Enochrus maculiceps

fig. 1: Enochrus maculiceps (male, dorsal habitus, length about 3 mm)

fig. 2: Enochrus maculiceps (aedeagus)

fig. 3: Enochrus tritus (aedeagus)

fig. 4: Enochrus maculiceps (male, lateral habitus, aedeagus inset), from Tamaki Campus, University of Auckland

Taxonavigation

Ordo: Coleoptera
Familia: Hydrophilidae

Name

• Enochrus maculiceps (Macleay, 1871) Wikispecies link

Introduction

• Enochrus maculiceps is a small water beetle known from 'Australia (all provinces & territories except Tasmania), Vanuatu, New Caledonia, and Western Samoa' (Short, 2010: 308)

Notes

• although the presence of this species in New Zealand remains unpublished, it is one of the most common water beetles in and around Auckland City
• I discovered it in New Zealand in the early 2000s, but I cannot say how long before that it may have been here, but nothing was found in a search of collections (NZAC, AMNZ), including unsorted material
• recognising it as different to E. tritus (Wikispecies link), I sent specimens to C.H.S. Watts, who identified them as E. maculiceps
• at least in Auckland City, E. maculiceps is actually far more common than E. tritus, and both species sometimes occur simultaneously in the same pond
• the two species are similar externally, but E. maculiceps is significantly smaller (3 mm) than E. tritus (4.6 mm), and the aedeagus (figs. 2 & 4) is very different to that of E. tritus (fig. 3)
• only one other nominal species of Enochrus has been reported from N.Z., E. abditus (Sharp, 1884) (Wikispecies link), which has not been identified again since the original description, and which potentially could be a junior synonym of E. maculiceps, but this requires further research
• if E. abditus does turn out to be conspecific with E. maculiceps, then it would be unclear how long the species has been present in N.Z., though with a reasonable amount of attention having been paid to N.Z. water beetles in the past, it seems unlikely that a species this common would have been overlooked (the situation is similar with that of the water beetles Allodessus oliveri (?=A. bistrigatus) (Dytiscidae) and Hydraena ambiflagellata (Hydraenidae), both of which are common in Auckland, but must have become so very recently, or else been overlooked in the past)
• like Allodessus oliveri (?=A. bistrigatus), E. maculiceps also occurs in the pond on the Tamaki Campus, University of Auckland (see fig. 4), though water beetles are not common in this pond, possibly due to the abundance of small fish

References

• Short, A.E.Z. 2010: Hydrophilidae: Review of the subtribe Acidocerina of the Southwest Pacific islands (Coleoptera). Pp. 297-318 in: Jäch, M.A. & Balke, M. (eds.): Water beetles of New Caledonia (part 1). Monographs on Coleoptera, 3. ISSN: 1027-8869

Stephen Thorpe 21:19, 16 January 2011 (CET)