Table 1 Summary of differential morphologies among the four Eubranchipus species

Male, second antenna proximal antennomere apophyses

Chitinized, conical, apically rounded and directed medially

(Fig. 6a and f)

Chitinized, conical, apically rounded and directed medially

(Fig. 9a)

Chitinized, tubular, apically rounded and directed anteriorly

(Fig. 10a)

Less chitinization, conical, apically rounded and directed medially (Fig. 11a)

Male, second antenna distal antennomere medial margin

With a subacute hook projection apically (Fig. 6g)

With an acute hook projection apically (Fig. 9f)

Without a hook projection apically (Fig. 10f)

With an obtuse projection apically (Fig. 11f)

Male, antennal appendage

Tapering from seven tenths of the length, medial margin bearing short digitform papillae continuously (Fig. 6h)

Tapering from medial point, medial margin bearing short digitform papillae sparsely

(Fig. 9g)

Tapering from seven tenths of the length, medial margin bearing short digitform papillae sparsely (Fig. 10g)

Tapering from seven tenths of the length, medial margin bearing short digitform papillae sparsely (Fig. 11g)

Female, brood pouch

Subcylindrical with fat apex

(Fig. 7c and d)

Subspherical with slim apex (Fig. 9e and h)

Subcylindrical with slim apex (Fig. 10e and h)

Subcylindrical with slim apex (Fig. 11e and h)

Female, posterolateral spines of abdomen

On the first, second and third abdominal segments

(Fig. 7d)

On the first, second, third and fourth abdominal segments (Fig. 9e)

On the first and second abdominal segments

(Fig. 10e)

On the first and second abdominal segments

(Fig. 11e)

Female, thoracic dorsolateral lobes

Tenth and eleventh linear lobes, identical in size, projected posteriorly

(Fig. 7b and d)

Tenth and eleventh oval lobes projected posteriorly, tenth lobes the largest

(Fig. 9c and e)

Tenth oval lobes and eleventh lanceolate lobes projected posteriorly, eleventh lobes cover half of the genital segments (Fig. 10c and e)

Tenth and eleventh linear lobes, identical in size, projected posteriorly slightly (Fig. 11c and e)