Dasyrhicnoessa vockerothi Hardy & Delfinado, 1980

Munari, Lorenzo, Kirk-Spriggs, Ashley H. & Mcgregor, Gillian K., 2020, The beach flies of the Mascarene Islands (Diptera: Canacidae: Tethininae), Zootaxa 4853 (2), pp. 183-198 : 193

Dasyrhicnoessa vockerothi Hardy & Delfinado, 1980

Figs 12 , 17 , 28 , 33 .

Distribution. Afrotropical: Mascarenes ( Mauritius *, Rodrigues *), Seychelles (Aldabra, Astove, Mahé). Australasian/Oceanian: Australia (New South Wales, Northern Territory, Queensland), Bismarck Islands (Dyaul), Caroline Islands ( Truk, Palau), Hawaii (Hawaii, Hilo, Kauai, Maui, Molokai, Oahu), Kiribati, Mariana Islands ( Guam, Saipan), Marshall Islands,? New Caledonia, Papua New Guinea, Wake Island. Oriental: Cocos Islands, Japan (Ryukyu Islands), Malaysia (Penang, Sarawak, Selangor), Philippines, Singapore, Sri Lanka.

Material examined (all “A.H. Kirk-Spriggs & B.S. Muller, sweeping intertidal zone and coastal vegetation”, unless otherwise stated). Mauritius: 2♂, 1♀, Flacq, Poste Lafayette , 20°07′02″S, 57°45′05″E, 1–3 m, 30.i.2018 (1♂ deposited LMC) ; 1♀ (cf.), Pamplemousses, Le Goulet , 20°06′14″S, 57°31′02″E, 1–3 m, 30.i.2018 ; 1♂, 2♀, Pamplemousses, Trou aux Biches , 20°02′36″S, 57°32′14″E, 1–3 m, 29–30.i.2018 ; 1♀, Savanne, Bel Ombre , 20°29′32″S, 57°22′42″E, 1–3 m, 26.i.2018 ; 1♂, Savanne, Riambel , 20°31′09″S, 57°30′25″E, 1–3 m, 26.i.2018 ; 1♂, 1♀, Savanne, Rivière des Galets , 20°30′04″S, 57°26′52″E, 1–3 m, 26.i.2018 . Rodrigues: 2♂, 1♀, Anse Ally , 19°41′42″S, 63°29′48″E, 1–3 m, 10.ii.2018 ; 1♂, 2♀, Anse aux Anglais , 19°40′15″S, 63°26′19″E, 1–3 m, 10.ii.2018 (1♂ deposited LMC) ; 1♂, Anse Mourouk , 19°44′23″S, 63°27′53″E, 1–3 m, 10.ii.2018 (deposited LMC) ; 3♀ (cf.), Baie du Nord , 19°42′33″S, 63°22′20″E, 1–3 m, 9.ii.2018 (1♀ deposited LMC) ; 2♀, Île Michel , 19°44′43″S, 63°24′13″E, 1–3 m, 10.ii.2018 ; 1♂, Plaine Mapou , 19°44′52″S, 63°20′21″E, 1–3 m, 9.ii.2018 ; 3♂, Rivière Banane , 19°40′37″S, 63°28′30″E, 1–3 m, 10.ii.2018 (all deposited BMSA, unless otherwise stated).

Comments: Usually smaller than its congener, D. insularis , with which it is easily confused by the moderate to wide coverage of yellow on the mesonotum, which in some cases, may be uniformly pale grey, with light yellowish nuances. Specimens from different Pacific locations often exhibit the same range of variation, with a few even exhibiting a uniformly grey to brownish mesonotum. The posteroventral armature of spine-like setae on the male mid femur is also similar in the two species and most specimens have this armature similar to that of D. insularis . As well as their relative sizes, the two species are unequivocally characterised by the morphology of the male terminalia, especially the shape of the surstylus ( Figs 16, 17 ). Conversely, females are only tentatively identified if strictly associated with males from the same locality. Based on the plentiful material examined here, it is concluded that D. vockerothi occurs infrequently in the Mascarenes, or at least on the beaches where the fly material was sampled, despite the wide distribution of this species on the seashores of the Oriental and Australasian/Oceanian Regions. These records, from the western Indian Ocean, represent the western-most occurrence of this prevalently Pacific Ocean species. Dasyrhicnoessa vockerothi is recorded here for the first time from the Mascarenes.

Figures

FIGURES 10–12. Mid femora and tibiae of male beach flies (posterior views). 10. Dasyrhicnoessa insularis (Aldrich). 11. D. ferruginea (Lamb). 12. D. vockerothi Hardy & Delfinado. Scale bar = 0.3 mm.

FIGURES 13–18. Male terminalia of beach flies. 13. Afrotethina aurisetulosa (Lamb), right surstyli in posteromesial view (after Munari 1988). 14. Pseudorhicnoessa rattii Munari, left lateral view (after Munari 1981). 15. Same, P. spinipes Malloch (after Sasakawa 1974). 16. Same, Dasyrhicnoessa insularis (Aldrich) (after Foster & Mathis 1998). 17. Same, D. vockerothi Hardy & Delfinado (after Sasakawa 1995). 18. Same, D. ferruginea (Lamb). Scale bars: 13 = 0.05 mm; 14–15 = 0.3 mm; 16–18 = 0.1 mm. Abbreviations: a sur—anterior surstylus; p sur—posterior surstylus.

FIGURES 25–29. Distribution maps of beach flies on Mauritius sampled in 2018. 25. Afrotethina aurisetulosa (Lamb). 26. Dasyrhicnoessa ferruginea (Lamb). 27. D. insularis (Aldrich). 28. D. vockerothi Hardy & Delfinado. 29. Pseudorhicnoessa rattii Munari.

FIGURES 30–34. Distribution maps of beach flies on Rodrigues sampled in 2018. 30. Afrotethina aurisetulosa (Lamb). 31. Dasyrhicnoessa ferruginea (Lamb). 32. D. insularis (Aldrich). 33. D. vockerothi Hardy & Delfinado. 34. Pseudorhicnoessa rattii Munari.