Silba lashker MacGowan and Razak

Macgowan, Iain, Razak, Nakeer, Rotheray, Graham E. & Ahmad, Irfan, 2012, A new species of fig-feeding Lonchaeidae (Diptera: Schizophora) from India and a checklist for the family in the Indian sub-continent, Zootaxa 3242, pp. 47-52 : 48-50

Silba lashker MacGowan and Razak sp. nov.

Description. Male: Head. Eyes bare. Frons matt black with light grey dusting, parallel sided, half width of eye. Frontal setulae short, approximately one fifth length of orbital setae. Interfrontal setulae equally short and sparse. Orbital plate subshining black, bare apart from orbital setae which are slightly shorter than the ocellar setae. Lunule, face and parafacials matt black with only slight silver dusting. Lunule bearing approximately eight short setulae. Genal setae short, anteriorly forming a single row of five along the oral margin, becoming stronger posteriorly, the basal of the five being the strongest on genae. Antennae entirelly black, 1st flagellomere 2.5 times longer than deep. Arista short plumed for a Silba species, with maximum extent of plumosity equal to half depth of the 1st flagellomere. Palpus entirelly black.

Thorax. Thoracic dorsum and sclerites subshining black, covered with light grey dusting, setulae covering dorsum very short, at maximum 0.25 length of orbital seta. Anepisternum with three strong setae anteriorly, three posteriorly. Other setulae on the sclerite rather sparse and short, no more than 0.25 of the setae. One propleural and one stigmatical seta. Prosternum with three weak seta on each side. Dorsal margin of katepisternum with one strong seta, a much shorter and finer seta situated anterior to it (in some paratypes this anterior seta is practically indistinguishable from other setulae on the sclerite), remainder of katepisternum bare apart from a scattering of five to seven short setulae on anterodorsal portion. Scutellar dorsum subshining, lightly grey dusted, slightly more brassy in colour than thoracic dorsum, with three short marginal setulae between lateral and apical setae, two tiny setulae present on the margin between apical setae. No setulae present anterior to lateral setae. Calypteres pale with pale margins and a short whitish fringe. Wings hyaline. Wing length 3.7 – 3.8mm. Legs entirelly black.

Male terminalia ( Figs. 1–3 ). Epandrium in ventral view slightly longer than wide with semi circular excavation anterodorsally, long setulae scattered posteroventrally. Cerci extending posteriorly, about half height of epandrium ( Fig. 1 ), not sclerotised, bearing short setulae on margins and apex. Surstyli not projecting beyond shell of epandrium although the upper surstylar teeth are just visible posteriorly. In ventral view surstyli slightly visible ventrally, their margins bearing a row of brownish setulae with the posterior 5 are strong and spine-like. A row of 7 relatively large sharp black teeth present on posterior lobe forming a curved row on inner surface of the surstyli, gradually decreasing in size ventrally. A pair of short setulae present just below bases of cerci. Aedeagus distinctive ( Fig. 3 ), a rather simple U-shape with two basal side arms, these gradually narrowing and pointed apically.

Female. Similar to male except with overall shorter setulae on the integument and wider frons 0.25 the width of an eye.

Female terminalia ( Fig 4 ). Aculeus gradually narrows towards apex, Apical segment dorsoventrally flattened, diamond shaped, basally embedded into the aculeus, with a pair of downward pointing short lateral setulae and two or three very short setulae lying anterior to these. Aculeus and apical segment noticeably golden-brown.

Description of third stage larva (N=2). Length 4.5-5mm; maximum width 0.68-0.83mm; maximum height 0.83-0.91mm. Truncate posteriorly, tapered anteriorly; dirty white except for black margins of posterior spiracular plates, red-brown margins of posterior spiracles and black sclerotised cephalopharyngeal skeleton; anterior spiracles consisting of eight respiratory bulbs arranged in a fan; posterior spiracular plates borne on short (0.05- 0.06mm) projections and sited on upper apical margin of anal segment; spiracular plates oval, separated by about two times the width of the spiracular plate; spiracular openings straight, about equidistant from each other and longer than wide (0.03mm long x 0.01mm); cuticular scar black and on inner, upper margin of plate; four groups of 3- 4, short, interspiracular setae present; oral lobes of pseudocephalon coated in cirri; integument without vestiture except the following: anterior margin of prothorax circumvented by numerous, short, straight or curved bars of upright microspicules generally orientated transversely across the segment; locomotory spicules on the anterior and posterior segmental boundaries of all abdominal segments consisting of 7 transverse rows of even sized spicules with 4 rows on the posterior margin and 3 on the anterior margin of each segment; mesothorax and metathorax without spicules or vestiture; anus surrounded by short spicules anteriorly and longer spicules posteriorly, laterally without surrounding spicules. Cephalopharyngeal skeleton ( Fig. 5 ) length 0.36mm; mandible with rectangular base, a curved apical hook and an oval-shaped dental sclerite sclerotised black; intermediate sclerite sclerotised black, bar-shaped; vertical plate and dorsal cornu sclerotised; ventral cornu brown, not as sclerotised; cibarial ridges present.

Differential diagnosis. Adult. The genus Silba is tropical and subtropical in distribution but in the northern part of this range there are species whose external characters vary increasingly from the “normal” Silba type. The species described here is a case in question. Although it does have the defining Silba character of a row of teeth on the posterior part of the surstyli there is only one, not two strong setae on the katepisternum and the plumosity of the arista is reduced, features which make it distinct from the majority of described species in this genus. The species described here clearly differs from the known fig feeding species S. adipata which has two seta on the katepisternum and a plumose arista. The male genitalia are also considerably different particularly in terms of the aedeagus which is relatively simple in S. adipata but bears a pair of strong basal processes in S. lashker .

Larvae. The larva is similar in overall appearance and basic features to other larvae of the Lonchaeidae . The extent of black sclerotisation of the cephalopharyngeal skeleton and lack of ornamentation, such as hooks, associated with the posterior spiracular plates is more similar to the genus Setisquamalonchaea than either Dasiops or Lonchaea although only one species of the former genus has been examined. The anterior margin of the prothorax with the distinctive ornamentation of short, transverse bars of microspicules may be a unique, defining feature of Silba as ornamentation of this kind is certainly absent in Lonchaea and apparently absent in Dasiops . However, the state of this character is unknown in other lonchaeid genera including Setisquamalonchaea .

Type material: Holotype 3. INDIA: Jammu and Kashmir, Srinagar, Hazratbal. 10.vii.2008, reared from Ficus carica collected in herbal garden of CCRUM (Central Council of Research in Unani Medicine), leg. N. Razak; paratypes: 2 3, 3 Ƥ with the same data as the holotype; 3 3, Ƥ, Chanapora, Srinagar 14.vii.2008. (types in Indian Agricultural Research Institute, Entomology section, New Delhi, PUSA, India; 3 and Ƥ paratypes in National Museums of Scotland, Edinburgh).

Etymology. From lashker , an Urdu noun meaning a group, referring to the group emergence of flies in the rearing cages.

Ecological information. Larvae were found at various sites in the Srinagar and Budgam Districts of the Kashmir valley infesting figs of Ficus carica . Intact fruits, both raw and ripe, which were heavily infested with tiny white larvae, were placed in rearing cages. The number of larvae emerging per fruit to pupate ranged between 3 and 10. In the CCRUM herbal garden samples 85-90% of the fruits were found to be infested. At other sites the level of infestation was somewhat lower ranging from 30-60%.

Figures

FIGURE 5. Silba lashker sp. nov. Third stage larva, head skeleton, lateral view, front end to the left, length 0.36 mm.

FIGURES 1 – 4. Silba lashker sp. nov. 1: Male epandrium and associated structures, lateral view; 2: Male epandrium and associated structures, ventral view, 3: Aedeagus lateral view. 4. Female aculeus dorsal view