Mortoniella (Mortoniella) spinulata ( Flint, 1991 )

Blahnik, Roger J. & Holzenthal, Ralph W., 2017, Revision of the northern South American species of Mortoniella Ulmer 1906 (Trichoptera: Glossosomatidae: Protoptilinae) *, Insecta Mundi 2017 (602), pp. 1-251 : 86-87

Mortoniella (Mortoniella) spinulata ( Flint, 1991)

Fig. 72

Mexitrichia spinulata Flint 1991: 22 .

Mortoniella spinulata (Flint) : Blahnik and Holzenthal 2008 [member of leroda species group]; Blahnik and Holzenthal 2011 [incertae sedis to species group].

Mortoniella spinulata is probably most similar to M. cornuta , n. sp. Both species have very narrowly divided apical lobes on tergum X, and a correspondingly narrowed apex of the dorsal phallic spine. Mortoniella spinulata can be distinguished from M. cornuta , and other species of the argentinica subgroup, by the presence of spinose dorsal lobes on the inferior appendages. Mortoniella spinulata also lacks the horn-like lateral projections on the dorsal phallic spine that characterizes M. cornuta . The two pairs of paramere appendages in M. spinulata differ in shape and most closely resemble those of M. croca , n. sp. in that the shorter one is very narrow and hooked apically. Mortoniella croca can be easily distinguished in having a very wide V-shaped mesal invagination of tergum X, and by having a much reduced, nearly vestigial, dorsal lobe on the inferior appendages.

Adult —Length of forewing: male 4.1 mm. Forewing with forks I, II, and III present, hind wing with forks II, III, and V. Spur formula 0:4:4. Head distinctly small. Overall color dark brown. Tibial spurs slightly darker than legs, contrasting in color. Wing bar at anastamosis indistinctly marked with white setae.

Male genitalia —Ventral process of segment VI laterally compressed, large, subtriangular, ventrally directed, length subequal to width at base, apex acute, process not retracted anterobasally. Segment IX nearly evenly rounded anterolaterally, length greatest midlaterally, posterolateral margin slightly produced, narrowing ventrally; segment deeply mesally excised dorsally and ventrally, forming lateral lobes, separated dorsomesally by much less than ½ width of segment. Tergum X short with very elongate setae, basally with rounded elevation, ventrolateral lobes prominent, projecting laterally; overall shape of tergum, in dorsal view, subquadrate, with mesal pair of very narrowly separated, spine-like, apicolateral lobes; apices of ventrolateral lobes angular, prominent. Inferior appendages with elongate, narrow, posteriorly recurved, dorsolateral lobes, with row of spines in apical ½, apex of dorsolateral lobe very narrowly attenuate; apicoventral projections absent. Mesal pockets of inferior appendage with spine-like apical processes elongate, posteriorly projecting. Paramere appendages doubled, one pair elongate, narrow (extending about as far as dorsal phallic spine), slightly widened in apical ½ and strongly mesally curved, widened apex covered with minute spines; second, lateral pair about ½ length of first pair, very narrow throughout, distinctly hooked apically, apex acute. Dorsal phallic spine distinctly widened in middle in both lateral and dorsal views, apical 1/3 dorsally inflected and very narrow, apex acute, ventral margin of spine at apical inflection with distinct small tubercle or protuberance, articulating with sclerotized depression in dorsal margin of endophallic membrane. Phallobase with small, lightly sclerotized, mesal apodeme. Phallicata tubular, with pair of short rounded ventrolateral projections and additional pair of rounded ventromesal projections near apex. Endophallic membrane elongate, with depressed dorsal sclerite, accommodating reflexed apex of dorsal phallic spine; phallotremal spines small, distinct, apical.

Material examined — COLOMBIA: Antioquia: Quebrada Espadera, 7 km N Medellín, 24.ii.1983, OS Flint, Jr– 2 male Paratypes (pinned) (NMNH).

— esrossi subgroup

Included species: Mortoniella esrossi , n. sp.

The single species listed here is placed in its own subgroup because it is morphologically distinct from other species. It is characterized by having paramere appendages that lack typical rounded basal processes; instead, the appendages lie parallel to the dorsal phallic spine and are each accompanied by a projecting ventral lobe (which could be a modification of the usual basal process). Mortoniella esrossi is also unusual in that the dorsal phallic spine seems to have a ventral “foot” in its apical part. This may reflect a fusion of the dorsal phallic spine with dorsal margin of the endophallic membrane. A similar development seems to occur in M. curvistylus , n. sp. in the argentinica subgroup, but whether an actual fusion occurs in either species is not easily determinable. An additional unusual feature of M. esrossi is a large endophallic spine with two branches, which may be a modification of the small phallotremal spines found in some other taxa. Like a number of the “unplaced species” discussed here, the inferior appendages have narrow, reflexed dorsal lobes, and spine-like projections from the mesal pockets of the inferior appendages that are relatively elongate. The presence of these features in what are otherwise very divergent taxa suggests that they may be plesiomorphic for the subgenus Mortoniella in general, in which case they would have had to been lost in various lineages, including the majority of taxa in both the leroda and bilineata groups. Other aspects of the morphology of M. esrossi suggest a possible relationship to the tridens subgroup, but these are admittedly subject to interpretation. Among these are the paramere appendages, which seem to be in a transitional stage of fusing to the dorsal phallic spine; also, the projecting ventral lobe at the base of each of the appendages is similar to that from which a second pair of appendages emerges in the tridens subgroup. If the latter represents a homology, a second pair of appendages may also have been present in the ancestor of M. esrossi , but secondarily lost. An additional character suggesting a relationship is the more or less subquadrate tergum X found in both M. esrossi and members of the tridens subgroup.

Figures

Figure 72. Mortoniella (Mortoniella) spinulata (Flint), male genitalia. A—lateral; B—segment IX and tergum X, dorsal; C—phallic ensemble, ventral; D—dorsal phallic spine, dorsal.