Introduction: We describe the tagmatization pattern of the anterior region of the extant stomatop... more Introduction: We describe the tagmatization pattern of the anterior region of the extant stomatopod Erugosquilla massavensis. For documentation we used the autofluorescence capacities of the specimens, resulting in a significant contrast between sclerotized and membranous areas. Results: The anterior body region of E. massavensis can be grouped into three tagmata. Tagma I, the sensorial unit, comprises the segments of the eyes, antennules and antennae. This unit is set-off anteriorly from the posterior head region. Ventrally this unit surrounds a large medial sclerite, interpreted as the anterior part of the hypostome. Dorsally the antennular and antennal segments each bear a well-developed tergite. The dorsal shield is part of tagma II, most of the ventral part of which is occupied in the midline by the large, partly sclerotized posterior part of a complex combining hypostome and labrum. Tagma II includes three more segments behind the labrum, the mandibular, maxillulary and maxillary segments. Tagma III includes the maxillipedal segments, bearing five pairs of sub-chelate appendages. The dorsal sclerite of the first of these tagma-III segments, the segment of the first maxillipeds, is not included in the shield, so this segment is not part of tagma II as generally thought. The second and third segments of tagma III form a unit dorsally and ventrally. The tergites of the segments of tagma III become progressively larger from the anterior to the posterior, possibly resulting from a paedomorphic effect during evolution, which caused this reversed enlargement. Conclusions: The described pattern of tagmosis differs from current textbook knowledge. Therefore, our re-description of the anterior body area of stomatopods is of considerable impact for understanding the head evolution of Stomatopoda. Likewise, it has a bearing upon any comparisons with fossil stomatopods, as mainly sclerotized areas are fossilized, and, on a wider scale, upon larger-scale comparisons with other malacostracans and eucrustaceans in general.
The encrustation of the spider crab Hyastenus hilgendorfi inhabiting the Suez Canal in relation t... more The encrustation of the spider crab Hyastenus hilgendorfi inhabiting the Suez Canal in relation to its reproductive biology was studied. This species is considered a by-catch in the area of the Suez Canal. It has a negative impact on fishing gear and causes severe damage. Specimens were collected from July 2009 to June 2010. Crabs were sexed and the degree of encrustation was assessed visually. Females were measured for carapace width and dissected to judge gonad maturation. 1054 specimens were collected, of which 569 (54.0%) were males, 363 (34.4%) non-ovigerous and 122 (11.6%) ovigerous females. 23.7% (250) had no encrustation while 76.3% (804) were covered. 49.5% (398) of encrusted individuals were males; 41.0% (330) were non-ovigerous females and 9.5% (76) were ovigerous females. The degree of encrustation varied with carapace width in ovigerous females. Females outnumbered males by 2.9:1 between December and April. Berried females and those with ripe ovaries existed in all seasons except winter. A single reproductive period from June to November was apparent followed by a resting phase between January and March. The size at which 50% of females were mature was 22.4 mm CW. Fecundity was found to be related to carapace width. It is suspected that this crab may engage in podding behavior. The successful establishment of this species in the Suez Canal may be related to its fecundity, short larval life span and effective camouflage against predatory fishes. Suggestions for the reduction of the impact of the by-catch of this species on the traditional fishery of the Canal are discussed.
We describe the tagmatization pattern of the anterior region of the extant stomatopod Erugosquill... more We describe the tagmatization pattern of the anterior region of the extant stomatopod Erugosquilla massavensis. For documentation we used the autofluorescence capacities of the specimens, resulting in a significant contrast between sclerotized and membranous areas.
Introduction: We describe the tagmatization pattern of the anterior region of the extant stomatop... more Introduction: We describe the tagmatization pattern of the anterior region of the extant stomatopod Erugosquilla massavensis. For documentation we used the autofluorescence capacities of the specimens, resulting in a significant contrast between sclerotized and membranous areas. Results: The anterior body region of E. massavensis can be grouped into three tagmata. Tagma I, the sensorial unit, comprises the segments of the eyes, antennules and antennae. This unit is set-off anteriorly from the posterior head region. Ventrally this unit surrounds a large medial sclerite, interpreted as the anterior part of the hypostome. Dorsally the antennular and antennal segments each bear a well-developed tergite. The dorsal shield is part of tagma II, most of the ventral part of which is occupied in the midline by the large, partly sclerotized posterior part of a complex combining hypostome and labrum. Tagma II includes three more segments behind the labrum, the mandibular, maxillulary and maxillary segments. Tagma III includes the maxillipedal segments, bearing five pairs of sub-chelate appendages. The dorsal sclerite of the first of these tagma-III segments, the segment of the first maxillipeds, is not included in the shield, so this segment is not part of tagma II as generally thought. The second and third segments of tagma III form a unit dorsally and ventrally. The tergites of the segments of tagma III become progressively larger from the anterior to the posterior, possibly resulting from a paedomorphic effect during evolution, which caused this reversed enlargement. Conclusions: The described pattern of tagmosis differs from current textbook knowledge. Therefore, our re-description of the anterior body area of stomatopods is of considerable impact for understanding the head evolution of Stomatopoda. Likewise, it has a bearing upon any comparisons with fossil stomatopods, as mainly sclerotized areas are fossilized, and, on a wider scale, upon larger-scale comparisons with other malacostracans and eucrustaceans in general.
The encrustation of the spider crab Hyastenus hilgendorfi inhabiting the Suez Canal in relation t... more The encrustation of the spider crab Hyastenus hilgendorfi inhabiting the Suez Canal in relation to its reproductive biology was studied. This species is considered a by-catch in the area of the Suez Canal. It has a negative impact on fishing gear and causes severe damage. Specimens were collected from July 2009 to June 2010. Crabs were sexed and the degree of encrustation was assessed visually. Females were measured for carapace width and dissected to judge gonad maturation. 1054 specimens were collected, of which 569 (54.0%) were males, 363 (34.4%) non-ovigerous and 122 (11.6%) ovigerous females. 23.7% (250) had no encrustation while 76.3% (804) were covered. 49.5% (398) of encrusted individuals were males; 41.0% (330) were non-ovigerous females and 9.5% (76) were ovigerous females. The degree of encrustation varied with carapace width in ovigerous females. Females outnumbered males by 2.9:1 between December and April. Berried females and those with ripe ovaries existed in all seasons except winter. A single reproductive period from June to November was apparent followed by a resting phase between January and March. The size at which 50% of females were mature was 22.4 mm CW. Fecundity was found to be related to carapace width. It is suspected that this crab may engage in podding behavior. The successful establishment of this species in the Suez Canal may be related to its fecundity, short larval life span and effective camouflage against predatory fishes. Suggestions for the reduction of the impact of the by-catch of this species on the traditional fishery of the Canal are discussed.
We describe the tagmatization pattern of the anterior region of the extant stomatopod Erugosquill... more We describe the tagmatization pattern of the anterior region of the extant stomatopod Erugosquilla massavensis. For documentation we used the autofluorescence capacities of the specimens, resulting in a significant contrast between sclerotized and membranous areas.
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