Diptera: Sphaeroceridae: Limosininae)

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Center for Systematic Entomology, Gainesville, Insecta Mundi Florida June 1997 A revision of the Sclerocoelus galapagensis group (Diptera: Sphaeroceridae: Limosininae) S. A. Marshall Department of Environmental Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada Follow this and additional works at: https://digitalcommons.unl.edu/insectamundi Part of the Entomology Commons Marshall, S. A., "A revision of the Sclerocoelus galapagensis group (Diptera: Sphaeroceridae: Limosininae)" (1997). Insecta Mundi. 260. https://digitalcommons.unl.edu/insectamundi/260 This Article is brought to you for free and open access by the Center for Systematic Entomology, Gainesville, Florida at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Insecta Mundi by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. INSECTA MUNDI, Vol. 11, No. 2, June, 1997 97 A revision of the Sclerocoelus galapagensis group (Diptera: Sphaeroceridae: Limosininae) S. A. Marshall Department of Environmental Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada. Abstract: The Sclerocoelus gcilapage~lsisgroup is defined and revised, including the description of S. galapage~~sisnew species from the Galapagos Islands; S. cariberlsisnew species from the Caribbeanand adjacent areas; S. brasilertsisnew species from Brazil, Ecuador, Colombia, ancl Panama; S. ltetttorrl~oidalisnew species from Ecuador and Venezuela; and S. andensis new species from Argentina, Bolivia, and Venezuela. The south Atlantic species Sclerocoelus sl~bbreuipert~iis(Frey), new combination, is rctlescribed as a member of the S. galapage~tsisgroup, and is considered the sister species to the rest of the species group. A lcey to species, character matrix, ant1 claclogram are provided. Introduction Diagnosis of the genus Sclerocoelr~s:Mem- The genus Sclerocoelus Marshall is abundant bers of the genus Sclerocoelzrs can be recognized by in the New \Vorltl, with over 40 species clistributed thc combination of a very broad alula, an enlarged from Canada t,o Argent,ina, ant1 with one species, intra-alar bristle just anterior to the pre~cut~ellar Sclerocoelz~ss~rDbrevil)e~t,r~is (l?rey) from the south dorsocentral bristle, a very broad lunule and char- Atlantic. The latter species is a member of the acteristic tibia1 chaetotaxy including a micl ventral distinctive Sclerocoelu,sgalc~~)ager~sisgroup, and is bristle only in the female. Characteristics of the here redescribcd from Tristan (la Cunha. The S. male genitalia, especially the complex subcerci ancl gal~pager~sisgroup also includes five other new genital pouch, are definingfor the genus (Marshall, species from the Galapagos Islands, Mexico, the 1995). Caribbean, Central America, and South America Diagnosis of the Sclerocoelus galapagen- (M~I)). sis group: All mcmbcrs of the species group have Most Sclerocoell~sare a~sociat~cdwith wet, cle- strongly developed male perianal pacls, character- caying vegetation in cloucl forests, where they are istically shal)ccl surstyli, and one (or rarely 2) stout often collected in large numbers by sweeping a net apical bristle on each female cercus. All Neotropi- ovcr moist dead leaves. The species group revised cal specics have setae on the membrane flanking here, the S.gnlapcrg.ert.sis gronl), is the most clistinc- the prosternum. tive and easily diagnosecl group of Sclerocoelus. All Description of the Sclerocoelusgalapagen- species in the group can easily be distinguished sis group: Dark, heavily pollinose limosinines, from congeners by the conspicuous, sclerotized 2.0-3.0mm, usually ca. 2.5mm. Interfrontal area male perianal patls or by the spinose apical bristles tapcred, width at top equal to height; 3 equal of the female cerci. They are also generally larger interfrontal bristles. Lunule prominent, broadly than congeners ancl, as outlinecl in the diagnosis rounded. Fore cosa with 3-4 short, stout medial below, form a clearly monophyletic group charac- greapical bristles. Acrostichal bristles in 8 rows terized by other striking apomor1)hic characters. between anterior dorsocentrals; ~rescutellaracros- Other than the G species considered here, the tichal bristle and posterior intra-alar bristle tivice only described species of Sc1erocoelu.s are the wide- as long as anterior dorsocentral bristle; anterior spread, Nearctk, type spccies, S. sordipes (Adams), dorsocentral bristle slightly longer than acrostichal and the Ncot;ropical species S. plzi.~rsisela(Duda) setulae. Scutellum 1.3-1.5X as wide as long, four and S. regu,laris (Malloch). apical bristles 1.8-2.OX as long as scu tellum. Dorsal surface of mid tibia with 2 large anterodorsal bris- Sclerocoelus Marshall tles and 1 small posteroclorsal bristle proximally, Sclerococlrss Marshall, 1995: 283. Type species Lir~tosi~~aposterodorsal bristle midway between anterodor- sordipes Aclai~ls1904 sals; 2 anteroclorsal bristles elistally, the lower one twice as long as the upper; 1 very large posteroclor- 9 8 Volunle 11, No. 2, June, 1997, INSECTA MUNDI sal distal bristle; 1 very small distal dorsal bristle at acters (18,19). The short, brown wings of gal- level of upper anterodorsal. Mid tibia of female upczger~sisare extremely similar to those of subbre- with a midventral bristle; ventral surface of male viper~r~is;however, shortening and darkening of mid tibia with a patch of short, stout bristles distal- wings is common in insular sphaerocericls and ly; mid tibia of both sexes with a strong apicoventral these characters are therefore considered especial- and weaker posteroventral and anteroventral api- ly subject to homoplasy. The third cladogram cal bristles. Miclfemur with short, stout anteroven- treatsgalapagerzsis as the sister group to the rest of tral and posteroventral bristles basally; mid basi- the genus, and links the Atlantic subbreuiper~r~isto tarsus with an enlargecl ventral bristle in basal mainland Neotropical and Caribbean species on the half. Wing with seconcl and third costal sectors basis of two characters of equivocal polarity (6,21). equal; R,,, sinuate, strongly curved up to costa. Character 21, the presence of a single stout apical Abdomen: Syntergite 1+2 with broad, short, bristle at the apex of the female cercus, is probably anterior pale area with a narrow posterior exten- a synapomorphy for the whole species group and is sion. Sinistral flange of synsternite 6+7 short, reversedin galapager~sisby the enlargement of the weakly developed; synst,ernite completely separat- inner preapical cercal bristle found in all members ed from sternite 8. Inner ventral corners of epan- of the species group. driurn widely separated, forming narrow, truncate The relationships between the remaining four lobes. Sternite 10 (subepandrial sclerite) com~lete species, all found in mainland South America and medially. Subcercus complex, with an outer (up- the Caribbean basin, are well supported. Sclerocoe- per) part usually projecting posteriorly into the lus brasilerlsis is the most plesiomorphic of the perianal pad and anteriorly to the posterior surst- mainlancl spccies, wit,h superficial similarities to ylar-cpanclrial junction, ancl an inner (lower) part the island endemics. Sclerocoelus hrasiler~sisis often with a long posterior arm; junction of inner treated as the sister group to the otther mainland and outer parts of subcercus with posterior bristles; and Caribbean species on the basis of six weak left ancl right subcerci meeting or almost meeting synapomorphies (7,9,13,14,20,22), tvhich are not near post,eromeclialpart of sternite 10 (subepandri- conflicted elsewhere on the cladogram. The mono- a1 sclerite). Distiphallus short, broad, dorsoven- phyly of a group containing the remaining three trally flattened, with broad, laterally-directed bas- species in the group (cariber~sis,ar~der~sis, Iternor- al sclerites, a basal ring, ancl a dist,al part compris- rhoidalis) is much more strongly supported. Rela- ing two curved lateral sclerites and a medial scler- tive to ot,her Sclerocoelus, members of this group ite which is usually distally bifid. Three spermath- seem to be characterized by progressive rccluction ecae, single one largest; s.ivollen apically with a of the complicate0 set of genital pouch sclerites shallow invagination; ducts short, inserted near (Character 1). Most members of the genus have an invagination; surface striate. apparently homologous series of sclerit,esincluding 4 or 5 separat,e sclerit,es bet,ween tjhe left side of Phylogeny of the Sclerocoell~sgalapagensis synsternit,e 6+7 and the spiracular sclerite on the species group right side of the abdomen. In the basal lineages of the galapcger~sisspecies group, 3 of these sclerites Analysis of a matrix of 22 characters, using are clearly visible, and 2 (sclerites C and D) are Hennig 86, yielclecl three equally parsimonious separate as in other Sclerocoelus. These sclerites cladograms (consistency index 82, reten tion index disappear in the highly distinctive Neotropical clacle 87, length 35) which differed only in the placement including cariher~sis,ar~der~sis, and hernorrhoida- of the two island endemics, the Atlantic subbreui- lis, and are replaced with a deep, evenly sclcrotized per~r~isancl the Pacific galapager~sis. I prefer the pouch. This group is also characterised by a num- cla(1ogram treating si~bbreviper~r~isas the sister ber of other unique synapomorphies of the male group to the rest of the genus, and placing gal-

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