Paramimegralla Hennig

Marshall, Stephen A., 2017, Micropezidae (Insecta, Diptera, Acalyptratae) of Madagascar and a revision of the genus Paramimegralla Hennig, Zootaxa 4290 (2), pp. 244-280 : 248-250

Revision of Paramimegralla Hennig

Paramimegralla Hennig 1937

Paramimegralla Hennig 1937: 46 . Type species Paramimegralla madagascariensis Hennig by original designation. Stiltissima Barraclough 1991 , New Synonym

Rainieria in part, sensu Barraclough not Rondani

Generic diagnosis. Size 10̄ 18 mm, variable within species. Colour ranging from pale brown to shining black, leg colour variable between species and between sexes. Head chaetotaxy including inner and outer vertical, postocellar and 1̄3 pairs of fronto-orbital setae (usually 3 but one or both frontal setae sometimes absent). Frontal vitta broad and weakly differentiated, usually extending from postocellar setae to anterior margin of frons but often strongly tapered anteriorly or posteriorly (posterior part obsolete in longicephala ). Ocelli usually inserted near midpoint between postocellar setae and anterior margin of frons, rarely closer to anterior margin; frons length anterior to ocelli never more than 2.5X the length of the frons posterior to ocelli. Palpus broad, parallel-sided. Pedicel strongly notched dorsally, with 2̄3 long marginal ventral setae; arista bare, arising dorsobasally. Clypeus variably developed, angled forward. Upper parafacial expanded, sometimes strongly. Notum tapered and moderately to strongly elevated anteriorly, usually densely microsetulose. One dorsocentral, 2 notopleural, 1 supralar, 1 postalar, and one scutellar seta. Proepisternum with minute to very long setae on ventral margin, proepimeron enlarged, ventrally indistinguishable from mesosternum but dorsally separated from anterior anepisternum by a distinct suture. Katepisternum with a double vertical row of posterior setae. Wing variously pigmented, anal cell long, posterior margin longer than A1+CuA2, distal angle usually acute but less extended than most Taeniapterini, most species with a distal angle of around 45% (about 70 ° in quadrifasciata ). Base of wing without costagial or other outstanding setae; axillary cord with axillary fascicle made up of relatively long, loosely packed setae. Abdomen with T1̄2 about twice as long as T3, posterior margin of T1 usually elevated. Pleural membrane variously pigmented, usually with extensive black areas, males of some species with a prominent pleural sac on segment three. Male genital fork (sternite 5) variously developed, arms very short in madagascariensis and zinzala , each arm basally forked in anchivitta , campanula and longicephala . Distiphallus diagnostic for species but variable at the generic level, with the distal distiphallus long and thin, short with a modified tip, or entirely absent. Ejaculatory apodeme usually similar in size to epandrium, but sometimes with a greatly enlarged blade (as in P. sulcata , Fig. 71 ) and sometimes greatly reduced (as in the P. steineri and P. stiltodes , Figs. 57 , 65 ). Females with oviscape less than half as long as remainder of abdomen, spermathecae including a single slightly to greatly reduced spermatheca on a separate duct and paired spermathecae on a thick duct that branches into variably shaped and swollen stems basal to the spermathecae. Ventral receptacle strongly developed to greatly reduced.

Comments. The generic diagnosis of Paramimegralla above differs in several respects from the generic redescription provided by Barraclough (1992). Species with relatively long legs and without frontal setae were excluded by Barraclough (and treated as Stiltissima ), as were species with long propleural setae (which he treated as Rainieria ). Furthermore, Barraclough suggested that flattened tarsomeres one and two of the foreleg were likely to be a strong apomorphy for the genus, even though he only had intact males of one species on which to base this suggestion. As it turns out, the flattened and expanded tarsomere one of the male foreleg of P. nigra ( P. stuckenbergi of Barraclough) appears to be autapomorphic for that species, although the male fore tarsus of P. verticalis (probably " Rainieria nsp" of Barraclough) is also strongly modified ( Fig. 91 ).

Relationships and distribution. A concept of Paramimegralla including Stiltissima and the Malagasy specimens treated as Rainieria by Barraclough (1991) is supported by synapomorphies placing those species in well–defined species groups within Paramimegralla . The " Stiltissima " species form a monophyletic group with P. vadoni and P. stiltoides . This clade is characterized by a truncated distiphallus ending in the distal bulb, without the normal distal section, and by a greatly reduced ejaculatory apodeme (similar character states occur in P. nigra ). Furthermore, males of " Stiltissima ", P. vadoni and P. stiltissima have a prominent pleural sack on abdominal segment three ( Figs 58 , 86 ). Many male Taeniapterinae have a pleural sac on segment two and some Afrotropical species ( Aristobatina Verbeke ) have a pleural sac on segment four, but a pleural sac on segment three is unusual and a probable synapomorphy for the Paramimegralla vadoni – stiltissima clade. The pleural sac (an outpocketing of the male pleuron) is difficult to assess on dried specimens, and could also occur on P. stiltoides . Other species for which photographs of live males are available lack a homologous structure, although P. nigra males have a ventrally swollen abdominal segment four, unlike other species. These characters provide strong evidence that P. vadoni , P. stiltodes and the former Stiltissima form a clade, and suggest that P. nigra is the sister group to that clade.

Malagasy micropezids with long proepisternal setae were considered to belong to an undescribed species of Rainieria by Barraclough (1991), but species with that character ( anchivitta , verticalis and sulcata ) appear to fall into two species groups, with verticalis more closely related to P. zarpa and P. campana , which in turn seem to be closely related and are characterized by a distal swelling ("glans") on the distal distiphallus. Rainieria is a poorly defined genus in need of revision, but the type clade (the type species and its close relatives) differs widely from Paramimegralla in significant characters such as a strong inclinate costagial seta, sulcate hind tibia, anteriorly tapered frontal vitta and a very short anal cell. Thus, morphological characters do not seem to suggest a close relationship between any Malagasy species and Rainieria .

Paramimegralla madagascariensis and P. zinzala are clearly sister species, with many close similarities in wing pigmentation and male terminalia, such as the extremely short arms of the genital fork. External characters suggest that P. luteoscapus belongs in the same clade as P. madagascariensis and P. zinzala although this species remains unknown from males.

Paramimegralla is known only from Madagascar, and for the most part known only from a few well–collected humid forest localities. Most Paramimegralla species are known from either or both Ranomafana National Park and the area around Andasibe (Perinet), and the majority are known only from the Torotorofotsy reserve 22 km from Andasibe , and/or the Sahamalaotra forest at Ranomafana. This apparent concentration of diversity becomes all the more remarkable when examined in detail. For example, it was very dry for most of my brief stay at Ranomafana, and almost no Micropezidae were collected until rain during the night of Oct. 15 led to about three hours of very productive collecting in Sahamalaotra the next morning. Ten of the 18 known Paramimegralla species were collected during that period, including six new species (of which three remain known only from that collection). Collections made at Andasibe (Torotorofotsy) a few days later yielded eight species (of which two remain known only from those collections). Without further material from a wider range of localities it is hard to make sense of this apparent concentration of species in a couple of forest reserves, but it seems very likely that many more species remain to be discovered elsewhere in the country or even at these two relatively well–collected reserves. Four species described from those two reserves remain known only from single specimens, and several species remain known only from a single sex, posing an intriguing challenge for future students of Malagasy Micropezidae . Three species are known only from the northern/northwestern tip of the island, and two of these ( P. volcanica and P. madagascariensis ) are clearly sister taxa to species from the eastern forests at Ranomofana and/or Andasibe ( P. steineri and P. zinzala , respectively).

Descriptions of all known Paramimegralla species follow, starting with the type species and following in alphabetical order.

Figures

FIGURES 69 – 75. Paramimegralla sulCata sp. nov., 69. Holotype female, dorsolateral; 70. Spermathecae and associated structures, 71. Male terminalia, left lateral; 72. Male S 5 with genital fork; 73. Living female, left lateral, Ranomafana; 74. Basal part of phallus; 75. Basal half of abdomen to show pleural membrane.

FIGURES 53 – 60. Paramimegralla steineri (Barraclough). 53. Spermathecae and associated structures, dorsolateral; 54. Spermathecae and associated structures, lateral to show ventral receptacle; 55. Male S 5 with genital fork; 56. Male terminalia, ventral; 57. Male terminalia, left lateral; 58. Male with pleural sac everted, left lateral; 59. Male with pleural sac retracted, left anterolateral; 60. Female.

FIGURES 61 – 68. Paramimegralla stiltOides sp. nov., 61. Male, left lateral; 62. Male abdomen, right lateral; 31. Male S 5 with genital fork; 64. Male, dorsolateral; 65. Male terminalia, left lateral; 66. Head, dorsolateral; 67. Paired spermathecae; 68. Spermathecae and associated structures.

FIGURES 88 – 96. Paramimegralla vertiCalis sp. nov., 88. Head dorsal; 89. Head and anterior thorax anterolateral (arrow points to proepisternal setae); 90. Male, Andasibe; 91. Male fore tarsus and tibia; 92. Terminalia, ventral, dry specimen; 93. Male sternite 5 showing genital fork; 94, Male terminalia, left lateral, detail; 95. Spermatheca and associated structures, lateral; 96. Male terminalia, left lateral. Abbreviations: aa, phallapodeme; b, basiphallus; bd, basal distiphallus; e, epandrium; ea, ejaculatory apodeme; h, hypandrium; pb, phallic bulb; pg, postgonite.

FIGURES 83 – 87. Paramimegralla vadOni Verbeke. 83. Male feeding on dung bait, Ranomafana; 84. Male terminalia, left lateral; 85. Abdomen segments 4 ‾ 7, lateral; 86. Male, left lateral, to show everted pleural sac; 87. Spermathecae and associated structures (bursa copulatrix detached and in lateral view).