Female N. asekiense comb. nov. is most often confused with the sympatric species N. frondosum comb. nov., but N. asekiense comb. nov. can be differentiated by the presence of small exterior pro- and meso-tibial spurs, which N. frondosum comb. nov. lacks.

Only two male N. asekiense comb. nov. are known at present, but their morphology is consistent between them for all features except for the abdominal shape (see Fig. 17E, F for side by side comparison of these two males). An additional specimen of Nanophyllium rentzi also shows how variable male abdominal morphology can be within the same species while the other morphological features remain stable (Fig. 18A, B). Nanophyllium asekiense comb. nov. males can be differentiated from the other known Nanophyllium males based on the profemoral lobe morphology. In N. asekiense comb. nov. the interior profemoral lobe is distinctly right-angled (a feature present in all species of the pygmaeum species group (Fig. 11E–H) except N. australianum which has a thinner, obtuse angle; Fig. 11D), but the exterior profemoral lobe of N. asekiense comb. nov. is narrow, only about the same width as the profemoral shaft; Fig. 11E (more like N. australianum than any other species, as the other species instead have an exterior profemoral lobe which is broader than the width of the profemoral shaft; Fig. 11F–H).

Male. Coloration. Each antennal segment with dark brown and tan coloration. The rest of the body and legs are of a yellow-green based color, with variable brown margins. In the two males bred by the Montreal Insectarium the individual with the undulating abdomen has minimal brown markings, with only brown along the leg margins and the abdomen margins (Fig. 17E). The male with the straight abdominal margins has more prominent brown markings throughout, with around half of the leg lobes marked with brown and a wider brown abdominal margin (Fig. 17F). The alae and tegmina on both males are a translucent pale green, with small flecks of dark brown along the prominent veins.

Morphology.Head. Head capsule about as long as wide, with a vertex that is lumpy without notable granulation, two posteromedial tubercles are not notably large but are present with a slight furrow between them (Fig. 19D). Compound eyes are notably protruding from the head capsule and there are three well-developed ocelli between and slightly posterior to them (Fig. 19D). Antennae. The antennae are longer than the outstretched forelegs and consist of 23 antennomeres (Fig. 19D). The scapus and pedicellus are nearly bare, with only a few short clear setae. All segments beyond the scapus and pedicellus except for the terminal four are covered in stiff dark setae which are each longer than the segment they are on is wide. The terminal four antennal segments also have dark setae, but these setae are shorter than the segments are wide (Fig. 19D). Thorax. Pronotum as wide as it is long with moderately formed rims on the lateral margins that are mostly parallel and only gently converging near the posterior, the anterior margin is slightly curved with a prominent rim, and the posterior margin is weakly formed (Fig. 19B). Surface of the pronotum has a distinct sagittal furrow and central lateral furrow, and the surface is irregularly lumpy, but not granular (Fig. 19B). Prescutum significantly wider than long, at its widest on the anterior it is 2.5 times wider than long. The prescutum margins evenly converge toward the posterior and have two or three notable nodes on the anterior portion, and the remainder of the margin is irregularly lumpy. Surface of prescutum is nearly smooth without significant features, and the anterior prescutum margin is simple, also lacking nodes or spines (Fig. 19B). Mesopleurae gradually diverging wider from anterior to the posterior, and marked with irregularly shaped tubercles throughout, with around four notably larger ones and smaller nodes intermixed (Fig. 19B). Mesopleurae surface irregularly lumpy with a single distinct pit in the center and no notable nodes. Pro-, meso-, and meta-sternum with irregularly spaced granules mostly along the sagittal plane but with the margins occasionally with sparse granules. Wings. Tegmina short, not exceeding the posterior of the metathorax. The subcostal vein and any splitting of the radius is obscured within an area of the wing that is highly sclerotized. The radius is the most prominent vein and runs through the center of the tegmina to the posterior margin (along the edge of the highly sclerotized patch). The medial vein is also prominent and runs through the center of the tegmina parallel with the radius and does not appear as though the media has any notable splits. The cubitus and first anal are moderately formed and give stability to the other half of the tegmina, are not notably branched, and this half of the tegmina is not as heavily sclerotized as the other half. The first anal fuses with the cubitus around two thirds of the length, and the cubitus runs nearly to the wing margin. Alae developed, with the exposed section of folded alae slightly sclerotized, but not as sclerotized as the alae. The costa runs along the wing margin with a weak subcosta running along and eventually fusing with it. The radius splits into the first radial and the radial sector just distal to the wing midline and these two veins run separately to the wing margin without fusing to others. The media splits into the media anterior and the media posterior almost immediately near the base of the wing. The media posterior fuses back to the media anterior near the distal one fifth of the wing, and then the fused medial veins run to the wing margin (Fig. 13A). The cubitus runs with the first anterior anal for most of the length and then near the distal one fifth of the wing they split and the cubius runs unbranched and unfused to the wing margin. There are seven anterior anals which run simply to the wing margin and four or five well-formed posterior anals which run simply to the wing margin. Abdomen. Abdominal segment II with parallel sides, segment III widening in a smooth arc, segment IV widening slightly for the first half, then gently curving in for the second half, segments V through VIII variable with margins that are either straight and converging uniformly to the apex which gives the abdomen a straight spade-shaped appearance or with margins which each expand and then contract which gives the abdomen a lobed appearance. Abdominal segment IX with margins which slightly converge to the abdominal segment X which is longer than wide and ends in a rounded apex. Genitalia. Poculum broad and ending in a slightly cleft apex that reaches the anterior margin of segment X (Fig. 19C). Cerci densely covered in nodes throughout the surface and short setae mostly on the distal half (Fig. 19C). Vomer long, and slightly bending to the side, not perfectly straight; with sides gradually converging to the upward hooked apex (Fig. 19C). Legs. Profemoral interior lobe angular (approximately 90 degrees) with three small evenly spaced teeth with a nearly straight gap between each tooth (Fig. 19A). Exterior profemoral lobe significantly thinner than the interior lobe (about as wide as the profemoral shaft), only present as a smoothly curved lobe just distal to the midline, not spanning the entire length (Fig. 19A). Protibiae with lobes only present on the proximal half, the distal half is bare. The protibial exterior lobe is a scalene triangle only as wide as the protibial shaft. The interior lobe is also a scalene triangle and about two times as wide as the exterior lobe (Fig. 19A). Mesofemoral exterior lobe smoothly arcing the full length, with the widest portion on the distal half and only about one and a half times as wide as the mesofemoral shaft, with fine serration on the widest portion only. Mesofemoral interior lobe with the majority of the lobe on the distal half, the proximal half with only a sliver of the lobe and lacks teeth versus the wide proximal expanse (about three times as wide as the mesofemoral shaft) has four to five notable serrate teeth. Interior metafemoral lobe with the majority of the lobe on the distal half, with only a thin sliver on the proximal half. The distal half of the metafemoral lobe is two and a half times as wide as the shaft and has five to six serrated teeth. Exterior metafemoral lobe slightly thinner than the metafemoral shaft, spanning the full length, and lacking serration. Mesotibial exterior has a small roundly triangular lobe near the midline which is only about as wide as the mesotibial shaft. Metatibiae lacking exterior and interior lobes.