puncture diameter; surface be-
lation on dorsal and ventral surfaces of tween punctures finely microreticulate. A
some species. However,bothauthorsessen- patch of hydrofuge pubescence posterolat-
tially used only the distinctive aedeagi to eral to each eye continues under head over
distinguish the different species includedin genae except for a glabrous, longitudinal,
their publications. In Mouchamps's article cariniform ridge on midline between two
noted above, he also described two new similarly glabrous, but angular ridges (Fig.
subgenera, Hammacoelosloma and Holo- 5) bordering each hydrofuge pubescent
coelostoiuii, and provided a key to the four patch. Labrum finely, densely punctatedor-
subgenera presently known. sally and shallowly and broadly emarginate
anteriorly. Mentum rimmed, shallowly
Coelostoma (s. str.) tina Spangler and emarginate apicomedially, shallowly con-
Steiner, new species cave on anterior half, moderately coarsely
—(Figs. l-IO) anddenselypunctateonposteriorhalf.Sub-
Diagnosis. Colormostlyblack,shining, mentum punctate as on mentum but over
body oval, strongly convex dorsally (Figs. entire surface.
1-3); length 4.6-5.5 mm. Antenna 9 seg- Thorax: Pronotum widest subbasally,
mented: base concealed under lateral shelf lateral margins arcuate; anterolateral and
of head (Figs. 4—5). Mesosternal process posterolateral angles rounded: punctureson
sagittate and without a small transverseca- disc moderately coarsely, densely punctate;
rina (Figs. 6-7). Tarsal claws simple. Me- punctures separated by 1 or 2 times punc-
tasternum with posterior process extended ture diameter; surface between punctures
between metacoxae and forked apically microreticulate. Prosternumwithonlyami-
(Fig. 8). Profemora and mesofemora with nute denticle apicomedially followed by a
dense, stiff, hairlike setae on upper surface low, ovoid medial hump. Mesosternum
and similar but sparser setae on lower sur- with broad sagittate medial protuberance
face. First abdominal sternum not carinate with an apical hooklike process (Fig. 6); in
longitudinally on midline. Last abdominal ventral view, sides rimmed; a longitudinal,
sternum rounded, not notched apicomedi- pubescent, medial process extends posteri-
ally. Aedeagus distinctive (Figs. 9-10) for orly andmeetsmetasternal processbetween
this new species, resembling most closely mesocoxae (Fig. 7). Metasternumshinyand
that of C. austrine Mouchamps (1958) but ovately raised medially; densely and
in general more elongate with apices ofthe coarsely punctate laterally and more than
parameres less—pointed. on raised discal area; posterior process ex-
Holotype S Bodyformandsize: Oval, tended between metacoxae and apex bifur-
strongly convex dorsally. Length 5.3 mm; cate (Fig. 8). Metepisterna pubescent. Pro-
width 3.1 mm. coxa sparsely, finely setose. Profemur
Color: Black and shiny dorsally. Venter densely punctate and pubescent on basal
blackexcept tarsi dark reddish brown. Bas- four-fifths on all sides except on upper
al antennal sesments 1-6 glabrous and red- (leading) edge. Mesofemurdensely,coarse-
VOLUME lOS.NUMBER 1
Figs. 1-6. Cot'lostoinuuna.male,scanningelectronmicroscopeimages. 1,Dorsalhabitus.2.Ventralhabitus.
3,Obliquefrontalview.4,Leftantennaandmaxillarypalpus,dorsalview.5,Head,ventralview.6,Mesosternal
process,lateral view.
ly punctate as on profemora. Metafemur stria is separated from suture by diameter
similarto mesofemurbutwith fewercoarse of an adjacent elytral puncture then deep-
punctures. Elytron with random punctures ening and widening to a distance equal to
moderately coarse and dense, punctures thediametersof4adjacentpuncturesately-
separated by 1-2 times diameterofa punc- tral apex. Scutellum an elongate triangle;
ture; side nearly vertical from base to pos- coarsely and densely punctate but more
teriorendofmetepisterna; with suturalstria finely microreticulate than on pronotum.
extending from apex of scutellum where GeiiitaHa: Aedeagus (Fig. 9) with me-
I'ROd IMNGSOFTHEENTOMOLOGICALSOCIETYOFWASHINGTON
1
Figs.7-8. Coelostomatiiia. male,scanningelectronmicroscopeimages.7,Coxaeandthoru
igsagittatemesosternalprocess.8,Forkedprocessofmetasternumbetweenmetacoxae.
dian lobe wide at base, then tapering to rican Museum, Tervuren, Belgium; and the
apex: parameres flattened and widest at Transvaal Mus—eum, Pretoria, South Africa.
apex, angled inward, and upturned on api- Etymology. We take pleasure in nam-
cal Vi (Fig. 10); gonoporeopeningventrally ing this beetle for Tina Kuklenski Miller,
at apex. who. according to Scott Miller, urged him
Typedata.—Holotype((J): KENYA; Ka- to stop at the site and take samples of in-
NW
jiado District, Lake Magadi, Lagoonat sects, leading to the discovery ofthis new
shortcut road. 1.805°S. 36.05TE, ca. 600 species.
m; Station 3, 31 January 1999, S. E. Miller
& T. M. Kuklenski collectors. Allotypeand Habitat and Hlstory
6 paratypes, same data; 24 paratypes, same According to investigations by Vincens
NW
dataexcept; Lagoonundersaltencrust- and Casanova (1987) and Roberts et al.
ed rocks at edge of lake, 11 June 1997, (1993), Lake Magadi lies at 1°50'S,
1.850°S, 36.217°E; 600 m. The holotype 36°I8'E, 600 m above sea level and is a
and3paratypeswillbedepositedintheNa- closed lake at the southern end ofGregory
tional Museum of Kenya, Nairobi. Para- Rift Valley in Kenya (Fig. 11). Exploited
types will be deposited in the National Mu- commercially since 1917 by the Magadi
seum of Natural History, Smithsonian In- Soda Company, it is described as an active
stitution, Washington. DC; The Natural salt lake with thick tronadeposits and con-
History Museum, London; the Central Af- centrated alkalinebrines.Theclimateishot
VOLUME 105. NUMBER I
Figs. 9-10. CoelostoiIII liiiii. male genitalia, line
drawings.9.Dorsalview. 10. Lateral view. Fig. 11. Mapof the lealiiresand locationol Lake
Magadi-Natron basin. Kenya (from Roberts et al.
199.^).thetype localityofCocliislmiuiliini.
and dry which, along with the prevaihng
lava and rocks, produces a harsh, semi-arid the lake probably fluctuate with rainfalland
landscapeofgrasslandandshrubland. Hand evaporation.
axes and other artifacts were discovered in
1942 by M. Leakey, andearly hominid fos- Biota and Endemi.sm
silsweredescribedfromtheregion(Leakey The biota of Lake Magadi and its envi-
and Leakey 1964), indicating that the area rons has not been thoroughly surveyed; se-
has a long history of human utilization. lected taxa have been studied but the insect
Baker (1958) reported that the first Euro- fauna is virtually unknown. Roberts et al.
pean to visit the area was a geologist, A. (1993) refer to two flamingo nurseries in a
Fischer, in 1883. He was followed by nu- lagoon in the northwestern section ofLake
merousothergeologistsand achemist,J. A Magadi (these birds currently provide an
Stevens (ca. 1930), from the Magadi Soda important tourist attraction to many East
Company. Stevens provided valuable anal- African lakes). Because flamingos usually
yses of alkaline spring waters, lagoon li- feed on zooplankton, phytoplankton, crus-
quors, and various salts that he found in taceans (amphipods, brine shriinp), insects
Lake Magadi and adjacent hypersaline and (ephydrid and chironomid larvae), oligo-
alkaline waters. The lake is fed almost en- chaetes, etc. (Allen 1956), it seems reason-
tirelybygroundwaterinflowsfrommodern able that some ofthese organisms occur in
springs (with their pH ranging from 9-9.5) the shallow water in or near the flamingo
while the larger Lake Natron, which was nurseries ofthe lake. However, Lesser Fla-
formerly connected to Lake Magadi, re- mingos (the species breeding at Lake Ma-
ceives substantial surfacewaterinflowspri- gadi)arespecializedfeedersondiatomsand
marily from the Ewaso Ngiro River. Salin- blue-green algae, and larger food items
ities of the various parts and side pools of such as midge larvae and copepods occur
PROCEEDINGSOFTHEENTOMOLOGICALSOCIETYOrWASHINGTON
Figs. 12-13. Biulopcol the typeloculilyofCoelostomaliihiat LakeMagadi, Kenya. 12.Lakemarginand
side pools withemergent rocks. 13. Partoflakebasinwith shallowpool in foreground, oneofthe collection
sites. Photographsby R.Copeland.
VOLUME 105, NUMBER I
in the less extremely alkaline lakes of the esting to compare the modern assemblages
region(Brown 1973).Theextremeenviron- of species ofthe two lakes.
ment of Magadi and the historical exploi-
tation of the site makes the occurrence of Acknowledgments
the new species of water scavenger beetle We thank Scott and Tina Miller for col-
most remarkable. lecting these beetles for our study and for
Scott Miller (in litt.) reported that the providing references to the history, geolo-
lake and pools have many emergent rocks gy,geographyandbiotaoflakeMagadiand
that provide hiding places forinvertebrates. its harsh environs. The sampling was con-
In association with Coelostonui tina, Miller ducted as an activity of the International
and Kuklenski collected the following or- Centre of Insect Physiology and Ecology
ganisms fromthe northwest lagoon: aprob- (ICIPE), in cooperation with National Mu-
ably new species ofspiderbelonging tothe seums of Kenya. We thank the Magadi
genus Wiulicosa; two whirligig beetles be- Soda Company for providing ICIPE access
longingtothegeneraOrectogyrusandGyr- totheirlandand KenyaWildlifeServicefor
iniis. and the cosmopolitan earwig, Lahi- providing export permits. Robert Copeland
cliira riparia (Pallas). allowed us to use his photographs of the
In addition, the following organisms lake habitat. Jerry Cassis from the Austra-
from the Lake Magadi system have been lian Museum identified theearwig. Wealso
described or discussed by variou.s authors thank Young T Sohn. Biological Illustrator,
as follows. The tiger beetle Lophyni pseii- for the line drawings, Susann Braden and
dodistans (Horn) is apparently endemic to Scott Whittakerforassisting withoperation
the area (Werner 1993). A dwarf cichlid of the scanning electron microscope and
fish, Tilapia grahanii Boulenger is present- preparation ofthe SEM images and plates,
ly living in more dilute parts ofthe lake as and George Venable, Graphics Illustrator,
has been reported by Baker (1958); this for formatting the other illustrations and
species has been recently used as a subject photographs. Comments by Philip D. Per-
foran experimental study ofitsadaptations kins and one anonymous reviewer on the
to its highly alkalineenvironment (Woodet manuscript are appreciated.
al. 1994). Microbiologists isolated and de-
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