Iron longitibius Nguyen & Bae, 2004

Braasch, Dietrich & Boonsoong, Boonsatien, 2010, A contribution to the Heptageniidae (Insecta, Ephemeroptera) of Thailand and Malaysia, Zootaxa 2610, pp. 1-26 : 20-22

Iron longitibius Nguyen & Bae, 2004 (questionable)

Description. Female La: premature; body length 14.0 mm, cerci 13.0 mm (broken).

Head: Almost bluntly triangular (Fig. 83); conspicuous darker mark in the middle of head, anterior face pale whitish and region around antennae and ocelli yellow coloured. Anterior margin of head with short hairs, in the middle somewhat upstanding, laterally reversed. Labrum (Fig. 84): with hairlike setae dorsally and marginally. Mandible (Figs. 85–86) incisors serrate, outer incisor longer than inner incisor. Maxillae (Fig. 87): apex of galea-lacinia terminating with 3 acute teeth, ventral surface of galea-lacinia with submedian row of setae, basal segment of maxillary palp with sparse long hairlike setae, apical segment with numerous hairlike setae. Hypopharynx (Fig. 88): lingua with anterolateral lobes, superlinguae weakly expanded. Labium (Fig. 89): with V-shape separation between glossae, glossae pointed apically, paraglossae slightly expanded laterally, apical segment of labial palp with rows of pectinate and hairlike setae on outer margin.

Prothorax: Femora without distinctively visible patches, dorsally with roundish spot (Fig. 90), femoral bristles (Fig. 91) with lengths of 0.04–0.08 mm, partly positioned in a chagrination field mixed up with fine setal bristles; claws without denticles (Fig. 92).

Abdomen: Yellow-brown; terga (Fig. 93) without comb of pointed tubercles, but with narrow median groove covered with weak fringe of fine hairs up to 0.02 mm (Fig. 94); hind margins of terga with a row of relative strong, acute spines of 0.08 mm (Fig. 94), irregularly substituted by single or some finer spines. Prospective adult dorsal pattern of faint streaks and spots already visible in segments I–III (Fig. 93); segments IV–IX with blurred median double streak posteriorly; sterna light without any pattern. Gill I large, contiguous, gill lamellae II–VI provided with processus, gill VII with fold; lengths of gills I, III, V and VII are 3.5, 2.0, 2.08 and 1.88 mm, respectively (Figs. 95–98). Anterior caudal filaments dark brown, posterior 2/3 portion yellowish.

Diagnosis: Supposed Iron longitibius is a species with a rounded triangular head (Fig. 83), a foretibia of equal length of forefemur (Fig. 90) and a dot-like femur spot (Fig. 90), with tergal spines alternating irregularly (Fig. 94), and having gills III (Fig. 96) and V (Fig. 97) with subquadrangular shape, and gill VII (Fig. 98) with a fold. The figures of I. longitibius in Nguyen & Bae (2004b: p.104, Figs. 7–12) show a head with anterior margin slightly concave, an abdomen with distinct median dark brown markings on terga I–X medioanteriorly, a foretibia 1.2 x length of forefemur and a lack of femur spots.With exception of gill I, each being almost equal, gills are quite different: gill III is oval elongated, gill VII is elongated curved downward, without fold. Further characteristics, i.e. mouthparts, posterior margin of tergum, femur bristles on dorsal face and tarsal claw are not illustrated in Nguyen & Bae (2004b). So, a right comparison, also in view of different stages, is not possible and therefore, provisionally, we place our specimen in Iron longitibius with a question mark.

PLATE XIII. FIGURES 83–89. Larva of? Iron longitibius Nguyen & Bae, 2004 . 83. Head capsule. 84, Labrum, dorsal view (left) and ventral view (right). 85, Right mandible. 86, Apex of right mandible, dorsal view. 87, Left maxilla, ventral view. 88, Hypopharynx, dorsal view (left) and ventral view (right). 89, Labium, dorsal view (left) and ventral view (right).

In contrast to south-east Asian Iron species, Himalayan Iron papillatus Braasch, 2006 bears gills dorsally equipped with papillae and without dorsal spines. Ironopsis -like Iron kapurkripalanorum Braasch, 1983 is likewise without tergal spines, has legs without femora spots, each femur has a fringe of very long hairs on outer margin, and abdominal terga II–VII each has a patch on the mid-dorsal line behind the fore margins. More in western Himalayas, species of the Iron montanus -group, e.g. Iron martensi Braasch, 1981 , rule out by having median row of single spines (‘one-spine-allies’) or exhibit other types of larval terga ( Braasch 1981; Traver 1939). Also Iron suspicatus Braasch, 2006 from Nepal with its conspicuous pattern on terga and sterna is not comparable with the species described herein.

Discussion. Species of genus Iron Eaton, 1883 are rarely spread in Southeast Asia. In Thailand, so far, there is only Iron martinus (s. below), whereas Epeorus occurs in peninsular Thailand, Malaysia ( Braasch & Soldán 1986b: Epeorus hieroglyphicus : Malaysia) and Borneo (Braasch, in preparation; Ulmer 1939), Iron species are missing. The reason might be a generally better adaptive potential to lower temperature and stronger current in Iron (incl. Ironopsis ).

A lack of Epeorus species (incl. Belovius ) with regard to Iron is, based on Kluge (2004), apparent in the high mountain massives of the Caucasus with roughly a REI of 1:9, in Middle Asia of ca 0:12 and in the Himalayas of ca 4:8. In contrast, the REI in South-East Asia including the Greater Sundas distinctly favours species of genus Epeorus with a ratio of 10:2 ( Braasch 1980, 1981a, 1983, 1990, 2006a, 2006b; Braasch & Soldán 1979, 1984a, 1986b; Kluge 2004; Nguyen & Bae 2004a, b; Sites et al. 2001; Ulmer 1939; Webb & McCafferty 2008).

Material examined: premature female La, North THAILAND, Chiangmai Prov., region of Doi Inthanon, 18º31'N, 98º29'E, alt. ca 2000 m; III.1999, bottom sample, leg. R. Braasch.

Deposition: female La ( ZMKU, 80% alcohol).

PLATE XIV. FIGURES 90–98. Larva of? Iron longitibius Nguyen & Bae, 2004 . 90, Foreleg, right, dorsal view. 91, Foreleg femur, bristles on dorsal face. 92, Foreleg, tarsal claw. 93, Abdominal terga. 94, tergum VII, posterior margin. 95, Gill I. 96, Gill III. 97, Gill V. 98, Gill VII.