The Weta 40: 39-41 (2010) 39 trochanteratum Edwards (Diptera: ) - a marine invader from Chile.

John Leader, 66 Lakings Rd., Blenheim ([email protected])

Introduction and Results The increase in maritime trade in the recent past has enabled the rapid opportunistic intercontinental movement of many marine organisms. Larvae of the marine species of the dipteran genus Telmatogeton (Chironomidae) are well adapted to take advantage of such traffic. Wirth (1947) notes that although the adults live for only a few hours, the larvae, which live preferentially in sites of high current flow in the tidal splash zone, take some time to complete their development. Brodin and Anderson (2008) point out that the larvae of T. japonicus have the ability to withstand harsh and highly variable conditions and their habit of living in a tube bound to a solid substrate enables them to attach themselves to the hulls of ships. In fact, Kerckhof (in ICES 2005) records their occurrence on ships‟ hulls. The rapid spread of T. japonicus through the European seaboard by this method has been fairly well documented. The first record was just north of the major shipping port of Kiel in Germany (Rommert 1963). By the mid 1990s it had been recorded from the shores of Poland, Germany and Sweden and by 2008 it had invaded eight further countries (Portugal, Ireland, Belgium, the Netherlands, England, Denmark, Norway and Iceland) (Brodin and Anderson 2008). In 2009 it was also recorded from Finland (Raunio, Paasivirta and Brodin, 2009).

In 1998, on a visit to Hokitika, many large were observed running rapidly over an algal-covered rock in the intertidal near low water mark. A number was collected, together with larval cases from the substrate. Later examination revealed the adults to be Telmatogeton trochanteratum. This species was first described by Edwards (1931) from material collected at Ancud , Chile, on rocks covered with Enteromorpha, and exposed only at low tide. Apart from its large size, the male of this species is instantly recognisable by characteristic features of the antennae, in which the terminal segment is more than twice as long as wide, pale at the base and abruptly narrowing to a dark, nipple-like tip, (Fig 1a), and by the finger-like protrusion, more than twice as long as wide, on the inner face of the mid-trochanters (Fig 1b). Other specific features of the adult male are listed by Edwards (1931), and summarised by Wirth (1947). On at least two subsequent occasions an extensive search of the area failed to find any further trace of the , and the capture was dismissed as an accidental and transient occurrence until March 2009, when several adults were captured at Ward Beach in Marlborough. This suggests that the is now established and widely distributed in the South Island of New Zealand.

40 John Leader

Figure 1. Telmatogeton trochanteratum. a. antenna; b. trochanter of mid leg.

Edwards (1931) gave a detailed description of the male adult but included no measurements. Wirth (1947) gives a Table recording leg ratios (length of basitarsus divided by length of tibia) for 9 of the 13 species then known, and antennal ratios (length of the distal segment divided by the length of the remaining flagellar segments) for 7 species, but not for T. trochanteratum. In this species the antennal ratio is 0.48 (.44-.54, n=5), and the leg ratios are: foreleg , 0.58, mid-leg, 0.38, hind leg, 0.51. The relative lengths (anterior tibia = 1) of the leg segments, femora, tibia and tarsal segments is as follows: Anterior; 1,1, 0.57, 0.13, 0.12, 0.15; Middle; 1.34. 1.14. 0.43, 0.15, 0.08, 0.14; Posterior; 1.45, 1.25, 0.63, 0.30, 0.10, 0.14. Neither Edwards nor Wirth comment on the adult female, which is smaller than the male. The paired terminal claws on each leg are simple and pointed. Unlike the female of T. sancti-pauli, the mid-trochanters lack a protuberance. Female antennae similar to male. Larvae. According to Cranston (1983) larval can be readily separated from other chironomid Subfamilies, but no means exists of separating the species. The larvae of T. trochanteratum live in silken cases on rock between attachments of the green alga, Enteromorpha, near the low tide mark. The case is sealed prior to pupation.

Discussion Brodin and Andersen(2008) discuss at length the potential adverse consequences of the spread of T. japonicus in the Baltic. They conclude that while there is at present no evidence that the species is harmful, its rapid spread and ability to colonise eutrophic and brackish conditions may lead to harmful effects in areas where native species are protected. On New Zealand shores there are several endemic species of Telmatogeton which occupy broadly similar habitats. It will be interesting to observe the future spread of T, trochanteratum and its effect on these endemic species.

A marine invader from Chile 41

References Brodin Y, Anderson MH. 2008 The marine splash (Diptera; Chironomidae) – extreme and alien? Biological Invasions 11: 1311- 1317.

Cranston PS. The larvae of Telmatogetoninae (Diptera: Chironomidae) of the Holarctic region – Keys and diagnoses. Entomologica Scandinavica Supplement 19: 17-22.

Edwards FW. 1931 “Chironomidae.” Diptera of Patagonia and South Chile. Part 2, fasicle 3: 303-307. British Museum Publications.

Kerckhof F. 2005 In: ICES (International Council for the Exploration of the Sea) Report of the working group on introduction and transfers of marine organisms. ICES CM 2005/ACME:05; 1-173.

Rauni J, Paasivirta L, Brodin Y. 2009 Marine midge Telmatogeton japonicus Tokunaga (Diptera: Chironomidae) exploiting brackish water in Finland. Aquatic Invasions 4: 405-408.

Remmert H. 1963 Telmatogeton remanei n.sp. eine neuemarine Chironomide aus der Kiele Förde. Zoologische Anzeige 171: 165-178.

Wirth WW. 1947. A review of the Genus Telmatogeton Schiner, with descriptions of three new Hawaian species (Diptera: Tendipedidae). Proceedings of the Hawaian Entomological Society XIII: 143-191.