Colonies effuse, hairy. Conidiophores mononematous, macronematous, unbranched, septate, brown, becoming paler towards the apex, arising from enlarged radial base. Conidiophore up to 50–120 µm long and 6 µm wide at the base, tapering to 3.5 µm near the apex and then constricting rapidly before enlarging into a denticulate apex. Conidiogenesis terminal, determinate, sympodial. Denticles hyaline, up to 3 × 1 µm. Conidia hyaline, fusiform with rounded apex, slightly asymmetric, 20–30 × 3.5–4 µm

Coloniae effusae, hirsutae. Conidiophora mononematosa, macronematosa, non ramosa, septata, brunnea, ad apicem pallescentia, ex basi radiale augita, usque 50–120 µm longa et basi 6 µm lata, subapice 3.5 µm attenuata, infra apicem praecipite constricta sed in apice dilatata et denticulata. Evolutio conidiorum terminalis, determinata, sympodialis. Denticulae hyalinae, usque 3 × 1 µm. Conidia hyalina, fusiformia, apice subrotundata, leniter asymmetrica, 20–30 × 3.5–4 µm

This species clearly fits within Dactylaria section Diplorhinotrichum as defined by de Hoog (1985). Goh & Hyde (1997) provided a key to species of Dactylaria. Dactylaria leptospermi differs from D. nervicola Upadhyay & Mankau and D. arecae (Matsush.) R.F.Castañeda & W.B.Kendr., both of which have acropleurogenous conidiogenesis and conidia sometimes pale brown; it differs from the latter in having shorter conidia (12–24 µm). Two other species show some similarity to D. leptospermi. Dactylaria cazorlii Mercado, Gené & Guarro has similarly shaped conidia but these have 4–6 septa and a conidiophore that is constricted atthe base. The closest species is D. plovercovensis Goh & K.D.Hyde, which has similar conidiophores but much smaller denticles (0.5–1.5 µm) and with shorter and wider conidia 16–22 × 4–4.5 µm.

HOLOTYPE: Auckland, Karekare, dead stem of Leptospermum scoparium, 18 Mar 2001, PDD 76620 [74982=error in paper], ICMP 1429 [14247=error in paper] (ex Type).