Table 1 Homology hypotheses for muscles and glands and their formal descriptions, following the scheme adopted by [30]. Each morphological unit in the left-most column is inferred to be homologous among all four species but has spatial relations, connections and constituents as indicated under each species
Hypothetical homologues | Category of descriptions | Disseta palumbii | Mesorhabdus gracilis | Heterostylites longicornis | Heterorhabdus subspinifrons |
|---|---|---|---|---|---|
MUSCLES | |||||
Esophageal Sphincters (esoS) | Spatial relationships | surround esophagus opening | surround esophagus opening | surround esophagus opening | surround esophagus opening |
Connections | esophagus | esophagus | esophagus | esophagus | |
Forehead-Esophageal Dilator Muscles (for-eso.dM) | Spatial relationships | anterior to esophagus, dorsal to lab-eso.dM2 | anterior to esophagus, dorsal to lab-eso.dM2 and 4 | anterior to esophagus, dorsal to lab-eso.dM2 | anterior to esophagus, dorsal to lab-eso.dM2 |
Connections | esophagus, forehead | esophagus, forehead | esophagus, forehead | esophagus, forehead | |
Constituents | 4 pair of muscles | several muscle bundles | several muscle bundles | several muscle bundles | |
Labrum-Esophageal Dilator Muscles 1 (lab-eso.dM1) | Spatial relationships | anterior to esophagus, lateral to for-eso.dM | anterior to esophagus, dorsal to lg1, lateral to for-eso.dM | anterior to esophagus, lateral to for-eso.dM | anterior to esophagus, lateral to lg3, lateral to for-eso.dM2 |
Connections | esophagus, anterior | esophagus, anterior | esophagus, anterior | esophagus, anterior | |
Constituents | − | − | − | − | |
Labrum-Esophageal Dilator Muscles 2 (lab-eso.dM2) | Spatial relationships | anterior to esophagus, dorsal to u-l.labM4, ventral to for-eso.dM | anterior to esophagus, dorsal to lab-eso.dM4, dorsal to lg1, ventral to for-eso.dM | anterior to esophagus, dorsal to lab-eso.dM4, ventral to for-eso.dM | anterior to esophagus, dorsal to lab-eso.dM4, medial to lg3, ventral to for-eso.dM |
Connections | esophagus, anterior labrum, u-l.labM1 | esophagus, anterior labrum | esophagus, anterior labrum, u-l.labM1 | esophagus, anterior labrum, u-l.labM1 | |
Labrum-Esophageal Dilator Muscles 3 (lab-eso.dM3) | Spatial relationships | − | antero-ventral to esophagus, lateral to u-l.labM2, between lg1 and lg3, ventral to lab-eso.dM2 | antero-ventral to esophagus, lateral to u-l.labM2, between lg1, lg2 and lg3, ventral to lab-eso.dM2 | antero-ventral to esophagus lateral to u-l.labM2, between lg1 and lg3, ventral to lab-eso.dM2 |
Connections | − | esophagus, lateral labrum | esophagus, lateral labrum | esophagus, lateral labrum | |
Labrum-Esophageal Dilator Muscles 4 (lab-eso.dM4) | Spatial relationships | antero-ventral to esophagus, ventral to lab-eso.dM2, dorsal to u-l.labM2 | antero-ventral to esophagus, ventral to lab-eso.dM2, dorsal to u-l.labM2 | antero-ventral to esophagus, ventral to lab-eso.dM2, dorsal to u-l.labM2 | antero-ventral to esophagus, medial to lg3, ventral to lab-eso.dM2, dorsal to u-l.labM2 |
Connections | esophagus, anterior labrum, u-l.labM2 | esophagus, anterior labrum, u-l.labM 2 | esophagus, anterior labrum, u-l.labM2 | esophagus, anterior labrum, u-l.labM2 | |
Lateral-Esophageal Dilator Muscles 1 (lat-eso.dM1) | Spatial relationships | antero-lateral to esophagus, lateral to for-eso.dM, dorsal to lab-eso.dM1 | antero-lateral to esophagus, lateral to for-eso.dM, dorsal to lab-eso.dM1 | antero-lateral to esophagus, lateral to for-eso.dM, dorsal to lab-eso.dM1 | antero-lateral to esophagus, lateral to for-eso.dM, dorsal to lab-eso.dM1 |
Connections | esophagus, antero-lateral body wall | esophagus, antero-lateral body wall | esophagus, antero-lateral body wall | esophagus, antero-lateral body wall | |
Lateral-Esophageal Dilator Muscles 2 (lat-eso.dM2) | Spatial relationships | lateral to esophagus | lateral to esophagus, dorsal to lg2 | lateral to esophagus | ateral to esophagus, dorsal to lg1 |
Connections | esophagus, antero-lateral body wall | esophagus, antero-lateral body wall | esophagus, antero-lateral body wall | esophagus, antero-lateral body wall | |
Paragnath Muscles (parM) | Spatial relationships | within paragnath | within paragnath | within paragnath | within paragnath, antero-dorsal to lg1C1 |
Connections | anterior paragnath | anterior paragnath | anterior paragnath | anterior paragnath | |
Constituents | 2 pair of muscles | 2 pair of muscles | 2 pair of muscles | 2 pair of muscles | |
Saggital Labral Muscles (s.labM) | Spatial relationships | − | − | − | anterior to posterior wall of labrum, medial to lg1C2, dorsal to lg3C2 |
Connections | − | − | − | dorso-medial of the posterior wall of labrum, ventro-lateral of the posterior wall of labrum | |
Transversus Labral Muscle (t.labM) | Spatial relationships | dorsal to lg3 and lg1, ventral to lab-eso.dM3, between bundles of u-l.labM2 | dorsal to lg3 and lg1, ventral to lab-eso.dM3, between bundles of u-l.labM2 | dorsal to lg3 and lg1, ventral to lab-eso.dM3, between bundles of u-l.labM2 | dorsal to lg3 and lg1, ventral to lab-eso.dM3, between bundles of u-l.labM2 |
Connections | cuticular ridge from dorsal labrum | cuticular ridge from dorsal labrum | cuticular ridge from dorsal labrum | cuticular ridge from dorsal labrum | |
Upper-Lower Labral Muscles 1 (u-l.labM1) | Spatial relationships | medial to u-l.labM2, medial to lab-eso.dM4 | medial to u-l.labM2, medial to lab-eso.dM4, lateral to legC1 | medial to u-l.labM2, medial to lab-eso.dM4 | medial to u-l.labM2, medial to lab-eso.dM4, medial to lg3C2 |
Connections | anterior-medial labrum, ventro-medial of dorsal labrum | anterior-medial labrum, ventro-medial of dorsal labrum | anterior-medial labrum, ventro-medial of dorsal labrum | anterior-medial labrum, ventro-medial of dorsal labrum | |
Upper-Lower Labral Muscles 2 (u-l.labM2) | Spatial relationships | lateral to u-l.labM1, medial to lg3 | lateral to u-l.labM1, medial to lg3 | lateral to u-l.labM1, medial to lg3 | lateral to u-l.labM1, medial to lg3 |
Connections | anterior labrum, posterior labrum | anterior labrum, posterior labrum | anterior labrum, posterior labrum | anterior labrum, posterior labrum | |
GLANDS | |||||
Labral Gland Type 1 (lg1) | Spatial relationships | medial to lb2, lateral to lb3, within labrum | medial to lb2, lateral to lb3, lateral to lab-eso.dM3, within labrum | dorsal to lb, lateral to lb3, lateral to lab-eso.dM3, within labrum | medial to lb2, lateral to lb3, lateral to lab-eso.dM1 and 3, lateral to s.labM, within labrum and paragnath |
Connections | postero-lateral of labrum | postero-lateral of labrum | postero-lateral of labrum | postero-lateral of labrum | |
Constituents | lg1C1-4 | lg1C1 and 2 | lg1C1 and 2 | lg1C1 and 2 | |
Labral Gland Type 2 (lg2) | Spatial relationships | ventro-lateral to lg1 | lateral to lg1 | ventro-lateral to lg1, ventral to lg3, surround lab-eso.dM3 | lateral to lg1, lateral to s.labM |
Connections | postero-ventral edge of labrum | postero-ventral edge of labrum | postero-ventral edge of labrum | postero-ventral edge of labrum | |
Constituents | lg2G1C1-4, lg2G2C1 and 2, lg2G3C1-3 | lg2G1C1 and 2, lg2G2C1 and 2 | lg2G1C1 and 2, lg2G2C1 and 2 | lg2C1-3 | |
Labral Gland Type 3 (lg3) | Spatial relationships | medial to lb1, lateral to u-l.labM2 | medial to lb1, lateral to u-l.labM2 | medial to lb1, lateral to u-l.labM2, medial to lab-eso.dM3 | lateral to u-l.labM2, lateral to lab-eso.dM2 and 4, ventro-lateral to for-eso.dM, medial to lab-eso.dM1 and 3 |
Connections | posterior labrum | posterior labrum | posterior labrum | posterior labrum | |
Constituents | lg3C1 and 2 | lg3C1 and 2 | lg3C1 and 2 | lg3C1-3 | |
Labral Epidermal Glands (leg) | Spatial relationships | − | ventral to u-l.labM1 | ventral to u-l.labM1 | ventral to u-l.labM1, ventral to lg3 |
Connections | − | antero-ventral labrum | antero-ventral labrum | antero-ventral labrum | |
Constituents | − | leg1 and 2 | leg1-8 | leg1-3 | |
Paragnathal Epidermal Glands (peg) | Spatial relationships | − | − | lateral to parM, beside lateral wall of paragnath | lateral to lg1C1, beside lateral wall of paragnath |
Connections | − | − | ventro-lateral paragnath | postero-lateral paragnath | |
Constituents | − | − | peg right 1-3, left 1-3 | pegG1C1 and 2, pegG2C1 and 2 | |