Supplemental figure legends Figure S1. Multiple sequence alignments of Photuris gene products used in this study. All sequences aligned in MEGA5  using MUSCLE . Figures generated in BioEdit . Identical amino acid positions shaded in black and similar (BLOSUM62) positions shaded in gray. (A) Photuris Abdominal-B fragment aligned with full-length orthologs from other insects: T.c., Tribolium castaneum (NP_001034519.1); P.h.c., Pediculus humanus corporis (XP_002425762.1); B.m., Bombyx mori (BAH30152.1); D.m., Drosophila melanogaster (AAF55362.1). Homeodomain region spans positions 407-465. GenBank accession number: KC190488. (B) Photuris abdominal-A fragment aligned with full-length orthologs from other insects: T.c., Tribolium castaneum (EEZ99248.1); B.m., Bombyx mori (ACD10794.1); A.m., Apis mellifera (XP_394120.4); A.p., Acyrthosiphon pisum (XP_001944629.2). Homeodomain region spans positions 303-362. GenBank accession number: KC190489. (C) Photuris Distal-less fragment aligned with full-length orthologs from other insects: T.c., Tribolium castaneum (NP_001034528.2); B.a., Bicyclus anynana (AAL69325.1); A.m., Apis mellifera (NP_001124509.1); D.m., Drosophila melanogaster (NP_523857.1). Homeodomain region spans positions 164-224. (C’) Photuris Distal-less fragment nucleotide sequence (excluding variable degenerate primer regions). We include this as the cloned fragment length was less than that required for database submission. (D) Photuris dachshund fragment aligned with orthologs from other insects (orthologous sequences trimmed from 5’ and 3’ ends for space): T.c., Tribolium castaneum (XP_969771.2); P.h.c., Pediculus humanus corporis (EEB15130.1); O.f., Oncopeltus fasciatus (AAS93632.1); C.q., Culex quinquefasciatus (EDS43047.1). Truncated Ski domain spans positions 1-50. GenBank accession number: KC190490. Figure S2. Abd-B RNAi results in disruption of PO formation A) Sagittal section through adult wildtype Photuris lantern. Note differentiation into dorsal- and photic layers, abundance of tracheae, columnar organization of the photic layer separated by tracheal conduits, and translucent cuticle. B) Section of corresponding tissue region obtained from adult Abd-BRNAi individual. Note absence of tracheae, lack of tissue differentiation into dual cell-layers, loss of columnar organization, and ectopically pigmented cuticle. Ventral is down and magnification is 20X in both images.