Leptomorphus walkeri, : Matile, 1977

Borkent, Christopher J. & Wheeler, Terry A., 2012, Systematics and Phylogeny of Leptomorphus Curtis (Diptera: Mycetophilidae) 3549, Zootaxa 3549, pp. 1-117 : 77-78

Leptomorphus walkeri species group

The monophyly of the Holarctic L. walkeri species group is strongly supported by three uniquely-derived synapomorphies (Br = 4): inter-ommatidial setulae absent or present as very few, very short (easily missed) setulae (15:2), setae on basal posterior margin of wing (distal of alula, along base of cell a) all a single length (38:1), gonocoxite bearing gonostylus basally (58:1), and four homoplasious characters: (7:1), lateral ocellus between 0.5 and 1.5X own diameter from eye margin (17:1), median wing spot present (34:1), and alula with microtrichia (37:0) ( Figs. 150, 151, 154).

Leptomorphus walkeri is the sister species to the rest of this group. The remaining species form a strongly supported clade based on one uniquely-derived synapomorphy (Br = 4): sternite 9 ~equal to width of tergite 9 (46:2), and eight homoplasious character states: head brown (1:0), pedicel brown (4:1), frons brown (10:1), calypter with macrotrichia/setae absent (39:1), lateral margins of sternite 9 reaching or overlapping medial margin of gonocoxite (48:0), tergite 9 with posterolateral lobes (evaginations) absent (49:0), and posterior margin of tergite 9 without lobes (50:0, 51:0).

Leptomorphus quadrimaculatus and L. forcipatus form a sister clade to the remaining species. This monophyletic group is supported by one uniquely-derived synapomorphy (Br = 1): length of gonocoxite 1.3–1.79X medial length of tergite 9 (56:1), and four homoplasious character states: aedeagus initially tapered but then swelling and bulbous at apex (66:1), Anterior margin of fusion of parameral and gonocoxal apodemes forming a sclerotized hook (70:2), apex of longest parameral lobe reaching well beyond apex of aedeagus (when anterior margin of apodemes are at same level (72:2), and paramere with two lobes (73:1). Although previously published descriptions of L. subforcipatus and L. talyshensis are included in this manuscript no material was available for study and character coding. These species were initially included in the analysis, but the large amount of missing character data caused polytomies in the tree, so they were omitted to allow greater resolution of species relationships. However, when included in preliminary analyses these species were consistently placed close to L. quadrimaculatus and L. forcipatus . The illustrations of genitalia in the original descriptions support this, as they share the uniquely-derived synapomorphy that unites this clade. Furthermore, L. subforcipatus may be conspecific with L. quadrimaculatus (see taxonomic discussion under these species).

The final five species in this species group comprise the species previously assigned to the subgenus Diomonus ( Matile 1977) , and make up the second most strongly supported clade in the tree (Br = 7, bootstrap = 92). This lineage is supported by one uniquely-derived synapomorphy: sclerotized apex of aedeagus present as lateral lobes only (medial apex absent/indiscernible, 67:2), and 12 homoplasious character states: pedicel with setae and/or bristles only on dorsal apex (5:1), clypeus circular (6:1), many bristles on face (9:0), no inter-antennal bristles on frons (11:2), scutellum brown (23:0), no comb of bristles on male foretibia (30:0), foreleg first tarsomere length 1–1.5X tibia length (31:1), R 4 present (41:0), R 5 concave relative to anterior wing margin (42:1), bristles covering tergite 8 (45:0), length of gonocoxite <0.8X medial length of tergite 9 (56:3), and length of gonocoxite <0.8X medial length of tergite 9 (68:3). Leptomorphus panorpiformis is the sister species to the remaining four (Nearctic) species, which are united by one uniquely-derived synapomorphy (Br = 2): male mid-femur with an apical process ( Figs. 83–84, 32:1), and two homoplasious character states: space between ocelli more than diameter of laterals (16:0), and alula without microtrichia (37:1).

Leptomorphus bifasciatus is the sister species to the rest of the Nearctic clade. The remaining three species ( L. magnificus , L. subcaeruleus and L. nebulosus ) are united by two uniquely-derived synapomorphies (Br = 2, bootstrap = 53): main gonostylar lobe laterally compressed into almost two-dimensional flange (61:1), and aedeagal lateral lobe present as long, thick, sickle-like taper (68:2). These three species (the L. nebulosus group) also have almost identical male genitalia ( Figs. 108, 111, 117), so relationships between the three species are uncertain. However, L. nebulosus does have two homoplasious character states not present in the other two: scape setae in short row on apicodorsal margin and thick patch covering apicoventral process, remainder bare (3:2), and face without bristles (9:1).