Simulium (Inseliellum) littopyga Craig & Evenhuis, 2017

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

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

FIgs. 1–15 .

Description. Adult female (based on 21 specImens). Body ( FIgs. 1 ): overall dark brown, abdomen occasIonally mottled ventrally; total length 2.0– 2.6 mm. Head ( FIg. 2 ): 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 ): 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 ) 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 ) 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 ); katepIsternum dark brown, sulcus dIstInct. Wing ( FIg. 7 ): 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 ); claw ( FIg. 10 ) wIth maIn talon well curved and evenly tapered, basal tooth 0.25x length of claw, thumb-lIke, heel small. Abdomen ( FIg. 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 ), 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 ), surface lIghtly wrInkled, Internal spInes (acanthae) absent, membranous area at junctIon wIth spermathecal duct not dIstInct; genItal fork ( FIg. 14 ) 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 ).

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].

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 ) and spermatheca ( FIg. 13 ) are markedly dIfferent (CraIg 1987: cf. hIs FIg. 4 ).

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).

Figures

FIGURES 1 – 6. Simulium (I) littopyga n. sp. (1). Holotype, female Simulium (I.) littopyga. In ETOH. Scale bar = 0.5 mm. (2) Frontal view of head. Scale bar = 0.2 mm. (3). Antenna. Scale bar = 0.1 mm. (4). Maxillary palp, mandible, lacinia. Scale bar = 0.1 mm. (5). Mandible apex. Scale bar = 0.02 mm. (6). Cibarium. Scale bar = 0.05 mm.

FIGURES 7 – 11. Simulium (I.) littopyga n. sp. (7). wing. Scale bar = 0.5 mm. (8). Anepisternal membrane. Scale bar = 0.1 mm. (9). Hind basitarsus, calcipala, pedisulcus. Scale bar = 0.1 mm. (10). Claw & basal tooth. Scale bar = 0.05 mm. (11). Abdominal tergites. (Holotype, dried). Scale bar = 0.5 mm.

FIGURES 12 – 15. Simulium (I.) littopyga n. sp. (12). Hypogynial valves. Scale bar = 0.1 mm. (13). Spermatheca. Scale bar = 0.02 mm. (14). Genital fork. Scale bar = 0.05 mm. (15). Cercus & anal lobe. Scale bar = 0.05 mm.