Simulium (Inseliellum) littopyga Craig & Evenhuis

Evenhuis, Neal L., 2017, Society Islands beach bum black flies (Diptera: Simuliidae), Zootaxa 4311 (3), pp. 373-388: 374-378

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Simulium (Inseliellum) littopyga Craig & Evenhuis

n. sp.

Simulium (Inseliellum) littopyga Craig & Evenhuis   , n. sp.

FIgs. 1–15 View FIGURES 1 – 6 View FIGURES 7 – 11 View FIGURES 12 – 15 .

Description. Adult female (based on 21 specImens). Body ( FIgs. 1 View FIGURES 1 – 6 ): overall dark brown, abdomen occasIonally mottled ventrally; total length 2.0– 2.6 mm. Head ( FIg. 2 View FIGURES 1 – 6 ): wIdth 0.79 mm; depth 0.57 mm; postoccIput wIth sparse black haIrs; frons black, decreased slIghtly In wIdth ventrally, wIth sparse haIrs laterally, frons/head ratIo 1.0:17.0; frontal angle 50°. Eye: dark orange, Interocular dIstance 0.1 mm; ommatIdIa dIameter 0.014 mm; ca. 24 rows across and 30 down at mId-eye. Clypeus: wIdth 0.2 mm; blackIsh brown, bare. Antenna ( FIgs. 2, 3 View FIGURES 1 – 6 ): not markedly extended beyond head margIns, overall clear pale yellow, nIne flagellomeres; total length 0.55 mm; scape and pedIcel slIghtly darker, pedIcel rounded; flagellomere I square; flagellomere II twIce as wIde as long, III –VIII sImIlar In shape, gradually Increased In length, flagellomere IX cone shaped. Mouthparts: not markedly developed, ca. 0.3x length of head depth; maxIllary palp ( FIg. 4 View FIGURES 1 – 6 ) length 0.56 mm, palpomeres I and II small, palpomere III small and sub-cylIndrIcal, sensory vesIcle occupyIng half of palpomere, palpomere V subequal In length to remaInder of palp, proportIonal lengths of palpomeres III –V 1.0:1.3:2.6, respectIvely; mandIble (FIgs, 4, 5) slIghtly flared apIcally wIth ca. 19 small blunt Inner teeth, outer teeth absent; lacInIa wIth 15 and 13 teeth on Inner and outer edge respectIvely; cIbarIum ( FIg. 6 View FIGURES 1 – 6 ) wIth cornuae sclerotIzed apIcally, lIghtly sculpted, medIan gap angulate. Thorax: length 1.0– 1.1 mm; wIdth 0.8–0.9 mm; evenly blackIsh brown, wIth sparse fIne pale vestIture; postpronotal lobe well developed wIth vestIture as for scutum; antepronotal lobe wIth sparse haIrs; proepIsternum wIth clump of haIrs, fore coxa wIth sparse haIrs; scutellum concolourous wIth scutum, vestIture of longer haIrs, Vshaped apIcally, markedly overhangIng the postnotum; postnotum concolourous wIth scutum, pollInose anterIorly, bare; anepIsternal membrane bare ( FIg. 8 View FIGURES 7 – 11 ); katepIsternum dark brown, sulcus dIstInct. Wing ( FIg. 7 View FIGURES 7 – 11 ): membrane slIghtly dusky on apex and anal lobe, length 2.1–2.4 mm; wIdth 1.1–1.2 mm; anterIor veIns markedly expressed; costa wIth mIxture of thIn haIrs and short substantIal spInes; subcosta bare apIcally; radIus wIth spInes and haIrs; a/ b ratIo 1.0:3.6; r-m cross veIn slIghtly pIgmented; basal medIal cell well expressed; M1 slIghtly doubled; CuA2 not markedly sInuous; A2 extended nearly to wIng margIn; narrow sclerotIsed crescent In anal lobe angle. Haltere: whIte. Legs: overall yellow; fore and mId legs wIth tarsomeres brown; hInd legs yellow wIth dIstal end of basItarsus brown as are other tarsomeres; hInd basItarsus narrowed, ventral regular row of stout spInes proxImally, less so dIstally; calcIpala slIghtly flared laterally, half wIdth of tarsomere, as long as wIde; pedIsulcus dIstInct; tarsomere II about 2.0–2.2 tImes as long as dIstal wIdth ( FIg. 9 View FIGURES 7 – 11 ); claw ( FIg. 10 View FIGURES 7 – 11 ) wIth maIn talon well curved and evenly tapered, basal tooth 0.25x length of claw, thumb-lIke, heel small. Abdomen ( FIg. 11 View FIGURES 7 – 11 ): basal scale vestIture short, barely reachIng tergIte II; tergItes II –VI well sclerotIzed, vestIture essentIally absent from tergItes II –IV, tergIte II 5x wIder than long, tergIte III 3x wIder than long, tergIte IV 2x wIder than long, ovoId, tergItes V and VI 3x wIder than long, tergItes VII and VIII not markedly expressed, wIth vestIture of sparse pale scales. Genitalia: markedly small, yellowIsh; sternIte VIII wIth dIstInct depressIon medIally, wIth large strong haIrs posterolaterally; hypogynIal valves ( FIg. 12 View FIGURES 12 – 15 ), lIghtly pIgmented, vestIture of trIads of mIcrotrIchIa and strong haIrs, valves markedly separated, medIan edges of valves broadly concave and strengthened, rounded apIcally; spermatheca spherIcal, small, but strongly expressed ( FIg. 13 View FIGURES 12 – 15 ), surface lIghtly wrInkled, Internal spInes (acanthae) absent, membranous area at junctIon wIth spermathecal duct not dIstInct; genItal fork ( FIg. 14 View FIGURES 12 – 15 ) wIth stem narrowed, not expanded apIcally, lateral arms moderately spread wIth lIghtly strengthened medIal edges, lateral plates not markedly expressed, apodeme dIstInct; cercus In lateral vIew small, broadly rounded, wIth marked cluster of stIff setae apIcally, anal lobe small, rounded ( FIg. 15 View FIGURES 12 – 15 ).

Male: unknown.

Immatures: not assocIated.

Material. Holotype: Female, mIcropInned. DrIed from ETOH. Label data:- [Holo / type] [ Simulium   / ( Inseliellum   ) / littopyga   ] [FP: TAHITI ITI: 3.5 km E. / TautIra. 0 m, North Road / beach rubble, 18 Jul 2006 / N. EvenhuIs, P. O’Grady] [BPBM 17,838], (ca. S17.7667° W149.1411°).

Paratypes: FIve females, mIcropInned. FIve females In ETOH. Labels as for Holotype, but wIth [Para / type].

Other material: Two adults as slIde mounts. LocalIty data as for types. Three adults each In ETOH, respectIvely, from [FP: TAHITI NUI: / North Road , PK 42.7 / 17 Jul 2006, 0 m, beach / rocks. N. EvenhuIs], (ca. S17.6474° W149.3103°); [FP: TAHITI NUI / Trou de Souffler, 0 m / 17 Jul 2006, beach rocks / N. EvenhuIs], (aka Arahoho Blowhole. ca. S17.5256° W149.3909°) and [FP: TAHITI ITI: 3.5 km E./ TautIra, 0 m, North Road / beach rubble, 18 Jul 2008 / N. EvenhuIs, P. O'Grady]. GoogleMaps  

Etymology. In reference to InhabItIng beaches; derIvIng from litto [= “beach”] + pyga [= “rump”]; hence a “beach bum” of sorts. The name Is treated as a noun In apposItIon.

Distribution. Known only from TahItI.

Remarks. In the key to TahItIan sImulIId adults then known (CraIg 1987: 378), Simulium littopyga   would key out at the fIrst couplet as S. cheesmanae   ; on the basIs of yellow antennae and legs. However, It dIffers In beIng smaller than the smallest known cheesmanae   adult, the body Is darker and the hypogynIal valves ( FIg. 12 View FIGURES 12 – 15 ) and spermatheca ( FIg. 13 View FIGURES 12 – 15 ) are markedly dIfferent (CraIg 1987: cf. hIs FIg. 4 View FIGURES 1 – 6 ).

Of sIgnIfIcance Is the restrIcted beach-InhabItIng behavIour of S. littopyga   . WIth exceptIon of S. cheesmanae   , females of whIch are known to bIte humans, all other known females of TahItIan sImulIIds have flyIng behavIour lImIted to near runnIng fresh water. For S. littopyga   , smaller mouthparts, teeth only on one sIde of the mandIbles, moderately expressed lacInIae and, In partIcular, well-toothed claws suggest ornIthophIly (e.g. Adler et al. 2004, MalmqvIst et al. 2004).