Polyrhachis lama, a new ant from the Tibetan plateau (Formicidae: Formicinae).

2 Pages·1994·0.08 MB·English

by  Kohout, R. J.

POLYRHACHISLAMA, A NEW ANTFROMTHETIBETANPLATEAU (FORMICIDAE:
FORMICINAE)
RUDOLF KOHOUT
J.
Kohout,R.J. 19940601:Polyrhachislama,anewantfromtheTibetanplateau(Formicidae:
Formicinae). Memoirs ofthe QueenslandMuseum 35(1):137-138. Brisbane. ISSN 0079-
8835.
Polyrhachislamasp.nov. isdescribedfromtheTibetanplateauofCentral Asiaasthe first
speciesoftheP.vie^meyen-grouprecordednorthoftheequator.Itissuggestedthatspecies
ofthegroupwereinthepastmorewidelydistributedandthatP. lama isarelictsurviving
in isolation on the high plateau ofTibet. OFormicidae, Polyrhachis, viehmeyerispecies-
group, newspecies, distribution.
RudolfJ. Kohout, QueenslandMuseum, POBox3300, South Brisbane, Queensland4101,
Australia;20December1993.
ThisnewmemberoftheP. viehmeyerispecies- convergingdorso-lateralcarinaealmostreaching
groupischaracterisedbytheabsenceofpronotal the anterior pronotal margin. Promesonotal su-
spines, and abundance of distinctly shaggy ture well impressed, metanotal groove rather ill
pubescencebeneaththebristle-likepilosity. defined. Propodeal spines well elevated, only
Measurements (mm) and indices follow slightly divergent. Dorsum of petiole convex,
Kohout (1990): TL, total length; HL, maximum anterior and posterior margins obsolete; spines
head length; HW, head width immediately in wellelevated, divergent.
frontofeyes; CLcephalic index (HWxlOO/HL); Clypeus, frontal and lateral areas of head,
SL, scape length excluding condyla; SI, scape lateral branches of mesosoma and petiole
index (SLxl(X)/HW); PW, pronotal widthacross moderately rugose; rugosity increasing dorsally
humeri; MTL, metathoracic tibial length. andposteriorlywithdorsaofheadandmesosoma
fairly coarsely vermiculate-rugose. Gastral dor-
SYSTEMATICS sum opaque, striate-rugose, with sculpture
pi;ogressively lessdistinctposteriorly.
Polyrhachislama sp.nov. Moderatelylong,yellowishandreddishbristle-
(Fig.l) like hairs fairly dense on all body surfaces, in-
cluding appendages. Silvery pubescence, of
MaterialExamined distinctly shaggy appearance, rather dense, ex-
HOLOTYPE: Tibet (=Xizang Zizhiqu, China). cept on promesonotal dorsum where it is some-
'Deutsche Tibet-Expedit. 1938-39 (E. Schiifer)' whatless abundant.
(worker). Generallydarkreddishbrownwithhead,meso-
Paratypes:dataasforholotype(4workers, 1 dealate somaandpetioleondorsal aspectpiceous. Man-
female). dibles, appendages andgastera shade lighter.
All in the Forschungsinstitut Senckenberg; Female. Dimensions: TL c. 9.07; HL 1.96;
paratypeworkerin QueenslandMuseum. 1.53;CI78;SL2.28;SI149;PW1.71;MTL2.97
(1 measured).
Description Besides the usual characters identifying full
Worker. Dimensions (holotype cited first): TL sexuality,thegeneralappearanceoftheavailable
c.8.11,8.32-8.72;HL 1.93, 1.87-2.03;HW 1.50, singlefemaleresemblestheworkerveryclosely.
1.47-1.56; CI78, 75-79; SL2.31, 2.21-2.40; SI Pronotal humeri with short, ill-defined carinae.
153, 150-155; PW 1.03, 0.97-1.06; MTL 2.97, Propodealand petiolarspinesshorter,theformer
2.87-3.07 (5 measured). slightly, the latter rather more divergent.
Clypeus with deeply impressed basal margin; Sculpturationsimilartothatofworker,withden-
medianlongitudinalcarinadistinctanteriorly,in- sity increasing from moderately rugose to fairly
distinct posteriorly; median portion of anterior coarsely vermiculate-rugose,namelyonthehead
margin dentate laterally. Median ocellus andmesoscutum,contrastingsharplywiththaton
rudimentary, lateralocellilacking.Pronotumun- mesoscutellum where it is distinctly less coarse
armed; humeri produced into distinct, forward with somewhatgranularappearance. Bristle-like
MEMOIRSOFTHEQUEENSLANDMUSEUM
138
and abundant shaggy pubescence almost
obscurestheunderlyingsculpturation.
Maleand immaturestages unknown.
Remarks
Known distributionoftheviehmeyeri-gxou^is
from the Moluccas through Papua New Guinea
to the Solomon Islands and northern Australia
(Kohout, 1990)butthiscouldbeunderestimated.
With thedescription ofP. lama itappears that
thegroupwasinthepastmorewidelydistributed
and, perhaps, lama is an isolated relict. The un-
deniablesimilaritybetweenP. lamaandthevieh-
meyen'-groupprototypeshowsthatbothprobably
derivedfromthe same ancestral stock. As noted
eariier (Kohout,1990:506), most of this group
exhibitvariabilityinthelengthofpronotalspines
evenwithinthesamepopulation.Theircomplete
absence and replacement by forward produced
carinae, as seen in lama, demonstrates their
variability to theextreme and can be interpreted
as a product of an independent development of
thespecies in isolation.
ACKNOWLEDGEMENTS
Dr J.-P. Kopelke and Wolfgang H.O. Dorow
generously provided access to the Forschung-
My
sinstitutSenckenberg collection. gratitude is
expressed to the Australian Entomological
Society, fora ResearchyTravel Grant. I thankDr
Kevin J. Lambkin, Queensland Museum, for
readingthedraft manuscript.
LITERATURECITED
FIG. 1.Scanningelectronmicrographoftheuncoated
holotypeofP. lamaindorsalview.
KOHOUT, R.J. 1990. A review of the Pofyrhachis
pilosity is definitely more dense than in worker viehmeyeri species-group. Memoirs of the
QueenslandMuseum28: 499-508.