Chen Ng(Pg61-69)
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- Bu səhifədəki naviqasiya:
- Notes about the gland-like structures in Stilpon
- Concluding remarks
- ACKNOWLEDGEMENTS
- LITERATURE CITED
342 Shamshev & Grootaert: A review of the genus Stilpon from the Oriental region Fig. 85. Hypothesised phylogenetic patterns of the species of Stilpon. Number refer to characters discussed under “Phylogenetic relationships within Stilpon”. Black dots = presumably non-homoplastic apomorphies; white dots = presumably homoplastic apomorphies. Strict consensus tree (Length = 32, C.I. = 0.75, R.I. = 0.90) of the three most parsimonious cladograms produced by analysis of the data matrix in Table 1.
343 THE RAFFLES BULLETIN OF ZOOLOGY 2004 on the male right cercus (character 19) and a feature of the female terminalia, namely the fusion of sternite 10 with anteroventral margin of tergite 8 (character 23). Additionally, in the S. nubilus complex the surstylar comb of the male left cercus (character 13) is absent. But the loss of the surstylar comb of the male terminalia is likely to be a homoplastic feature within the genus. We did not find any characters to support the monophyly of the S. graminum complex of the species sensu Cumming & Cooper (1992). In these species the upper lobe of the left surstylus of the male terminalia is completely divided. But, again, it is a homoplastic condition within Stilpon. The relationships of S. spinicercus and S. monospinatus, which were described in the present paper, are not clear. In
in S. nubilus. However, the female terminalia resembles those in S. graminum. S. spinicercus is the only known species of this clade which has the abdominal gland-like structures in the male. S. monospinatus is the most problematic species of this lineage on the whole. It was included into the S. graminum group primarily due to the presence of a single apical spine on the left cercus of the male terminalia. If such, than S. monospinatus might be most similar to the presumed basal condition of the S. graminum lineage. Unfortunately, the female is not found yet in this species. The presence of an erect ventral bristle (character 8) on the male fore tibia may suggest S. monospinatus is allied with S. spinicercus. The abdominal gland-like structures are absent in this species. The second lineage of the Stilpon clade with the shortened female terminalia includes several phenetically very similar and uniform species. The lineage is united on the bases of the completely yellow thorax (character 3) and minute or absent bristles in apical part of the left epandrial lamella of the male terminalia (character 11). The additional characters could be a complete division of the upper lobe of the left surstylus, the lack of the surstylar comb and the gland-like abdominal structures on the male abdomen. However, they appear to be homoplastic within the genus. We ascribed all species belonging to this lineage to as a separate species group within Stilpon (S. seeluang species group). The group is likely to constitute the sister relationships with the S. graminum species group. Within this newly recognised group S. laawae, S. crassinervis, S. nhamyaaw, and S. taksin are presumably closely related, sharing the greatly reduced male cerci (character 16) and 2 very long bristles on the male abdominal segment 8 (character 10). The relationships within this assemblage of the species are not resolved. The reduced inner vertical (character 2) and postpronotal (character 5) bristles may indicate the closer relationships between S. seeluang and the preceded complex of species. The presence of 2 spines on the male hind trochanter (character 7) may suggest some affinity of S. seeluang and S. isaanensis. Both species, especially S. isaanensis, appear to demonstrate the basal condition of the male terminalia for this group in the whole. One species included in S. seeluang group, namely S.
terminalia. However, these spines are unlikely to be homologous with those found in the species of the S.
(vs. apical in the S. graminum group). Additionally, the topography of the strong long bristles on the left cercus in S.
indicate that just these bristles are homologous with the spines in S. nhamyaaw. The relationships of two remaining species of this clade, S. paradoxus and S. yai are unclear. We have already discussed the possible affinities of these species in details (see “Phylogenetic relationships” under the respective descriptions). To summarise, S. paradoxus possesses many peculiar, autapomorphic features. It may represent a new, hitherto unknown group of the Stilpon species. S. yai was included in this clade provisionally since the female of this species has not been found yet. Some features may suggest these species to be closer related. However, this is speculation only and future discoveries of the genus are needed to clarify the relationships of these species. The assemblage of the species ascribed to as the S. divergens group is the most problematic unit within the genus. Cumming & Cooper (1992) recognised this group based on the plesiomorphic characters only: scutum entirely tomentose, rows of acrostichal setulae complete, setose left cercus of the male terminalia. Additionally, they noted that this group may be paraphyletic or even represent the stem group within the genus. Indeed, following this definition we should include the S. seeluang species group just into the S. divergens group. However, the S. seeluang group is quite distinctive lineage within Stilpon and it constitutes the sister relationships with S. graminum group. We consider that, preliminary, at least one apomorphic feature (long ventral bristle on the left cercus of the male terminalia, character 18) could support the monophyly of the S. divergens species group. The relationships within the S. divergens group and with other groups of Stilpon are not resolved at present. Within the group S. lekkwar and S. khorngkeun appear to be the sister species based on the presence of the apical spines on the middle lobe of the left surstylus (character 14). The precise recognition of the Stilpon sister group relationships within the Drapetini is likely to be especially important for the rigorous cladistic analysis of this unit. This also could be attributed to the S. varipes species group. The monophyly of the group is well supported by the lack of the scutal tomentum and incomplete acrostichal setulae. However, the relationships of the S. varipes group with other groups of Stilpon are not so evident. The main problem is likely to deal with our insufficient knowledge of the genus from the East Asia and western part of the North America.
In several Stilpon species studied from the Oriental region we found, for the first time in the genus, gland-like structures on the male abdomen. This character is a common and well known feature of some Drapetini genera allied to Stilpon, e.g. Elaphropeza, Drapetis, Crossopalpus, Dusmetina, 344 Shamshev & Grootaert: A review of the genus Stilpon from the Oriental region Isodrapetis, Nanodromia, and Austrodrapetis (Collin, 1961; Smith, 1964; Smith and Davies, 1965; Cumming & Cooper, 1992; Plant, 1999, Grootaert & Shamshev, 2003). These gland-like structures are considered to deal with epigamic behaviour (Smith and Davies, 1965). Stark (1990) suggested that the structures on the tergites were associated with a stridulatory organ in Elaphropeza. An electronmicroscopic study however showed the presence of glandular cells in Elaphropeza so that we suppose that the glands produce pheromones (Grootaert, unpublished observations). The structures found in Stilpon are very similar, in their external appearance, to those in Drapetis (A. Stark, personal communication). However, the fine details should be checked in the future. These structures were found in all species belonging to the S. divergens group (unclear in S. divergens),
structures are difficult to recognise without special preparation in the dry specimens and, especially, in specimens with shrunken abdomen. No any external features, that could indicate the presence of the gland-like structures, have been found. The gland-like structures usually look like simple, elongate, narrow, darkened spaces with a pilose vestiture. Rarely, they consist of three lobes (S. trilobatus and S. malayensis) or, sometimes, they are partly concealed by the corresponding tergites. In most species the gland-like structures occupy intersegmental spaces between tergites 4- 3 and 3-2 (S. khorngkeun, S. lek, S. malayensis, S. nhamdam, S. trilobatus), S. spinicercus – between tergites 3-2 and 2-1, in S. lekkwar – between tergites 5-4, 4-3 and 3-2. In S. paradoxus and S. yai they are indistinct and present between tergites 5-4, 4-3 and tergites 6-5, 5-4, 4-3, 3-2, respectively. The presence of the gland-like structures in Stilpon may support the hypothesis that the genus is closer related to Elaphropeza, Drapetis, Crossopalpus, Dusmetina, and Austrodrapetis (Cumming & Cooper, 1992; Grootaert, 1994) rather than to Chersodromia (Chvála, 1975). Within the genus these structures were apparently lost in the S. varipes, S.
groups.
Concluding remarks To conclude, the genus Stilpon is very well represented in the Oriental region. Seventeen species are now recognised from this region, which is more than from other biotic regions. The Oriental fauna of the genus demonstrates a great morphological diversity, including both species with many relatively plesiomorphic features and species possessing many apomorphic characters. These arguments may support the hypothesis that the early evolution of the genus occurred in the Oriental region (Cumming & Cooper, 1992). Four informal groups of species are now recognised within Stilpon. The S. graminum group includes species from the Oriental, Palaearctic, and Nearctic regions. The S. varipes and S.
Nearctic and Oriental regions, respectively. However, this pattern of distribution reflects our insufficient knowledge of the genus rather than the real relationships between the regions. Undoubtedly, our paper is only first step toward a detailed study of the genus Stilpon from the Oriental region. ACKNOWLEDGEMENTS This study was supported by a grant from the Belgian Federal Services for Scientific, Technical and Cultural Affairs. We thank the colleagues of Srinakharinwirot University in Bangkok for their help in the field, especially Dr. Verapong Kiatsoonthorn, Dr. La-aw Ampornpan and the technicians at Na Haeo Field Research Station, Mr. Sai Dan and Mr. Ai Patanajak. The second author thanks Prof. Dr. Peter Ng for the grant to study at the National University of Singapore as well as Mrs. Yang Chang Man, Dr. Darren Yeo Chong Yinn and Dr. Daiqin Li for their help in the field. P.G. also thanks Mr. J. Constant for his assistance in the field during May 2001 and 2003.
Chvála, M., 1975. The Tachydromiinae (Dipt. Empididae) of Fennoscandia and Denmark. Fauna entomologica Scandinavica,
Collin, J. E., 1961. Empididae. In British Flies. Vol. 6. Cambridge. 782 pp. Cumming, J. M. & B. E. Cooper, 1992. A revision of the Nearctic species of the Tachydromiinae fly genus Stilpon Loew (Diptera: Empidoidea). The Canadian entomologist, 124: 951-98. Dahl, F., 1909. Die Gattung Limosina und die biocönotische Forschung. Sitzungsberichte der Gesellschaft naturforschender Freunde zu Berlin, 1909: 360-377. Fallén, C. F., 1915. Empididae Sveciae. Lundae. 16 pp. Goloboff, P. A., 1999. – NONA, version 2. Program and
Grootaert, P., 1994. Two new genera of empidoid flies (Diptera, Empidoidea, Hybotidae, Tachydromiinae) from Melanesia.
Grootaert, P. & I. V. Shamshev, 2003 (2004). New species of the genus Nanodromia Grootaert (Diptera: Empidoidea, Hybotidae) from Thailand and Singapore. The Natural History Journal of Chulalongkorn University, 3(2): 41-52. Janzen, J.-W., 2002. Arthropods in Baltic Amber. 167 pp, Germany: Ampyx-Verlag, Halle (Saale). Loew, H., 1859. Neue Beiträge zur Kenntniss der Dipteren. Sechster Beitrag. Programm der Königlichen Realschule zu Meseritz,
Loew, H., 1864. Ueber die schlesischen Arten der Gattungen Tachypeza Meig. (Tachypeza, Tachista, Dysaletria) und Microphorus Macq. (Trichina und Microphorus). Zeitschrift für Entomologie, Breslau, 14: 1-50. McAlpine, J. F., 1981. Morphology and terminology – Adults. Pp. 9-63. In: McAlpine, J. F. et al. (eds.), Manual of Nearctic
Monograph 27, 674 pp; Ottawa. 345 THE RAFFLES BULLETIN OF ZOOLOGY 2004 Meigen, J. W., 1830. Systematische Beschreibung der bekannten europäischen zweiflügeligen Insekten. Vol. 6. Hamm. 401 pp. Meunier, F., 1908. Monographie des Empidae de l’ambre de la Baltique et catalogue bibliographique complet sur les Diptères fossiles de cette résine. Annales des Sciences naturelles (Zoologie), (ser. 9) 7: 81-135, pl. 3-12. Nixon, K., 1999. WINCLADA, ver. 0.9.9beta. Program and documentation in cladistics.com. New York: Ithaca. Perris, E., 1852. Seconde excursion dans les Grandes-Landes. Annales de la Société Linnéenne de Lyon, 1850/1852: 145-216. Plant, A., 1999. New species of Isodrapetis Collin, 1928 (Diptera, Empidoidea, Hybotidae) with a detailed diagnosis of the genus.
Séguy, E., 1950. Un nouveau genre de Corynétine du Midi de la France (Dipt., Empididae). Vie et milieu, 1: 83-87. Sinclair, B.J., 2000. Morphology and terminology of Diptera male terminalia. Pp. 53-74. In: Papp, L. & B. Darvas (eds.),
Budapest: Science Herald. Smith, K. G. V., 1964. A remarkable new genus and two new species of Empididae (Tachydromiinae, Drapetini) from the Cook Islands. Pacific Insects, 6: 247-251. Smith, K. G. V., 1969. The Empididae of southern Africa (Diptera). Annals of the Natal Museum, 19: 1-342. Smith, K. G. V. & R. G. Davies, 1965. Gland-like abdominal structures of possible epigamic function in the Diptera. Nature,
Stark, A., 1990. Interpretation abdominaler und tibialer Strukturen bei Dipteren der Gattung Elaphropeza (Hybotidae, Empidoidea) als Stridulationsapparat. Zoologisher Anzeiger, 224: 211-224. Stuckenberg, B. R., 1999. Antennal evolution in the Brachycera (Diptera), with a reassessment of terminology relating to the flagellum. Studia dipterologica, 6: 33-48. Appendix. 1. Data matrix of character states for the phylogenetic analysis of species of Stilpon. 0, plesiomorphic state; 1, apomorphic state; ?, missing data. Characters are coded as binary, except character 17 (vestiture of the male left cercus) which was treated as an unordered multistate character. Characters 12345678911111111112222 01234567890123 Outgroup
00000000000000000000000 S. varipes 10010100100000000001000 S. chillcotti 10010100100000000001000 S. graminum 10000000100100102001110 S. nubilus 10000000100010102011111 S. subnubilus 10000000100010102011111 S. spinicercus 10000001000100102001100 S. monospinatus 10000001100100001001??? S. seeluang 11101010101110000001100 S. isaanensis 10100010101110000001100 S. laawae 11101000111110010001100 S. crassinervis 11101000111110010001??? S. nhamyaaw 11101000111110010001100 S. taksin 11101000111110010001100 S. lek 10000000000000000101000 S. lekkwar 10000000000001000101000 S. khorngkeun 10000000000001000101??? S. nhamdam 10000000000000000101000 S. trilobatus 10000000000000000101000 S. malayensis 10000000000000000101??? S. divergens 10000000?00000000101000 S. paradoxus 10000000000100000001100 S. yai 10000000000100000001??? 346 Shamshev & Grootaert: A review of the genus Stilpon from the Oriental region Appendix 2. List of characters for the analysis of the phylogenetic patterns within Stilpon. 1. Frons: triangular (0), linear (1). 2. Inner vertical bristles: long (0), hardly prominent (1). 3. Thorax colour: black (0), completely yellow (1). 4. Scutum vestiture: entirely tomentose (0), lacking tomentum (1). 5. Postpronotal bristle: long (0), hardly prominent (1). 6. Acrostichal setulae: complete (0), incomplete or absent (1). 7. Male hind trochanter: lacking spinules (0), with 2 spinules (1). 8. Erect ventral bristle on male fore tibia: absent (0), present (1). 9. Abdominal gland-like structures: present (0), absent (1). 10. Male segment 8: with moderately long bristles (0), with at least 2 very long bristles (1). 11. Bristle(s) in apical part of left epandrial lamella: long (0), hardly prominent or absent (1). 12. Upper lobe of left surstylus: undivided (0), partly or completely divided into 2 parts (1). 13. Surstylar comb: present (0), absent (1). 14. Apical spines on mid lobe of the left surstylus: absent (0), present (1). 15. Right surstylus: not prolonged apically (0), prolonged apically (1). 16. Male cerci: well prominent (0), reduced (1). 17. Apical spine(s) on the male left cercus: absent (0), 1 spine (1), 2-3 spines (2). 18. Long ventral bristle in basal part of the left cercus: absent (0), present (1). 19. Apical spines on the right cercus: absent (0), present (1). 20. Ejaculatory apodeme: paired (0), single (1). 21. Female terminalia: elongate (0), shortened (1). 22. Female cercus: elongate oval (0), broad oval (1). 23. Sternite 10 of female terminalia: not fused with ventroapical margin of tergite 8 (0), fused with ventroapical margin of tergite 8 (1). Yüklə 335,61 Kb. Dostları ilə paylaş:
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