NAUCORINAE LEACH, 1815

Sites, Robert W., 2022, Phylogeny and revised classification of the saucer bugs (Hemiptera: Nepomorpha: Naucoridae), Zoological Journal of the Linnean Society 195, pp. 1245-1286 : 1268-1269

SUBFAMILY NAUCORINAE LEACH, 1815

FIGS 10H , 11H , 17 , 19 , 22–25

Type species: Naucoris maculatus Fabricius, 1798 .

Taxonomic history: The nominate subfamily was recognized as the division Naucoraria by Stål (1876) to include Ilyocoris , Macrocoris , Naucoris and Pelocoris . The group was referenced as subfamily Naucorinae by Montandon (1900) when describing Macrocoris parviceps . Since then, additional genera have been described and placed in Naucorinae , but the subfamily was not based on any synapomorphies and the monotypy has been considered doubtful (e.g. Sites & Mbogho, 2012). The genus Carvalhoiella was described in Ambrysinae ( De Carlo, 1963) , then was transferred to Naucorini ( Nieser, 1975) , but was later transferred back to Ambrysinae ( Nieser et al., 1999) . Zettel (2001) suggested the tribe Ilyocorini to contain Ilyocoris , Pelocoris and Placomerus and Naucorini to contain Asthenocoris , Macrocoris , Nanonaucoris , Naucoris , Neomacrocoris , Philippinocoris , Stalocoris and Thurselinus Distant, 1904 . In the description of Halmaheria, Zettel (2007) noted a series of attributes suggesting a close relationship of this new genus with both Sagocorini ( Cheirochelinae ) and Naucorini (Naucorinae) . Therefore, he transferred the Philippine genera of Sagocorini ( Asthenocoris , Philippinocoris and Stalocoris ) to Naucorini . Recently, Pelocoris was transferred from Naucorinae to Ambrysinae (ReynosoVelasco & Sites, 2021) .

Revised taxonomy: In my Most Probable Phylogeny dendrogram ( Fig. 9 ), I substituted the ML topology of Clade O, the predominantly New Guinean clade, into the BI dendrogram to represent what I consider to be the most plausible, supported evolutionary relationships within the subfamily. The revised subfamily Naucorinae presented in the Most Probable Phylogeny has four major clades ( Fig. 18 ), each of which represents a tribe and includes a species of Naucoris ( Fig. 19 ) at its root with strong support. Because the genus Naucoris , as currently conceived, is clearly polyphyletic, new genera will be necessary for species of Naucoris in all but one clade. Because these species were previously considered congeners, morphological distinctions supporting their recognition as multiple genera are not evident in some cases. Nonetheless, the molecular evidence presented here that Naucoris as currently conceived is polyphyletic is strong.

Diagnosis: With the recent transfer of Pelocoris to Ambrysinae , Ilyocoris and Placomerus to Ilyocorinae , and Macrocoris and Neomacrocoris to Macrocorinae , a clear synapomorphy among genera in Naucorinae is now evident. The male parameres are large, crisscrossing and dramatically asymmetrical in all species. More specifically, the left paramere overlaps the right and is broader and slightly shorter than the right. The right paramere tends to have a sulcus or elongated fossa on its right side to accommodate the left side of the aedeagus shaft. Both parameres wrap around and embrace the aedeagus ( Fig. 11h ).

Comments: Because each of these tribe groups has one or more species of Naucoris at the root, this suggests that an especially vagile ancestral Naucoris -like taxon dispersed widely, giving rise to multiple independent lineages of naucorids. This concept was astutely hypothesized by Polhemus & Polhemus (1987) when considering the origins of the Philippine and New Guinean stock based on head structure and male genitalia. We now have strong corroborating molecular evidence for these relationships.

Figures

Figure 9. Most Probable Phylogeny dendogram based on Bayesian inference with substitutions from maximum likelihood for Laccocorinae (except Ctenipocorini trib. nov. and Idiocarini trib. nov.). Closer views of Laccocorinae and Naucorinae individually can be seen in Figures 13 and 18, respectively.

Figure 10. Habitus examples of each subfamily: Ambrysinae: Ambrysus signoreti (a), Cheirochelinae: Cheirochela thailandana (b), Cryphocricinae: Cryphocricos hungerfordi (c), Ilyocorinae: Ilyocoris cimicoides (d), Laccocorinae: Laccocoris limicola (e), Limnocorinae: Limnocoris inornatus (f), Macrocorinae subfam. nov.: Macrocoris flavicollis (g), Naucorinae: Naucoris scutellaris (Thailand) (h).

Figure 11. Examples of male genital capsule with pygophore, aedeagus and parameres (terga IX and X removed) for each subfamily: Ambrysinae: Ambrysus lunatus (a), Cheirochelinae: Coptocatus kinabalu (b), Cryphocricinae: Cryphocricos hungerfordi (c), Ilyocorinae:Ilyocoris cimicoides (d), Laccocorinae: Laccocoris spurcus (e), Limnocorinae: Limnocoris ovatulus (f), Macrocorinae subfam. nov.: Macrocoris flavicollis (g), Naucorinae: Afronaucoris gen. nov.: Afronaucoris madagascariensis (h).

Figure 17. Lateral view of head and prothorax of Philippinocoris usingeri showing anteromedian tooth of prosternum (white arrow).

Figure 18. Detail of Most Probable Phylogeny dendogram of Naucorinae, based primarily on Bayesian inference, but with maximum likelihood topology substituted for Idiocarini trib. nov. All species of Afronaucoris gen. nov. and Australonaucoris gen. nov. are new combinations. The red box in the inset shows the part of Figure 9 depicted in this figure.

Figure 19. Revised generic representation of the former genus Naucoris. Dorsal habitus of Naucoris maculatus (a), Australonaucoris congrex (b), Afronaucoris parvulus (c), Indonaucoris minutus sp. nov. (d).

Figure 22. Afronaucoris obscuratus male: dorsal habitus (a), genital capsule with terga IX and X removed (b), left and right parameres (c), distal part of aedeagus (d). Sizes are not proportional among figures.

Figure 23. Australonaucoris congrex male: dorsal habitus (a), genital capsule with parameres and terga IX and X removed (b), left paramere (c), right paramere (d). Sizes are not proportional among figures.

Figure 24. Indonaucoris minutus gen. nov., sp. nov.: dorsal habitus (a), ventral habitus (b), genital capsule (c), genital capsule with terga IX and X removed (d), left and right parameres (e), dorsal and ventral views of mesothoracic leg (f), dorsal and ventral views of metathoracic leg (g). Sizes are not proportional among figures.

Figure 25. Tamhini stream, the presumed type locality of Indonaucoris minutus gen. nov., sp. nov., in December 2019. Photo courtesy of Shruti Paripatyadar.