Dasyrhicnoessa tripunctata

Munari, Lorenzo, 2015, Taxonomic and distributional notes on two species groups of the genus Dasyrhicnoessa Hendel (Diptera: Canacidae: Tethininae), Zootaxa 3920 (4), pp. 545-554 : 547-550

The Dasyrhicnoessa tripunctata group

This species group comprises four strikingly similar and closely related species, which are distinguished from each other exclusively by the genitalic characters of the male. The species of this group have been recorded from western India to the western Pacific coasts. However, a single female specimen from the United Arab Emirates ( Munari, 2010b) was tentatively recorded as the western Pacific species D. tripunctata . The identification of this female is doubtful, being based mainly on the colour of the head. For a more detailed discussion, the reader is referred to Munari (2010b), who also stated “Although unwillingly, I am unable to give a different attribution to this female specimen as no male has been found in the material examined”. I think now that this specimen is not D. tripunctata and perhaps belongs to an undescribed species. However, it will remain only tentatively identified until new material from the UAE is available for examination.

The four following species are referred to the Dasyrhicnoessa tripunctata group:

adelpha Munari, 2005 (figs. 4─6)

Dasyrhicnoessa adelpha Munari, 2005: 589 [ India. Goa, Panjim, beach]; the holotype ♂ and four paratypes (♂♀) are deposited in TAU, three other paratypes (♂♀) are in LMC. The paratypes bear the following locality label: “ India: Goa, Ribander, 5 km E, Panjim, mangrove, 2.xii.2002, A. Freidberg”.

Distribution. Oriental: India ( Goa).

Remarks. The sites where this species was collected represent the sole records of this genus from the Indian subcontinent. Indeed, this huge area represents to date a wide biogeographical gap for this genus, as well as for the entire family, which is very poorly reported from India in the literature.

This species is strikingly similar and closely related to the other species of the tripunctata group. It differs from these species mainly by the different outlines in lateral view of both the anterior and posterior surstyli (figs. 4─6). Munari (2005) also stated that it is characterized by having frons and gena distinctly darker than in D. tripunctata . However, further studies, including the descriptions of two other new species (see below), have proved these character states are not consistent, and fall within the range of variation seen within this group. Therefore, the most reliable method of distinguishing this species from the others that have spotted abdominal tergites is to examine the structures of the male terminalia (see characters given in the key).

celata Munari, 2010 (figs. 7─10)

Dasyrhicnoessa celata Munari, 2010a: 61 [Bismarck Islands. Dyaul Island: Sumuna]; the holotype ♂ is deposited in ZMUC, two paratypes ♂♂ (same data as holotype) are in ZMUC and in LMC, respectively.

Distribution. Australasian/Oceanian: Bismarck Islands.

Remarks. This species occurs sympatrically with D. tripunctata , and in all probability it is a thalassobiont species strictly associated to mangrove swamps. D. celata was discovered by chance after examining the male terminalia of all specimens of the D. tripunctata group from Dyaul Island. The surstyli of these two species are always slightly exposed and the peculiar posterior surstylus of D. celata was, therefore, immediately noticed and the type specimens segregated. Anterior and posterior surstyli are very distinctive for their peculiar shape (figs. 7─10), as indicated in the key provided herein.

malayana Munari, 2014 (figs. 2, 3)

Dasyrhicnoessa malayana Munari, 2014: 284 [ Malaysia. Malay Peninsula: Negeri Sembilan, Port Dickson, 2°31’N, 101°48’E]; the holotype ♂ is deposited in NHM.

Distribution. Oriental: Malaysia (Negeri Sembilan).

Remarks. Dasyrhicnoessa malayana is known only from the holotype. The canacid fauna, the subfamily Tethininae in particular, is very poorly known from the Malay Peninsula. Indeed, the citations from this peninsula are scarce and fragmentary. Therefore, the discovery of this species is of particular importance to better understand the distribution of this species group. As indicated in the key provided herein, D. malayana is characterized mainly by the large, two-pointed anterior surstylus, and by the posterior surstylus which is distinctly truncated apically (fig. 2). However, the most peculiar feature is the conspicuous, transverse, narrow thickening on ventral margin of the epandrium (figs. 2, 3), this character being unique among the species of the entire subfamily. It would be important to get additional males in order to corroborate this peculiarity, which was noticed on a single specimen only.

tripunctata Sasakawa, 1974 (figs. 1, 11─14)

Dasyrhicnoessa tripunctata Sasakawa, 1974: 5 [ Philippines. Palawan: Tinabog (3 km NE)]; the holotype ♂ is deposited in BPBM (10355) along with three paratypes from the following localities: Philippines, Culion Island, 6 km W of Culion, (2 ♀♀); Philippines, Palawan, Tarumpitao Point, (1♂).

Distribution. Australasian/Oceanian: Australia (Queensland), Bismarck Islands (Dyaul, Mussau), Caroline Islands (Kosrae, Palau, Pohnpei), Mariana Islands ( Guam), Papua New Guinea. Oriental: Japan (Ryukyus), Malaysia (Sabah, Sarawak), Philippines (Balabac, Culion, Palawan, Tawi-Tawi). Palaearctic:? United Arab Emirates.

Remarks. Since the Dasyrhicnoessa tripunctata group consists of externally quite similar, but genitalically very distinct species, some former citations of this species from the West Pacific islands need verification based on examination of male terminalia. Apart from the doubtful citation from the United Arab Emirates (see above), the westernmost record of this species is from the Malaysian state of Sarawak.