Cylindrotoma japonica, ALEXANDER, 1919

Imada, Yume, 2021, Moss mimesis par excellence: integrating previous and new data on the life history and larval ecomorphology of long-bodied craneflies (Diptera: Cylindrotomidae: Cylindrotominae), Zoological Journal of the Linnean Society 193, pp. 1156-1204 : 1177

CYLINDROTOMA JAPONICA ALEXANDER, 1919

( FIGS 1E , 4B , 5A , 6A , 7A–C , 10A , 11A, B , 12A–K , 13A–D )

Figures

Figure 1. Life history of Cylindrotominae. (A) First-instar larva of Triogma kuwanai consuming fluid within a leaf of Plagiomnium vesicatum (Mniaceae), dorsal view; cells devoid of chlorophyll (black arrowheads) indicate the piercing-andsucking feeding method. (B) Final-instar larva of Liogma brevipecten chewing a leaf margin of Rhizomnium tuomikoskii (Mniaceae), lateral view; note that the head capsule is fully retracted within the lip-like cuticular lobe. (C) Pupa of Liogma brevipecten with a green hue and displaying transverse black stripes in abdominal segments, dorsal view. (D) Copulating couple of Liogma mikado on moss tufts; the female, on the left, was dragged out of the pupal exuvium by the male and thus the body has not been completely sclerotised. (E) Leaf of Stellaria (Caryophyllaceae) with two characteristic incisions in the epidermis of the lower leaf surface (white arrowheads) due to endophytic oviposition; the eggs are absent. (F) Egg of L. mikado laid on a shoot of Hylocomnium splendens (Hylocomniaceae). (G) Larva of C. japonica, which is being preyed upon by what is presumably a third-instar nymph of Himacerus apterus (Hemiptera: Nabidae). Scale = 1 mm.

Figure 4. Coloration and patterning of larval Cylindrotominae. (A) Dissected integuments of larvae with a green hue of L. brevipecten (left) and L. mikado (right). Note that there is a marked difference in integument colouration between them and that L. mikado has a yellowish tint. (B) Final-instar larva of Cylindrotoma japonica drowned in a wet spot on a leaf. The transparency of the integument is evident, with a shiny, silvery ventral side. (C–D) Colour dimorphism in Liogma mikado. (C) Late-instar larva of Liogma mikado with a green hue, blending in well in a tuft of Plagiothecium euryphyllum (Plagiotheciaceae). (D) Late-instar individual with a brown hue, occurring on the same moss patch as (C).

Figure 5. Schematic diagram illustrating diverse arrangements and numbers of the elongated cuticular lobes in 11 cylindrotomine species. Each diagram represents a simplified larval body, longitudinally grouped into six, based on the patterned arrangements of the lobes: (1) prothorax, (2) meso- and metathorax, (3) abdominal segment I, (4) abdominal segment II, (5) abdominal segments III–VII, and (6) abdominal segment VIII (anal segment). Each square partitioned by double lines in a row denotes the integument on the dorsal (dl), lateral (la), ventral (vl) sides of the corresponding segment(s). Each black dot symbolizes a cuticular lobe, of which position/size in a given space express the relative position/size of the lobe.Anal papillae are not shown. Lobe forms, auxiliary outgrowths, and relative length of segments are not shown here (see each species' own description). Each taxon name is abbreviated. For G and I, diagrams are based on the description in Brodo (1967) and Peus (1952), respectively; caution is needed when these are compared with the species examined herein (A–F, I–K), because the lobe characteristics could be treated differently in the previous studies. For K, a single lobe is present at the location of asterisk (*) only in the abdominal segment VII but not in the other segments.

Figure 6. Comparative morphology of dorsal elongated cuticular appendages on abdominal segment in cylindrotomine larvae at late instar. (A) Cylindrotoma japonica. (B) Diogma glabrata. (C) Liogma brevipecten. (D) L. mikado. (E) L. nodicornis. (F) L. serraticornis. (G) Triogma kuwanai. (H) Phalacrocera replicata. For C, E and H, body colour is faded away due to preservation in alcohol. Scale = 1 mm.

Figure 7. Ultrastructure of dorsal integument, SEM views. Dorsal integument with elongated cuticular lobes of abdominal segment at larval stage. Cylindrotoma japonica (A–C). (A) General dorsal integument. (B) Dorsal elongated lobe. (C) Ditto, closer view. Liogma brevipecten (D–F). (D) General dorsal integument. (E) Dorsal elongated lobe, lateral side. (F) Ditto, frontal side. Phalacrocera tipulina (G–I). (G) General dorsal integument to which diatoms and debris are sparsely attached. (H) Ditto, closer view. (I) Dorsal elongated lobe. Scales are shown in each image.

Figure 10. Spiracular lobes of cylindrotomine larvae. (A) Cylindrotoma japonica, dorsal view. (B) Liogma nodicornis, caudal view. (C) L. brevipecten, oblique dorso-caudal view. (D) Phalacrocera replicata, caudal view. (E) P. tipulina, caudal view. Abbreviations: anp, anal papilla; dac, accessory dorsal lobe; dl, dorsal lobe; dm, dorsomedial lobe; ha, hair fringe; sp, spiracle; spd, spiracular disc; vl, ventral lobe. Scale = 2 mm.

Figure 11. Ultrastructure of spiracular field of cylindrotomine larvae, SEM views. (A–B) Cylindrotoma japonica. (A) Spiracular field is devoid of hair fringe. (B) Ditto, closer view. (C–D) Liogma brevipecten. (C) Spiracular field is present on the lobe fringed with hairs. (D) Ditto, closer view. (E–F) Phalacrocera tipulina. (E) Spiracular field on the lobe with hair fringe. (F) Ditto, closer view. White arrowheads denote apertures in the central plugs. Scales are shown in each image.

Figure 12. Biology and morphology of Cylindrotoma japonica. (A) Anterior body of the final instar; body colour faded due to ethanol preservation: anteriormost part of prothorax to abdominal segment III, dorsal view. (B) Abdominal segments III–V showing pairs of lobes, ventral view. (C) Thick prothoracic integument in which the larval head is covered, which constitutes a ‘suction cup’. (D) Crown-shaped material covering the larval prothoracic integument, which is presumably composed of silk and debris. (E) Anal segment, ventral view. (F) Second-instar larva carrying its own faecal pellets on the dorsal and lateral sides of the integument. (G) Early-instar larva with green hue and grey pigmentation on the dorsal segments. (H) Lateinstar larva with brown hue. (I–K) Snapshots showing a sequence of the looping locomotion of a late-instar larva when ascending a plant stem. (I) The larva arches its body forward using both its mouth (as a sucker) and anal segment attached to the substrate. (J) The larva releases the mouth while the anal segment is wrapped around the substrate to get a grip. (K) The larva then wobbles from side to side to crawl forward. Abbreviations: dl, dorsal lobe; la, lateral lobe; vl, ventral lobe. Scale = 1 mm.

Figure 13. Ultrastructure of Cylindrotoma japonica final-instar larva, SEM views. (A) larval head loaded with a mass of secretion (presumably silk material); secretion is reticulated and entirely conceals the head capsule but a small, circular opening is present near the centre (white arrowhead), which leads to the mouth underneath. (B) Close-up view of a secretion mass, which provides a cap for the head capsule, revealing delicate reticulated threads. Bright flaring is due to sample charge. (C) Isolated threads of the ventral thoracic segment; note that the diameter is greater than that of head part threads in image B. (D) Ventral lobe on abdominal segment VII, in which the cuticular surface is worn out due to abrasion. Scales as shown in each image.