Namibimydas gaerdesi Hesse

Dikow, T., 2012, Review of Namibimydas Hesse, 1972 and Nothomydas Hesse, 1969 (Diptera: Mydidae: Syllegomydinae: Halterorchini) with the description of new species, African Invertebrates 53, pp. 79-111 : 83-86

Namibimydas gaerdesi Hesse ,1972

Figs1-3, 13, 14, 21, 43

Namibimydas gaerdesi :Hesse1972:161.

ZooBank LSID:see Table1.

Diagnosis:The species is distinguished from congeners by the long proboscis that extends beyond the distal tip of the postpedicel(Fig.13),the long abdominal setation in both males and females,the yellowish mystax(Figs13, 14),and its apparent distribution in coastal(or near coastal)habitats from Swakopmund to Sandwich Bay in Namibia(Fig.43).

Redescription:

Male.

Head:Black,in general densely grey pubescent;width distinctly greater than thorax,interocular distance on vertex larger than at ventral eye margin,vertex between compound eyes more-or-less horizontally straight,medially only slightly below dorsal eye margin,parafacial area less than half the width of central facial gibbosity;facial gibbosity distinct,well-developed and discernible in lateral view;mystax white to yellowish,covering entire facial gibbosity;frons entirely grey pubescent,vertex entirely grey pubescent,postgena apubescent;setation:vertex white,frons white,ocp setae white,pocl macrosetae light brown;ocellar triangle apubescent;proboscis brown,long,projecting well-beyond fronto-clypeal suture and beyond tip of postpedicel;labellum small,as wide as prementum,about quarter length of prementum,unsclerotised laterally;maxillary palpus cylindrical,light brown,as long as pedicel.

Antenna:Brown,scape and pedicel white setose dorsally and ventrally;postpedicel cylindrical in proximal0.4,symmetrically bulbous in distal0.6,≥5.0 × as long as scape and pedicel combined;apical ‘seta-like’ sensory element situated apically in cavity on postpedicel.

Thorax:Brown,predominantly grey pubescent;scutum medially dark brown,laterally brown,surface entirely smooth,lightly grey pubescent,broad sublateral stripes(interrupted postsuturally)and narrow paramedial stripes(not reaching posterior margin)apubescent,scutal setation comprised of long white setae with distinct rows of long dc setae and dense lateral scutal setae;dc setae pre- and postsuturally white,acr setae present,lateral scutal setae white,npl setae0,spal setae0,pal setae0;postpronotal lobe light brown,grey pubescent;proepisternum,lateral postpronotum,and postpronotal lobe long white setose;scutellum grey pubescent,asetose,apical scutellar setae absent;mesopostnotum,anatergite,and katatergite grey pubescent,mesopostnotum asetose,anatergite asetose,katatergite long white setose;katatergite more-or-less flat;anterior anepisternum asetose,supero-posterior anepisternum long white setose;posterior anepimeron long white setose,katepimeron long white setose;metanepisternum grey pubescent,asetose,metepimeron more-or-less flat,same colour as T1,grey pubescent,long white setose.

Leg:Light brown and brown,setation white setose,brown macrosetose;pro,mes,and met coxa lightly grey pubescent,long white setose;met trochanter setose medially;femur brown,met femur more-or-less cylindrical,only slightly wider than pro and mes femur,in distal half macrosetose,1anteroventral and1posteroventral row of macrosetae,posteroventrally long white,erect setose and setae arranged in distinct row;pro,mes,and met tibia straight,met tibia cylindrical,ventral keel absent,lateroposteriorly long white,erect setose and setae arranged in distinct row;pro and mes tarsomere1longer than tarsomere2,but less than combined length of tarsomeres2-3,met tarsomere1as long as combined length of tarsomeres2-3;pulvillus well-developed,as long as well-developed claw,and as wide as base of claw;empodium absent.

Wing:Length 13.8-15.2mm;hyaline throughout,veins light yellow,microtrichia absent;cells r1,r4,r5,m3,and cup closed;C terminates at junction with R1;R4 terminates in R1; R5terminates in R1;stump vein(R3)at base of R4 present,short not reaching R2;R4and R5widest apart medially; r–m distinct,R4+5 and M1 apart, connected by crossvein;M1 straight at r–m (not curving anteriorly),M1 (or M+M2)terminates in R1;CuA1 and CuA2 split proximally to m–cu (cell m narrow proximally);M3+CuA1do not terminate together in C;A1 undulating,cell a1 wide,A1 and wing margin further apart proximally than distally;alula well-developed,very large and partly overlapping with scutellum medially;haltere light brown.

Abdomen:Brown;setation comprised of dense long white setae,surface entirely smooth;T1-7brown;T1-7long white setose;T1apubescent,T2-7grey pubescent;S1-7brown;S1asetose,S2-7sparsely white setose;S predominantly apubescent;T2-4parallel-sided and not constricted waist-like;bullae on T2black,transversely elongate,surface entirely smooth,T2surface anterior to bullae smooth.

Terminalia(Figs1-3):Supra-hypandrial sclerite absent(see Remarks).

Female.

Thorax:Scutum predominantly grey pubescent,broad sublateral stripes(interrupted postsuturally)and narrow paramedial stripes(not reaching posterior margin)apubescent.Wing:Length15.0- 17.7mm.Abdomen:Scattered white setose;T1and anterior half of T2long white setose,remaining T short white setose;bullae on T2black,small and circular.Genitalia:6-7acanthophorite spines per plate.

Material examined: NAMIBIA: Erongo: 1♂ 1♀ Swakopmund, 5km E, 22°40'51"S 14°35'10"E,riverbed with Tamarix(Tamaricaceae), 4.ii.1978, O.Lomholdt (AAM-000865-AAM-000866, ZMUC) ; 1♂ 1♀ Swakop River mouth, 22°41'25"S 14°31'30"E,coastal and riverbed dunes, 8-9.ii.1974, L.Lyneborg (AAM-000859-AAM-000860, ZMUC) ; 1♂ 1♀ Swakopmund,S side Swakop River mouth, 22°41'33"S 14°31'37"E, 9m,sandy river bed and vegetated dunes,resting on sand, 3.ii.2012, T.Dikow (AAM-007366-AAM-007367, USNM) ; 1♂ Walvis Bay , 22°57'27"S 14°30'19"E, 24.i.1940 (holotype, SMNS) ; 1♀ Walvis Bay, 20.i.1939 (allotype, SMNS) ; 1♀ Sandwichhafen (= Sandwich Harbour ), 23°22'04"S 14°30'04"E, 19.i.1939 (AAM-003841, SMNS) .

Type locality and distribution:Walvis Bay(22°57'27"S 14°30'19"E),Namibia(Fig.43,GBIF resource#14003).Not known to occur in any biodiversity hotspot.

Remarks:When Hesse(1972)studied the specimens from the SMNS on which he based the new species description,he apparently did not study the female from Sandwichhafen also deposited in the SMNS.This specimen was studied by myself in October2010 during a visit to the SMNS.The absence of a supra-hypandrial sclerite in this species is quite surprising.It is possible that this sclerite has been fused with the dorso-lateral margin of the gonocoxite-hypandrial complex and therefore forming a “roof” closing this structure dorsally(Fig.1).

The species was recently collected at the Swakop River mouth by myself and observed to fly around the vegetated hummocks as shown in the habitat photograph in Fig.44.One specimen was collected resting on dead,grey vegetation low above the ground where it is well-camouflaged by its overall grey coloration(see Fig.13).